diff --git a/ANNOUNCE b/ANNOUNCE
index c0289c1a8..9f1b66583 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.18 - July 23, 2015
+Libpng 1.6.19 - November 12, 2015
 
 This is a public release of libpng, intended for use in production codes.
 
@@ -7,79 +7,104 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.6.18.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.18.tar.gz
+   libpng-1.6.19.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.19.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1618.7z  (LZMA-compressed, recommended)
-   lpng1618.zip
+   lpng1619.7z  (LZMA-compressed, recommended)
+   lpng1619.zip
 
 Other information:
 
-   libpng-1.6.18-README.txt
-   libpng-1.6.18-LICENSE.txt
-   libpng-1.6.18-*.asc (armored detached GPG signatures)
+   libpng-1.6.19-README.txt
+   libpng-1.6.19-LICENSE.txt
+   libpng-1.6.19-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.6.17):
-  Removed PNG_SET_CHUNK_[CACHE|MALLOC]_LIMIT_SUPPORTED macros.  They
-    have been combined with PNG_SET_USER_LIMITS_SUPPORTED (resolves
-    bug report by Andrew Church).
-  Fixed rgb_to_gray checks and added tRNS checks to pngvalid.c.  This
-    fixes some arithmetic errors that caused some tests to fail on
-    some 32-bit platforms (Bug reports by Peter Breitenlohner [i686]
-    and Petr Gajdos [i586]).
+Changes since the last public release (1.6.18):
+
+  Updated obsolete information about the simplified API macros in the
+    manual pages (Bug report by Arc Riley).
+  Avoid potentially dereferencing NULL info_ptr in png_info_init_3().
+  Rearranged png.h to put the major sections in the same order as
+    in libpng17.
+  Eliminated unused PNG_COST_SHIFT, PNG_WEIGHT_SHIFT, PNG_COST_FACTOR, and
+    PNG_WEIGHT_FACTOR macros.
   Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
-    (Bug report by Viktor Szaka'ts).
-  Replaced "unexpected" with an integer (0xabadca11) in pngset.c
-    where a long was expected, to avoid a compiler warning when PNG_DEBUG > 1.
-  Added contrib/examples/simpleover.c, to demonstrate how to handle
-    alpha compositing of multiple images, using the "simplified API"
-    and an example PNG generation tool, contrib/examples/genpng.c
+    (Bug report by Viktor Szakats).  Several warnings remain and are
+    unavoidable, where we test for overflow.
+  Fixed potential leak of png_pixels in contrib/pngminus/pnm2png.c
+  Fixed uninitialized variable in contrib/gregbook/rpng2-x.c
+  Moved config.h.in~ from the "libpng_autotools_files" list to the
+    "libpng_autotools_extra" list in autogen.sh because it was causing a
+    false positive for missing files (bug report by Robert C. Seacord).
+  Removed unreachable "break" statements in png.c, pngread.c, and pngrtran.c
+    to suppress clang warnings (Bug report by Viktor Szakats).
+  Fixed some bad links in the man page.
+  Changed "n bit" to "n-bit" in comments.
+  Added signed/unsigned 16-bit safety net. This removes the dubious
+    0x8000 flag definitions on 16-bit systems. They aren't supported
+    yet the defs *probably* work, however it seems much safer to do this
+    and be advised if anyone, contrary to advice, is building libpng 1.6
+    on a 16-bit system. It also adds back various switch default clauses
+    for GCC; GCC errors out if they are not present (with an appropriately
+    high level of warnings).
+  Safely convert num_bytes to a png_byte in png_set_sig_bytes() (Robert
+    Seacord).
+  Fixed the recently reported 1's complement security issue by replacing
+    the value that is illegal in the PNG spec, in both signed and unsigned
+    values, with 0. Illegal unsigned values (anything greater than or equal
+    to  0x80000000) can still pass through, but since these are not illegal
+    in ANSI-C (unlike 0x80000000 in the signed case) the checking that
+    occurs later can catch them (John Bowler).
+  Fixed png_save_int_32 when int is not 2's complement (John Bowler).
+  Updated libpng16 with all the recent test changes from libpng17,
+    including changes to pngvalid.c to ensure that the original,
+    distributed, version of contrib/visupng/cexcept.h can be used
     (John Bowler).
-  PNG_RELEASE_BUILD replaces tests where the code depended on the build base
-    type and can be defined on the command line, allowing testing in beta
-    builds (John Bowler).
-  Avoid Coverity issue 80858 (REVERSE NULL) in pngtest.c
-  Avoid a harmless potential integer overflow in png_XYZ_from_xy() (Bug
-    report from Christopher Ferris).
-  Backport filter selection code from libpng-1.7.0beta51, to combine
-    sub_row, up_row, avg_row, and paeth_row into try_row and tst_row.
-  Changed png_voidcast(), etc., to voidcast(), etc., in contrib/tools/pngfix.c
-    to avoid confusion with the libpng private macros.
-  Fixed old cut&paste bug in the weighted filter selection code in
-    pngwutil.c, introduced in libpng-0.95, March 1997.
-  Removed WRITE_WEIGHTED_FILTERED code, to save a few kbytes of the
-    compiled library size. It never worked properly and as far as we can
-    tell, no one uses it. The png_set_filter_heuristics() and
-    png_set_filter_heuristics_fixed() APIs are retained but deprecated
-    and do nothing.
-  Quieted some Coverity issues in pngfix.c, png-fix-itxt.c, pngvalid.c,
-    pngstest.c, and pngimage.c. Most seem harmless, but png-fix-itxt
-    would only work with iTXt chunks with length 255 or less.
-  Removed non-working progressive reader 'skip' function. This
-    function has apparently never been used. It was implemented
-    to support back-door modification of png_struct in libpng-1.4.x
-    but (because it does nothing and cannot do anything) was apparently
-    never tested (John Bowler).
-  Fixed cexcept.h in which GCC 5 now reports that one of the auto
-    variables in the Try macro needs to be volatile to prevent value
-    being lost over the setjmp (John Bowler).
-  Added #ifdef's to contrib/examples programs so people don't try
-    to compile them without the minimum required support enabled
-    (suggested by Flavio Medeiros).
-  Eliminated the final two Coverity defects (insecure temporary file
-    handling in contrib/libtests/pngstest.c; possible overflow of
-    unsigned char in contrib/tools/png-fix-itxt.c). To use the "secure"
-    file handling, define PNG_USE_MKSTEMP, otherwise "tmpfile()" will
-    be used.
-  Removed some unused WEIGHTED_FILTER macros from pngstruct.h
-  Replaced arbitrary use of 'extern' with #define PNG_LINKAGE_*.  To
-    preserve API compatibility, the new defines all default to "extern"
-    (requested by Jan Nijtmans).
-  Belatedly added Mans Rullgard and James Yu to the list of Contributing
-    Authors.
+  pngvalid contains the correction to the use of SAVE/STORE_
+    UNKNOWN_CHUNKS; a bug revealed by changes in libpng 1.7. More
+    tests contain the --strict option to detect warnings and the
+    pngvalid-standard test has been corrected so that it does not
+    turn on progressive-read. There is a separate test which does
+    that. (John Bowler)
+  Also made some signed/unsigned fixes.
+  Make pngstest error limits version specific. Splitting the machine
+    generated error structs out to a file allows the values to be updated
+    without changing pngstest.c itself. Since libpng 1.6 and 1.7 have
+    slightly different error limits this simplifies maintenance. The
+    makepngs.sh script has also been updated to more accurately reflect
+    current problems in libpng 1.7 (John Bowler).
+  Incorporated new test PNG files into make check.  tests/pngstest-*
+    are changed so that the new test files are divided into 8 groups by
+    gamma and alpha channel.  These tests have considerably better code
+    and pixel-value coverage than contrib/pngsuite; however,coverage is
+    still incomplete (John Bowler).
+  Removed the '--strict' in 1.6 because of the double-gamma-correction
+    warning, updated pngstest-errors.h for the errors detected with the
+    new contrib/testspngs PNG test files (John Bowler).
+  Worked around rgb-to-gray issues in libpng 1.6.  The previous
+    attempts to ignore the errors in the code aren't quite enough to
+    deal with the 'channel selection' encoding added to libpng 1.7; abort.
+  Fixed 'pow' macros in pngvalid.c. It is legal for 'pow' to be a
+    macro, therefore the argument list cannot contain preprocessing
+    directives.  Make sure pow is a function where this happens. This is
+    a minimal safe fix, the issue only arises in non-performance-critical
+    code (bug report by Curtis Leach, fix by John Bowler).
+  Added sPLT support to pngtest.c
+  Prevent setting or writing over-length PLTE chunk (Cosmin Truta).
+  Silently truncate over-length PLTE chunk while reading.
+  Libpng incorrectly calculated the output rowbytes when the application
+    decreased either the number of channels or the bit depth (or both) in
+    a user transform.  This was safe; libpng overallocated buffer space
+   (potentially by quite a lot; up to 4 times the amount required) but,
+   from 1.5.4 on, resulted in a png_error (John Bowler).
+  Fixed some inconsequential cut-and-paste typos in png_set_cHRM_XYZ_fixed().
+  Clarified COPYRIGHT information to state explicitly that versions
+    are derived from previous versions.
+  Removed much of the long list of previous versions from png.h and
+    libpng.3.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index d678392a5..2e4d2bb29 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3756,8 +3756,9 @@ Version 1.5.7beta04 [November 17, 2011]
 
 Version 1.5.7beta05 [November 25, 2011]
   Removed "zTXt" from warning in generic chunk decompression function.
-  Validate time settings passed to pngset() and png_convert_to_rfc1123()
-    (Frank Busse).
+  Validate time settings passed to png_set_tIME() and png_convert_to_rfc1123()
+    (Frank Busse). Note: This prevented CVE-2015-7981 from affecting
+    libpng-1.5.7 and later.
   Added MINGW support to CMakeLists.txt
   Reject invalid compression flag or method when reading the iTXt chunk.
   Backed out 'simplified' API changes. The API seems too complex and there
@@ -3803,12 +3804,13 @@ Version 1.6.0beta01 [December 15, 2011]
     (the other two required headers aren't used).  Non-ANSI systems that don't
     have stddef.h or limits.h will have to provide an appropriate fake
     containing the relevant types and #defines.
-  The use of FAR/far has been eliminated and the definition of png_alloc_size_t
-    is now controlled by a flag so that 'small size_t' systems can select it
-    if necessary.  Libpng 1.6 may not currently work on such systems -- it
-    seems likely that it will ask 'malloc' for more than 65535 bytes with any
-    image that has a sufficiently large row size (rather than simply failing
-    to read such images).
+  Dropped support for 16-bit platforms. The use of FAR/far has been eliminated
+    and the definition of png_alloc_size_t is now controlled by a flag so
+    that 'small size_t' systems can select it if necessary.  Libpng 1.6 may
+    not currently work on such systems -- it seems likely that it will
+    ask 'malloc' for more than 65535 bytes with any image that has a
+    sufficiently large row size (rather than simply failing to read such
+    images).
   New tools directory containing tools used to generate libpng code.
   Fixed race conditions in parallel make builds. With higher degrees of
     parallelism during 'make' the use of the same temporary file names such
@@ -4420,7 +4422,7 @@ Version 1.6.1beta02 [February 19, 2013]
 
 Version 1.6.1beta03 [February 22, 2013]
   Fixed ALIGNED_MEMORY support.
-  Allow run-time ARM NEON checking to be disabled. A new configure option:
+  Added a new configure option:
     --enable-arm-neon=always will stop the run-time checks. New checks
     within arm/arm_init.c will cause the code not to be compiled unless
     __ARM_NEON__ is set. This should make it fail safe (if someone asks
@@ -4439,10 +4441,10 @@ Version 1.6.1beta05 [March 1, 2013]
 Version 1.6.1beta06 [March 4, 2013]
   Better documentation of unknown handling API interactions.
   Corrected Android builds and corrected libpng.vers with symbol
-    prefixing. This adds an API to set optimization options externally,
+    prefixing.  It also makes those tests compile and link on Android.
+  Added an API png_set_option() to set optimization options externally,
     providing an alternative and general solution for the non-portable
-    run-time tests used by the ARM Neon code.  It also makes those tests
-    compile and link on Android.
+    run-time tests used by the ARM Neon code, using the PNG_ARM_NEON option.
   The order of settings vs options in pnglibconf.h is reversed to allow
     settings to depend on options and options can now set (or override) the
     defaults for settings.
@@ -4540,7 +4542,8 @@ Version 1.6.3beta05 [May 9, 2013]
   Calculate our own zlib windowBits when decoding rather than trusting the
     CMF bytes in the PNG datastream.
   Added an option to force maximum window size for inflating, which was
-    the behavior of libpng15 and earlier.
+    the behavior of libpng15 and earlier, via a new PNG_MAXIMUM_INFLATE_WINDOW
+    option for png_set_options().
   Added png-fix-itxt and png-fix-too-far-back to the built programs and
     removed warnings from the source code and timepng that are revealed as
     a result.
@@ -5143,7 +5146,9 @@ Version 1.6.17beta01 [January 29, 2015]
   Added testing of png_set_packing() to pngvalid.c
   Regenerated configure scripts in the *.tar distributions with libtool-2.4.4
   Implement previously untested cases of libpng transforms in pngvalid.c
-  Fixed byte order in 2-byte filler, in png_do_read_filler().
+  Fixed byte order in png_do_read_filler() with 16-bit input. Previously
+    the high and low bytes of the filler, from png_set_filler() or from
+    png_set_add_alpha(), were read in the wrong order.
   Made the check for out-of-range values in png_set_tRNS() detect
     values that are exactly 2^bit_depth, and work on 16-bit platforms.
   Merged some parts of libpng-1.6.17beta01 and libpng-1.7.0beta47.
@@ -5225,7 +5230,7 @@ Version 1.6.18beta01 [April 1, 2015]
 
 Version 1.6.18beta02 [April 26, 2015]
   Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
-    (Bug report by Viktor Szaka'ts).
+    (Bug report by Viktor Szakats).
 
 Version 1.6.18beta03 [May 6, 2015]
   Replaced "unexpected" with an integer (0xabadca11) in pngset.c
@@ -5305,6 +5310,110 @@ Version 1.6.18rc03 [July 15, 2015]
 Version 1.6.18 [July 23, 2015]
   No changes.
 
+Version 1.6.19beta01 [July 30, 2015]
+  Updated obsolete information about the simplified API macros in the
+    manual pages (Bug report by Arc Riley).
+  Avoid potentially dereferencing NULL info_ptr in png_info_init_3().
+  Rearranged png.h to put the major sections in the same order as
+    in libpng17.
+  Eliminated unused PNG_COST_SHIFT, PNG_WEIGHT_SHIFT, PNG_COST_FACTOR, and
+    PNG_WEIGHT_FACTOR macros.
+  Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
+    (Bug report by Viktor Szakats).  Several warnings remain and are
+    unavoidable, where we test for overflow.
+  Fixed potential leak of png_pixels in contrib/pngminus/pnm2png.c
+  Fixed uninitialized variable in contrib/gregbook/rpng2-x.c
+
+Version 1.6.19beta02 [August 19, 2015]
+  Moved config.h.in~ from the "libpng_autotools_files" list to the
+    "libpng_autotools_extra" list in autogen.sh because it was causing a
+    false positive for missing files (bug report by Robert C. Seacord).
+  Removed unreachable "break" statements in png.c, pngread.c, and pngrtran.c
+    to suppress clang warnings (Bug report by Viktor Szakats).
+  Fixed some bad links in the man page.
+  Changed "n bit" to "n-bit" in comments.
+  Added signed/unsigned 16-bit safety net. This removes the dubious
+    0x8000 flag definitions on 16-bit systems. They aren't supported
+    yet the defs *probably* work, however it seems much safer to do this
+    and be advised if anyone, contrary to advice, is building libpng 1.6
+    on a 16-bit system. It also adds back various switch default clauses
+    for GCC; GCC errors out if they are not present (with an appropriately
+    high level of warnings).
+  Safely convert num_bytes to a png_byte in png_set_sig_bytes() (Robert
+    Seacord).
+  Fixed the recently reported 1's complement security issue by replacing
+    the value that is illegal in the PNG spec, in both signed and unsigned
+    values, with 0. Illegal unsigned values (anything greater than or equal
+    to  0x80000000) can still pass through, but since these are not illegal
+    in ANSI-C (unlike 0x80000000 in the signed case) the checking that
+    occurs later can catch them (John Bowler).
+
+Version 1.6.19beta03 [September 26, 2015]
+  Fixed png_save_int_32 when int is not 2's complement (John Bowler).
+  Updated libpng16 with all the recent test changes from libpng17,
+    including changes to pngvalid.c to ensure that the original,
+    distributed, version of contrib/visupng/cexcept.h can be used
+    (John Bowler).
+  pngvalid contains the correction to the use of SAVE/STORE_
+    UNKNOWN_CHUNKS; a bug revealed by changes in libpng 1.7. More
+    tests contain the --strict option to detect warnings and the
+    pngvalid-standard test has been corrected so that it does not
+    turn on progressive-read. There is a separate test which does
+    that. (John Bowler)
+  Also made some signed/unsigned fixes.
+  Make pngstest error limits version specific. Splitting the machine
+    generated error structs out to a file allows the values to be updated
+    without changing pngstest.c itself. Since libpng 1.6 and 1.7 have
+    slightly different error limits this simplifies maintenance. The
+    makepngs.sh script has also been updated to more accurately reflect
+    current problems in libpng 1.7 (John Bowler).
+  Incorporated new test PNG files into make check.  tests/pngstest-*
+    are changed so that the new test files are divided into 8 groups by
+    gamma and alpha channel.  These tests have considerably better code
+    and pixel-value coverage than contrib/pngsuite; however,coverage is
+    still incomplete (John Bowler).
+  Removed the '--strict' in 1.6 because of the double-gamma-correction
+    warning, updated pngstest-errors.h for the errors detected with the
+    new contrib/testspngs PNG test files (John Bowler).
+
+Version 1.6.19beta04 [October 15, 2015]
+  Worked around rgb-to-gray issues in libpng 1.6.  The previous
+    attempts to ignore the errors in the code aren't quite enough to
+    deal with the 'channel selection' encoding added to libpng 1.7; abort.
+    pngvalid.c is changed to drop this encoding in prior versions.
+  Fixed 'pow' macros in pngvalid.c. It is legal for 'pow' to be a
+    macro, therefore the argument list cannot contain preprocessing
+    directives.  Make sure pow is a function where this happens. This is
+    a minimal safe fix, the issue only arises in non-performance-critical
+    code (bug report by Curtis Leach, fix by John Bowler).
+  Added sPLT support to pngtest.c
+
+Version 1.6.19rc01 [October 23, 2015]
+  No changes.
+
+Version 1.6.19rc02 [October 31, 2015]
+  Prevent setting or writing over-length PLTE chunk (Cosmin Truta).
+  Silently truncate over-length PLTE chunk while reading.
+  Libpng incorrectly calculated the output rowbytes when the application
+    decreased either the number of channels or the bit depth (or both) in
+    a user transform.  This was safe; libpng overallocated buffer space
+   (potentially by quite a lot; up to 4 times the amount required) but,
+   from 1.5.4 on, resulted in a png_error (John Bowler).
+
+Version 1.6.19rc03 [November 3, 2015]
+  Fixed some inconsequential cut-and-paste typos in png_set_cHRM_XYZ_fixed().
+  Clarified COPYRIGHT information to state explicitly that versions
+    are derived from previous versions.
+  Removed much of the long list of previous versions from png.h and
+    libpng.3.
+
+Version 1.6.19rc04 [November 5, 2015]
+  Fixed new bug with CRC error after reading an over-length palette
+    (bug report by Cosmin Truta).
+
+Version 1.6.19 [November 12, 2015]
+  Cleaned up coding style in png_handle_PLTE().
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 62d516070..411f8753c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,7 +16,7 @@ enable_testing()
 
 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 18)
+set(PNGLIB_RELEASE 19)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
 
@@ -261,7 +261,7 @@ endif(NOT WIN32 OR CYGWIN OR MINGW)
 # SET UP LINKS
 if(PNG_SHARED)
   set_target_properties(${PNG_LIB_NAME} PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.18
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.19
     VERSION 16.${PNGLIB_RELEASE}.0
     SOVERSION 16
     CLEAN_DIRECT_OUTPUT 1)
diff --git a/LICENSE b/LICENSE
index 090a3600c..11f6ffe5d 100644
--- a/LICENSE
+++ b/LICENSE
@@ -10,10 +10,11 @@ this sentence.
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000, through 1.6.18, July 23, 2015, are
-Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, and are
-distributed according to the same disclaimer and license as libpng-1.0.6
-with the following individuals added to the list of Contributing Authors:
+libpng versions 1.0.7, July 1, 2000, through 1.6.19, November 12, 2015, are
+Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+derived from libpng-1.0.6, and are distributed according to the same
+disclaimer and license as libpng-1.0.6 with the following individuals
+added to the list of Contributing Authors:
 
    Simon-Pierre Cadieux
    Eric S. Raymond
@@ -32,18 +33,20 @@ and with the following additions to the disclaimer:
    the user.
 
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
-Copyright (c) 1998-2000 Glenn Randers-Pehrson, and are distributed according
-to the same disclaimer and license as libpng-0.96, with the following
-individuals added to the list of Contributing Authors:
+Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+libpng-0.96, and are distributed according to the same disclaimer and
+license as libpng-0.96, with the following individuals added to the list
+of Contributing Authors:
 
    Tom Lane
    Glenn Randers-Pehrson
    Willem van Schaik
 
 libpng versions 0.89, June 1996, through 0.96, May 1997, are
-Copyright (c) 1996-1997 Andreas Dilger, and are
-distributed according to the same disclaimer and license as libpng-0.88,
-with the following individuals added to the list of Contributing Authors:
+Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+and are distributed according to the same disclaimer and license as
+libpng-0.88, with the following individuals added to the list of
+Contributing Authors:
 
    John Bowler
    Kevin Bracey
@@ -90,6 +93,8 @@ supporting the PNG file format in commercial products.  If you use this
 source code in a product, acknowledgment is not required but would be
 appreciated.
 
+END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
+
 A "png_get_copyright" function is available, for convenient use in "about"
 boxes and the like:
 
@@ -104,4 +109,4 @@ the additional disclaimers inserted at version 1.0.7.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-July 23, 2015
+November 12, 2015
diff --git a/Makefile.am b/Makefile.am
index ac5f95cf7..73097dbcc 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -51,23 +51,17 @@ TESTS =\
    tests/pngvalid-gamma-expand16-background\
    tests/pngvalid-gamma-expand16-transform tests/pngvalid-gamma-sbit\
    tests/pngvalid-gamma-threshold tests/pngvalid-gamma-transform\
-   tests/pngvalid-progressive-interlace-size\
+   tests/pngvalid-progressive-size\
    tests/pngvalid-progressive-interlace-standard\
-   tests/pngvalid-progressive-interlace-transform\
+   tests/pngvalid-transform\
    tests/pngvalid-progressive-standard tests/pngvalid-standard\
-   tests/pngstest-0g01 tests/pngstest-0g02 tests/pngstest-0g04\
-   tests/pngstest-0g08 tests/pngstest-0g16 tests/pngstest-2c08\
-   tests/pngstest-2c16 tests/pngstest-3p01 tests/pngstest-3p02\
-   tests/pngstest-3p04 tests/pngstest-3p08 tests/pngstest-4a08\
-   tests/pngstest-4a16 tests/pngstest-6a08 tests/pngstest-6a16\
-   tests/pngstest-error tests/pngunknown-IDAT\
+   tests/pngstest-1.8 tests/pngstest-1.8-alpha tests/pngstest-linear\
+   tests/pngstest-linear-alpha tests/pngstest-none tests/pngstest-none-alpha\
+   tests/pngstest-sRGB tests/pngstest-sRGB-alpha tests/pngunknown-IDAT\
    tests/pngunknown-discard tests/pngunknown-if-safe tests/pngunknown-sAPI\
    tests/pngunknown-sTER tests/pngunknown-save tests/pngunknown-vpAg\
    tests/pngimage-quick tests/pngimage-full
 
-# These tests are expected, and required, to fail:
-XFAIL_TESTS = tests/pngstest-error
-
 # man pages
 dist_man_MANS= libpng.3 libpngpf.3 png.5
 
diff --git a/README b/README
index 3c181a304..17484e0fd 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-README for libpng version 1.6.18 - July 23, 2015 (shared library 16.0)
+README for libpng version 1.6.19 - November 12, 2015 (shared library 16.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
diff --git a/autogen.sh b/autogen.sh
index 702a0c110..91607171b 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -74,12 +74,12 @@ done
 #
 # The autotools generated files:
 libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
-   config.h.in~ config.sub configure depcomp install-sh ltmain.sh missing\
+   config.sub configure depcomp install-sh ltmain.sh missing\
    test-driver"
 #
 # Files generated by versions of configue >2.68 or automake >1.13 (i.e. later
 # versions than those required by configure.ac):
-libpng_autotools_extra="compile"
+libpng_autotools_extra="compile config.h.in~"
 #
 # These are separate because 'maintainer-clean' does not remove them.
 libpng_libtool_files="scripts/libtool.m4 scripts/ltoptions.m4\
diff --git a/configure.ac b/configure.ac
index 4fb07785f..c1e404ab8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,7 +18,7 @@ AC_PREREQ([2.68])
 
 dnl Version number stuff here:
 
-AC_INIT([libpng],[1.6.18],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.19],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])
 
 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -39,10 +39,10 @@ dnl automake, so the following is not necessary (and is not defined anyway):
 dnl AM_PREREQ([1.11.2])
 dnl stop configure from automagically running automake
 
-PNGLIB_VERSION=1.6.18
+PNGLIB_VERSION=1.6.19
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=18
+PNGLIB_RELEASE=19
 
 dnl End of version number stuff
 
diff --git a/contrib/README.txt b/contrib/README.txt
index bcd433d35..97963c6d5 100644
--- a/contrib/README.txt
+++ b/contrib/README.txt
@@ -1,4 +1,5 @@
 
 This "contrib" directory contains contributions which are not necessarily under
 the libpng license, although all are open source.  They are not part of
-libpng proper and are not used for building the library.
+libpng proper and are not used for building the library, although some are used
+for testing the library via "make check".
diff --git a/contrib/examples/pngpixel.c b/contrib/examples/pngpixel.c
index 27f2cb936..f762379ed 100644
--- a/contrib/examples/pngpixel.c
+++ b/contrib/examples/pngpixel.c
@@ -87,7 +87,7 @@ print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
        */
       case PNG_COLOR_TYPE_PALETTE:
          {
-            PNG_CONST unsigned int index = component(row, x, 0, bit_depth, 1);
+            PNG_CONST int index = component(row, x, 0, bit_depth, 1);
             png_colorp palette = NULL;
             int num_palette = 0;
 
diff --git a/contrib/gregbook/readpng2.c b/contrib/gregbook/readpng2.c
index 4cf2600a4..a9e7ba59d 100644
--- a/contrib/gregbook/readpng2.c
+++ b/contrib/gregbook/readpng2.c
@@ -4,7 +4,7 @@
 
   ---------------------------------------------------------------------------
 
-      Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2015 Greg Roelofs.  All rights reserved.
 
       This software is provided "as is," without warranty of any kind,
       express or implied.  In no event shall the author or contributors
@@ -51,6 +51,11 @@
       along with this program; if not, write to the Free Software Foundation,
       Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
+  ---------------------------------------------------------------------------
+
+   Changelog:
+     %RDATE% - Check return value of png_get_bKGD() (Glenn R-P)
+
   ---------------------------------------------------------------------------*/
 
 
@@ -261,36 +266,38 @@ static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr)
     /* since we know we've read all of the PNG file's "header" (i.e., up
      * to IDAT), we can check for a background color here */
 
-    if (mainprog_ptr->need_bgcolor &&
-        png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD))
+    if (mainprog_ptr->need_bgcolor)
     {
         png_color_16p pBackground;
 
         /* it is not obvious from the libpng documentation, but this function
          * takes a pointer to a pointer, and it always returns valid red,
          * green and blue values, regardless of color_type: */
-        png_get_bKGD(png_ptr, info_ptr, &pBackground);
+        if (png_get_bKGD(png_ptr, info_ptr, &pBackground))
+        {
 
-        /* however, it always returns the raw bKGD data, regardless of any
-         * bit-depth transformations, so check depth and adjust if necessary */
-        if (bit_depth == 16) {
-            mainprog_ptr->bg_red   = pBackground->red   >> 8;
-            mainprog_ptr->bg_green = pBackground->green >> 8;
-            mainprog_ptr->bg_blue  = pBackground->blue  >> 8;
-        } else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
-            if (bit_depth == 1)
-                mainprog_ptr->bg_red = mainprog_ptr->bg_green =
-                  mainprog_ptr->bg_blue = pBackground->gray? 255 : 0;
-            else if (bit_depth == 2)
-                mainprog_ptr->bg_red = mainprog_ptr->bg_green =
-                  mainprog_ptr->bg_blue = (255/3) * pBackground->gray;
-            else /* bit_depth == 4 */
-                mainprog_ptr->bg_red = mainprog_ptr->bg_green =
-                  mainprog_ptr->bg_blue = (255/15) * pBackground->gray;
-        } else {
-            mainprog_ptr->bg_red   = (uch)pBackground->red;
-            mainprog_ptr->bg_green = (uch)pBackground->green;
-            mainprog_ptr->bg_blue  = (uch)pBackground->blue;
+           /* however, it always returns the raw bKGD data, regardless of any
+            * bit-depth transformations, so check depth and adjust if necessary
+            */
+           if (bit_depth == 16) {
+               mainprog_ptr->bg_red   = pBackground->red   >> 8;
+               mainprog_ptr->bg_green = pBackground->green >> 8;
+               mainprog_ptr->bg_blue  = pBackground->blue  >> 8;
+           } else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
+               if (bit_depth == 1)
+                   mainprog_ptr->bg_red = mainprog_ptr->bg_green =
+                     mainprog_ptr->bg_blue = pBackground->gray? 255 : 0;
+               else if (bit_depth == 2)
+                   mainprog_ptr->bg_red = mainprog_ptr->bg_green =
+                     mainprog_ptr->bg_blue = (255/3) * pBackground->gray;
+               else /* bit_depth == 4 */
+                   mainprog_ptr->bg_red = mainprog_ptr->bg_green =
+                     mainprog_ptr->bg_blue = (255/15) * pBackground->gray;
+           } else {
+               mainprog_ptr->bg_red   = (uch)pBackground->red;
+               mainprog_ptr->bg_green = (uch)pBackground->green;
+               mainprog_ptr->bg_blue  = (uch)pBackground->blue;
+           }
         }
     }
 
diff --git a/contrib/gregbook/rpng2-x.c b/contrib/gregbook/rpng2-x.c
index cf371014c..eea95fbd4 100644
--- a/contrib/gregbook/rpng2-x.c
+++ b/contrib/gregbook/rpng2-x.c
@@ -43,12 +43,10 @@
     - 2.03:  deleted runtime MMX-enabling/disabling and obsolete -mmx* options
     - 2.04:  Added "void(foo);" statements to quiet pedantic compiler warnings
              about unused variables (GR-P)
-
-  TO DO:
-             use nanosleep() instead of usleep(), which is obsolete/deprecated.
+    - 2.05:  Use nanosleep() instead of usleep(), which is deprecated (GR-P).
   ---------------------------------------------------------------------------
 
-      Copyright (c) 1998-2008 Greg Roelofs.  All rights reserved.
+      Copyright (c) 1998-2010, 2014-2015 Greg Roelofs.  All rights reserved.
 
       This software is provided "as is," without warranty of any kind,
       express or implied.  In no event shall the author or contributors
@@ -119,6 +117,7 @@
 # undef usleep
 # define usleep(usec) {        \
    struct timespec ts;         \
+   ts.tv_sec = 0;              \
    ts.tv_nsec = (usec) * 1000; \
    nanosleep(&ts, NULL); }
 #  endif
diff --git a/contrib/libtests/fakepng.c b/contrib/libtests/fakepng.c
index fcc111286..6512c1401 100644
--- a/contrib/libtests/fakepng.c
+++ b/contrib/libtests/fakepng.c
@@ -1,4 +1,12 @@
-/* Fake a PNG - just write it out directly. */
+/* Fake a PNG - just write it out directly.
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2014.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work.  This work is published from:
+ * United States.
+ *
+ */
+
 #include <stdio.h>
 #include <zlib.h> /* for crc32 */
 
diff --git a/contrib/libtests/makepng.c b/contrib/libtests/makepng.c
index 9f11b2964..d4b850485 100644
--- a/contrib/libtests/makepng.c
+++ b/contrib/libtests/makepng.c
@@ -1,8 +1,9 @@
-/* makepng.c
- *
- * Copyright (c) 2013 John Cunningham Bowler
- *
- * Last changed in libpng 1.6.1 [March 28, 2013]
+/* makepng.c */
+#define _ISOC99_SOURCE
+/* Copyright: */
+#define COPYRIGHT "\251 2013,2015 John Cunningham Bowler"
+/*
+ * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -10,8 +11,8 @@
  *
  * Make a test PNG image.  The arguments are as follows:
  *
- *  makepng [--sRGB|--linear|--1.8] [--color=<color>] color-type bit-depth \
- *      [file-name]
+ *    makepng [--sRGB|--linear|--1.8] [--tRNS] [--nofilters] \
+ *       color-type bit-depth [file-name]
  *
  * The color-type may be numeric (and must match the numbers used by the PNG
  * specification) or one of the format names listed below.  The bit-depth is the
@@ -39,8 +40,8 @@
  * 4 channels: linear combinations of, from the top-left corner clockwise,
  *    transparent, red, green, blue.
  *
- * For color-mapped images a four channel color-map is used and the PNG file has
- * a tRNS chunk, as follows:
+ * For color-mapped images a four channel color-map is used and if --tRNS is
+ * given the PNG file has a tRNS chunk, as follows:
  *
  * 1-bit: entry 0 is transparent-red, entry 1 is opaque-white
  * 2-bit: entry 0: transparent-green
@@ -53,6 +54,9 @@
  * The palette always has 2^bit-depth entries and the tRNS chunk one fewer.  The
  * image is the 1-channel diamond, but using palette index, not luminosity.
  *
+ * For formats other than color-mapped ones if --tRNS is specified a tRNS chunk
+ * is generated with all channels equal to the low bits of 0x0101.
+ *
  * Image size is determined by the final pixel depth in bits, i.e. channels x
  * bit-depth, as follows:
  *
@@ -60,20 +64,64 @@
  * 16 bits:           256x256
  * More than 16 bits: 1024x1024
  *
- * Row filtering is turned off (the 'none' filter is used on every row) and the
- * images are not interlaced.
+ * Row filtering is the libpng default but may be turned off (the 'none' filter
+ * is used on every row) with the --nofilters option.
+ *
+ * The images are not interlaced.
+ *
+ * If file-name is given then the PNG is written to that file, else it is
+ * written to stdout.  Notice that stdout is not supported on systems where, by
+ * default, it assumes text output; this program makes no attempt to change the
+ * text mode of stdout!
+ *
+ *    makepng --color=<color> ...
  *
  * If --color is given then the whole image has that color, color-mapped images
  * will have exactly one palette entry and all image files with be 16x16 in
  * size.  The color value is 1 to 4 decimal numbers as appropriate for the color
  * type.
  *
- * If file-name is given then the PNG is written to that file, else it is
- * written to stdout.  Notice that stdout is not supported on systems where, by
- * default, it assumes text output; this program makes no attempt to change the
- * text mode of stdout!
+ *    makepng --small ...
+ *
+ * If --small is given the images are no larger than required to include every
+ * possible pixel value for the format.
+ *
+ * For formats with pixels 8 bits or fewer in size the images consist of a
+ * single row with 2^pixel-depth pixels, one of every possible value.
+ *
+ * For formats with 16-bit pixels a 256x256 image is generated containing every
+ * possible pixel value.
+ *
+ * For larger pixel sizes a 256x256 image is generated where the first row
+ * consists of each pixel that has identical byte values throughout the pixel
+ * followed by rows where the byte values differ within the pixel.
+ *
+ * In all cases the pixel values are arranged in such a way that the SUB and UP
+ * filters give byte sequences for maximal zlib compression.  By default (if
+ * --nofilters is not given) the SUB filter is used on the first row and the UP
+ * filter on all following rows.
+ *
+ * The --small option is meant to provide good test-case coverage, however the
+ * images are not easy to examine visually.  Without the --small option the
+ * images contain identical color values; the pixel values are adjusted
+ * according to the gamma encoding with no gamma encoding being interpreted as
+ * sRGB.
+ *
+ * LICENSING
+ * =========
+ *
+ * This code is copyright of the authors, see the COPYRIGHT define above.  The
+ * code is licensed as above, using the libpng license.  The code generates
+ * images which are solely the product of the code; the options choose which of
+ * the many possibilities to generate.  The images that result (but not the code
+ * which generates them) are licensed as defined here:
+ *
+ * IMPORTANT: the COPYRIGHT #define must contain ISO-Latin-1 characters, the
+ * IMAGE_LICENSING #define must contain UTF-8 characters.  The 'copyright'
+ * symbol 0xA9U (\251) in ISO-Latin-1 encoding and 0xC20xA9 (\302\251) in UTF-8.
  */
-#define _ISOC99_SOURCE /* for strtoull */
+#define IMAGE_LICENSING "Dedicated to the public domain per Creative Commons "\
+    "license \"CC0 1.0\"; https://creativecommons.org/publicdomain/zero/1.0/"
 
 #include <stddef.h> /* for offsetof */
 #include <stdlib.h>
@@ -82,6 +130,8 @@
 #include <ctype.h>
 #include <math.h>
 #include <errno.h>
+#include <assert.h>
+#include <stdint.h>
 
 #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
 #  include <config.h>
@@ -96,6 +146,25 @@
 #  include "../../png.h"
 #endif
 
+#include <zlib.h>
+
+/* Work round for GCC complaints about casting a (double) function result to
+ * an unsigned:
+ */
+static unsigned int
+flooru(double d)
+{
+   d = floor(d);
+   return (unsigned int)d;
+}
+
+static png_byte
+floorb(double d)
+{
+   d = floor(d);
+   return (png_byte)d;
+}
+
 /* This structure is used for inserting extra chunks (the --insert argument, not
  * documented above.)
  */
@@ -107,7 +176,7 @@ typedef struct chunk_insert
    png_charp            parameters[1];
 } chunk_insert;
 
-static int
+static unsigned int
 channels_of_type(int color_type)
 {
    if (color_type & PNG_COLOR_MASK_PALETTE)
@@ -128,14 +197,15 @@ channels_of_type(int color_type)
    }
 }
 
-static int
+static unsigned int
 pixel_depth_of_type(int color_type, int bit_depth)
 {
    return channels_of_type(color_type) * bit_depth;
 }
 
 static unsigned int
-image_size_of_type(int color_type, int bit_depth, unsigned int *colors)
+image_size_of_type(int color_type, int bit_depth, unsigned int *colors,
+   int small)
 {
    if (*colors)
       return 16;
@@ -144,7 +214,16 @@ image_size_of_type(int color_type, int bit_depth, unsigned int *colors)
    {
       int pixel_depth = pixel_depth_of_type(color_type, bit_depth);
 
-      if (pixel_depth < 8)
+      if (small)
+      {
+         if (pixel_depth <= 8) /* there will be one row */
+            return 1 << pixel_depth;
+
+         else
+            return 256;
+      }
+
+      else if (pixel_depth < 8)
          return 64;
 
       else if (pixel_depth > 16)
@@ -217,7 +296,8 @@ generate_palette(png_colorp palette, png_bytep trans, int bit_depth,
          else
          {
             unsigned int size = 1U << (bit_depth/2); /* 2, 4 or 16 */
-            unsigned int x, y, ip;
+            unsigned int x, y;
+            volatile unsigned int ip = 0;
 
             for (x=0; x<size; ++x) for (y=0; y<size; ++y)
             {
@@ -281,7 +361,7 @@ set_value(png_bytep row, size_t rowbytes, png_uint_32 x, unsigned int bit_depth,
                exit(1);
 
             case 16:
-               value = (unsigned int)floor(65535*pow(value/65535.,conv)+.5);
+               value = flooru(65535*pow(value/65535.,conv)+.5);
                *row++ = (png_byte)(value >> 8);
                *row = (png_byte)value;
                return;
@@ -306,15 +386,148 @@ set_value(png_bytep row, size_t rowbytes, png_uint_32 x, unsigned int bit_depth,
    }
 }
 
-static void
+static int /* filter mask for row */
 generate_row(png_bytep row, size_t rowbytes, unsigned int y, int color_type,
    int bit_depth, png_const_bytep gamma_table, double conv,
-   unsigned int *colors)
+   unsigned int *colors, int small)
 {
-   png_uint_32 size_max = image_size_of_type(color_type, bit_depth, colors)-1;
+   int filters = 0; /* file *MASK*, 0 means the default, not NONE */
+   png_uint_32 size_max = 
+      image_size_of_type(color_type, bit_depth, colors, small)-1;
    png_uint_32 depth_max = (1U << bit_depth)-1; /* up to 65536 */
 
-   if (colors[0] == 0) switch (channels_of_type(color_type))
+   if (colors[0] == 0) if (small)
+   {
+      unsigned int pixel_depth = pixel_depth_of_type(color_type, bit_depth);
+
+      /* For pixel depths less than 16 generate a single row containing all the
+       * possible pixel values.  For 16 generate all 65536 byte pair
+       * combinations in a 256x256 pixel array.
+       */
+      switch (pixel_depth)
+      {
+         case 1:
+            assert(y == 0 && rowbytes == 1 && size_max == 1);
+            row[0] = 0x6CU; /* binary: 01101100, only top 2 bits used */
+            filters = PNG_FILTER_NONE;
+            break;
+
+         case 2:
+            assert(y == 0 && rowbytes == 1 && size_max == 3);
+            row[0] = 0x1BU; /* binary 00011011, all bits used */
+            filters = PNG_FILTER_NONE;
+            break;
+
+         case 4:
+            assert(y == 0 && rowbytes == 8 && size_max == 15);
+            row[0] = 0x01U;
+            row[1] = 0x23U; /* SUB gives 0x22U for all following bytes */
+            row[2] = 0x45U;
+            row[3] = 0x67U;
+            row[4] = 0x89U;
+            row[5] = 0xABU;
+            row[6] = 0xCDU;
+            row[7] = 0xEFU;
+            filters = PNG_FILTER_SUB;
+            break;
+
+         case 8:
+            /* The row will have all the pixel values in order starting with
+             * '1', the SUB filter will change every byte into '1' (including
+             * the last, which generates pixel value '0').  Since the SUB filter
+             * has value 1 this should result in maximum compression.
+             */
+            assert(y == 0 && rowbytes == 256 && size_max == 255);
+            for (;;)
+            {
+               row[size_max] = 0xFFU & (size_max+1);
+               if (size_max == 0)
+                  break;
+               --size_max;
+            }
+            filters = PNG_FILTER_SUB;
+            break;
+
+         case 16:
+            /* Rows are generated such that each row has a constant difference
+             * between the first and second byte of each pixel and so that the
+             * difference increases by 1 at each row.  The rows start with the
+             * first byte value of 0 and the value increases to 255 across the
+             * row.
+             *
+             * The difference starts at 1, so the first row is:
+             *
+             *     0 1 1 2 2 3 3 4 ... 254 255 255 0
+             *
+             * This means that running the SUB filter on the first row produces:
+             *
+             *   [SUB==1] 0 1 0 1 0 1...
+             *
+             * Then the difference is 2 on the next row, giving:
+             *
+             *    0 2 1 3 2 4 3 5 ... 254 0 255 1
+             *
+             * When the UP filter is run on this libpng produces:
+             *
+             *   [UP ==2] 0 1 0 1 0 1...
+             *
+             * And so on for all the remain rows to the final two * rows:
+             *
+             *    row 254: 0 255 1 0 2 1 3 2 4 3 ... 254 253 255 254
+             *    row 255: 0   0 1 1 2 2 3 3 4 4 ... 254 254 255 255
+             */
+            assert(rowbytes == 512 && size_max == 255);
+            for (;;)
+            {
+               row[2*size_max  ] = 0xFFU & size_max;
+               row[2*size_max+1] = 0xFFU & (size_max+y+1);
+               if (size_max == 0)
+                  break;
+               --size_max;
+            }
+            /* The first row must include PNG_FILTER_UP so that libpng knows we
+             * need to keep it for the following row:
+             */
+            filters = (y == 0 ? PNG_FILTER_SUB+PNG_FILTER_UP : PNG_FILTER_UP);
+            break;
+
+         case 24:
+         case 32:
+         case 48:
+         case 64:
+            /* The rows are filled by an alogorithm similar to the above, in the
+             * first row pixel bytes are all equal, increasing from 0 by 1 for
+             * each pixel.  In the second row the bytes within a pixel are
+             * incremented 1,3,5,7,... from the previous row byte.  Using an odd
+             * number ensures all the possible byte values are used.
+             */
+            assert(size_max == 255 && rowbytes == 256*(pixel_depth>>3));
+            pixel_depth >>= 3; /* now in bytes */
+            while (rowbytes > 0)
+            {
+               const size_t pixel_index = --rowbytes/pixel_depth;
+
+               if (y == 0)
+                  row[rowbytes] = 0xFFU & pixel_index;
+
+               else
+               {
+                  const size_t byte_offset =
+                     rowbytes - pixel_index * pixel_depth;
+
+                  row[rowbytes] =
+                     0xFFU & (pixel_index + (byte_offset * 2*y) + 1);
+               }
+            }
+            filters = (y == 0 ? PNG_FILTER_SUB+PNG_FILTER_UP : PNG_FILTER_UP);
+            break;
+
+         default:
+            assert(0/*NOT REACHED*/);
+      }
+   }
+      
+   else switch (channels_of_type(color_type))
    {
    /* 1 channel: a square image with a diamond, the least luminous colors are on
     *    the edge of the image, the most luminous in the center.
@@ -526,6 +739,8 @@ generate_row(png_bytep row, size_t rowbytes, unsigned int y, int color_type,
          colors[0], channels_of_type(color_type));
       exit(1);
    }
+
+   return filters;
 }
 
 
@@ -554,7 +769,7 @@ makepng_error(png_structp png_ptr, png_const_charp message)
 static int /* 0 on success, else an error code */
 write_png(const char **name, FILE *fp, int color_type, int bit_depth,
    volatile png_fixed_point gamma, chunk_insert * volatile insert,
-   unsigned int filters, unsigned int *colors)
+   unsigned int filters, unsigned int *colors, int small, int tRNS)
 {
    png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
       name, makepng_error, makepng_warning);
@@ -581,6 +796,15 @@ write_png(const char **name, FILE *fp, int color_type, int bit_depth,
 
    /* Allow benign errors so that we can write PNGs with errors */
    png_set_benign_errors(png_ptr, 1/*allowed*/);
+
+   /* Max out the text compression level in an attempt to make the license
+    * small.   If --small then do the same for the IDAT.
+    */
+   if (small)
+      png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
+
+   png_set_text_compression_level(png_ptr, Z_BEST_COMPRESSION);
+
    png_init_io(png_ptr, fp);
 
    info_ptr = png_create_info_struct(png_ptr);
@@ -588,11 +812,37 @@ write_png(const char **name, FILE *fp, int color_type, int bit_depth,
       png_error(png_ptr, "OOM allocating info structure");
 
    {
-      unsigned int size = image_size_of_type(color_type, bit_depth, colors);
+      const unsigned int size =
+         image_size_of_type(color_type, bit_depth, colors, small);
+      unsigned int ysize;
       png_fixed_point real_gamma = 45455; /* For sRGB */
       png_byte gamma_table[256];
       double conv;
 
+      /* Normally images are square, but with 'small' we want to simply generate
+       * all the pixel values, or all that we reasonably can:
+       */
+      if (small)
+      {
+         const unsigned int pixel_depth =
+            pixel_depth_of_type(color_type, bit_depth);
+
+         if (pixel_depth <= 8U)
+         {
+            assert(size == (1U<<pixel_depth));
+            ysize = 1U;
+         }
+
+         else
+         {
+            assert(size == 256U);
+            ysize = 256U;
+         }
+      }
+
+      else
+         ysize = size;
+
       /* This function uses the libpng values used on read to carry extra
        * information about the gamma:
        */
@@ -625,13 +875,13 @@ write_png(const char **name, FILE *fp, int color_type, int bit_depth,
             gamma_table[0] = 0;
 
             for (i=1; i<255; ++i)
-               gamma_table[i] = (png_byte)floor(pow(i/255.,conv) * 255 + .5);
+               gamma_table[i] = floorb(pow(i/255.,conv) * 255 + .5);
 
             gamma_table[255] = 255;
          }
       }
 
-      png_set_IHDR(png_ptr, info_ptr, size, size, bit_depth, color_type,
+      png_set_IHDR(png_ptr, info_ptr, size, ysize, bit_depth, color_type,
          PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
 
       if (color_type & PNG_COLOR_MASK_PALETTE)
@@ -643,14 +893,26 @@ write_png(const char **name, FILE *fp, int color_type, int bit_depth,
          npalette = generate_palette(palette, trans, bit_depth, gamma_table,
             colors);
          png_set_PLTE(png_ptr, info_ptr, palette, npalette);
-         png_set_tRNS(png_ptr, info_ptr, trans, npalette-1,
-            NULL/*transparent color*/);
+
+         if (tRNS)
+            png_set_tRNS(png_ptr, info_ptr, trans, npalette-1,
+               NULL/*transparent color*/);
 
          /* Reset gamma_table to prevent the image rows being changed */
          for (npalette=0; npalette<256; ++npalette)
             gamma_table[npalette] = (png_byte)npalette;
       }
 
+      else if (tRNS)
+      {
+         png_color_16 col;
+
+         col.red = col.green = col.blue = col.gray =
+            0x0101U & ((1U<<bit_depth)-1U);
+         col.index = 0U;
+         png_set_tRNS(png_ptr, info_ptr, NULL/*trans*/, 1U, &col);
+      }
+
       if (gamma == PNG_DEFAULT_sRGB)
          png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_ABSOLUTE);
 
@@ -682,7 +944,11 @@ write_png(const char **name, FILE *fp, int color_type, int bit_depth,
       png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, filters);
 
       {
-         int passes = png_set_interlace_handling(png_ptr);
+#        ifdef PNG_WRITE_INTERLACING_SUPPORTED
+            int passes = png_set_interlace_handling(png_ptr);
+#        else /* !WRITE_INTERLACING */
+            int passes = 1;
+#        endif /* !WRITE_INTERLACING */
          int pass;
          png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);
 
@@ -695,10 +961,15 @@ write_png(const char **name, FILE *fp, int color_type, int bit_depth,
          {
             unsigned int y;
 
-            for (y=0; y<size; ++y)
+            for (y=0; y<ysize; ++y)
             {
-               generate_row(row, rowbytes, y, color_type, bit_depth,
-                  gamma_table, conv, colors);
+               unsigned int row_filters =
+                  generate_row(row, rowbytes, y, color_type, bit_depth,
+                        gamma_table, conv, colors, small);
+
+               if (row_filters != 0 && filters == PNG_ALL_FILTERS)
+                  png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, row_filters);
+
                png_write_row(png_ptr, row);
             }
          }
@@ -827,7 +1098,7 @@ static png_size_t
 load_fake(png_charp param, png_bytepp profile)
 {
    char *endptr = NULL;
-   unsigned long long int size = strtoull(param, &endptr, 0/*base*/);
+   uint64_t size = strtoull(param, &endptr, 0/*base*/);
 
    /* The 'fake' format is <number>*[string] */
    if (endptr != NULL && *endptr == '*')
@@ -1062,7 +1333,8 @@ insert_iTXt(png_structp png_ptr, png_infop info_ptr, int nparams,
 }
 
 static void
-insert_hIST(png_structp png_ptr, png_infop info_ptr, int nparams, png_charpp params)
+insert_hIST(png_structp png_ptr, png_infop info_ptr, int nparams,
+      png_charpp params)
 {
    int i;
    png_uint_16 freq[256];
@@ -1231,6 +1503,80 @@ find_insert(png_const_charp what, png_charp param)
    return NULL;
 }
 
+/* This is necessary because libpng expects writeable strings for things like
+ * text chunks (maybe this should be fixed...)
+ */
+static png_charp
+strstash(png_const_charp foo)
+{
+   /* The program indicates a memory allocation error by crashing, this is by
+    * design.
+    */
+   if (foo != NULL)
+   {
+      png_charp bar = malloc(strlen(foo)+1);
+      return strcpy(bar, foo);
+   }
+
+   return NULL;
+}
+
+static png_charp
+strstash_list(const png_const_charp *text)
+{
+   size_t foo = 0;
+   png_charp result, bar;
+   const png_const_charp *line = text;
+
+   while (*line != NULL)
+      foo += strlen(*line++);
+
+   result = bar = malloc(foo+1);
+
+   line = text;
+   while (*line != NULL)
+   {
+      foo = strlen(*line);
+      memcpy(bar, *line++, foo);
+      bar += foo;
+   }
+
+   *bar = 0;
+   return result;
+}
+
+/* These are used to insert Copyright and Licence fields, they allow the text to
+ * have \n unlike the --insert option.
+ */
+static chunk_insert *
+add_tEXt(const char *key, const png_const_charp *text)
+{
+   static char what[5] = { 116, 69, 88, 116, 0 };
+   png_charp parameter_list[3];
+
+   parameter_list[0] = strstash(key);
+   parameter_list[1] = strstash_list(text);
+   parameter_list[2] = NULL;
+
+   return make_insert(what, insert_tEXt, 2, parameter_list);
+}
+
+static chunk_insert *
+add_iTXt(const char *key, const char *language, const char *language_key,
+      const png_const_charp *text)
+{
+   static char what[5] = { 105, 84, 88, 116, 0 };
+   png_charp parameter_list[5];
+
+   parameter_list[0] = strstash(key);
+   parameter_list[1] = strstash(language);
+   parameter_list[2] = strstash(language_key);
+   parameter_list[3] = strstash_list(text);
+   parameter_list[4] = NULL;
+
+   return make_insert(what, insert_iTXt, 4, parameter_list);
+}
+
 /* This is a not-very-good parser for a sequence of numbers (including 0).  It
  * doesn't accept some apparently valid things, but it accepts all the sensible
  * combinations.
@@ -1280,6 +1626,8 @@ main(int argc, char **argv)
    const char *file_name = NULL;
    int color_type = 8; /* invalid */
    int bit_depth = 32; /* invalid */
+   int small = 0; /* make full size images */
+   int tRNS = 0; /* don't output a tRNS chunk */
    unsigned int colors[5];
    unsigned int filters = PNG_ALL_FILTERS;
    png_fixed_point gamma = 0; /* not set */
@@ -1292,6 +1640,18 @@ main(int argc, char **argv)
    {
       char *arg = *++argv;
 
+      if (strcmp(arg, "--small") == 0)
+      {
+         small = 1;
+         continue;
+      }
+
+      if (strcmp(arg, "--tRNS") == 0)
+      {
+         tRNS = 1;
+         continue;
+      }
+
       if (strcmp(arg, "--sRGB") == 0)
       {
          gamma = PNG_DEFAULT_sRGB;
@@ -1432,9 +1792,10 @@ main(int argc, char **argv)
 
    if (color_type == 8 || bit_depth == 32)
    {
-      fprintf(stderr, "usage: makepng [--sRGB|--linear|--1.8] "
+      fprintf(stderr, "usage: makepng [--small] [--sRGB|--linear|--1.8] "
          "[--color=...] color-type bit-depth [file-name]\n"
-         "  Make a test PNG file, by default writes to stdout.\n");
+         "  Make a test PNG file, by default writes to stdout.\n"
+         "  Other options are available, UTSL.\n");
       exit(1);
    }
 
@@ -1453,10 +1814,19 @@ main(int argc, char **argv)
          }
    }
 
+   /* small and colors are incomparible (will probably crash if both are used at
+    * the same time!)
+    */
+   if (small && colors[0] != 0)
+   {
+      fprintf(stderr, "makepng: --color --small: only one at a time!\n");
+      exit(1);
+   }
+
    /* Restrict the filters for more speed to those we know are used for the
     * generated images.
     */
-   if (filters == PNG_ALL_FILTERS)
+   if (filters == PNG_ALL_FILTERS && !small/*small provides defaults*/)
    {
       if ((color_type & PNG_COLOR_MASK_PALETTE) != 0 || bit_depth < 8)
          filters = PNG_FILTER_NONE;
@@ -1474,9 +1844,39 @@ main(int argc, char **argv)
          filters &= ~PNG_FILTER_NONE;
    }
 
+   /* Insert standard copyright and licence text. */
+   {
+      static png_const_charp copyright[] =
+      {
+         COPYRIGHT, /* ISO-Latin-1 */
+         NULL
+      };
+      static png_const_charp licensing[] =
+      {
+         IMAGE_LICENSING, /* UTF-8 */
+         NULL
+      };
+
+      chunk_insert *new_insert;
+      
+      new_insert = add_tEXt("Copyright", copyright);
+      if (new_insert != NULL)
+      {
+         *insert_ptr = new_insert;
+         insert_ptr = &new_insert->next;
+      }
+
+      new_insert = add_iTXt("Licensing", "en", NULL, licensing);
+      if (new_insert != NULL)
+      {
+         *insert_ptr = new_insert;
+         insert_ptr = &new_insert->next;
+      }
+   }
+
    {
       int ret = write_png(&file_name, fp, color_type, bit_depth, gamma,
-         head_insert, filters, colors);
+         head_insert, filters, colors, small, tRNS);
 
       if (ret != 0 && file_name != NULL)
          remove(file_name);
diff --git a/contrib/libtests/pngimage.c b/contrib/libtests/pngimage.c
index 180cf0a16..fe0a3273a 100644
--- a/contrib/libtests/pngimage.c
+++ b/contrib/libtests/pngimage.c
@@ -2,7 +2,7 @@
  *
  * Copyright (c) 2015 John Cunningham Bowler
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -236,10 +236,12 @@ static struct transform_info
        */
 #endif
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-   T(SCALE_16,            NONE, X,   X,   16,  R)
+   T(SCALE_16,            NONE, X,   X,   16,  R),
       /* scales 16-bit components to 8-bits. */
 #endif
 
+   { NULL /*name*/, 0, 0, 0, 0, 0, 0, 0/*!tested*/ }
+
 #undef T
 };
 
@@ -294,7 +296,7 @@ transform_name(int t)
 
    t &= -t; /* first set bit */
 
-   for (i=0; i<TTABLE_SIZE; ++i)
+   for (i=0; i<TTABLE_SIZE; ++i) if (transform_info[i].name != NULL)
    {
       if ((transform_info[i].transform & t) != 0)
          return transform_info[i].name;
@@ -315,7 +317,7 @@ validate_T(void)
 {
    unsigned int i;
 
-   for (i=0; i<TTABLE_SIZE; ++i)
+   for (i=0; i<TTABLE_SIZE; ++i) if (transform_info[i].name != NULL)
    {
       if (transform_info[i].when & TRANSFORM_R)
          read_transforms |= transform_info[i].transform;
@@ -505,6 +507,7 @@ typedef enum
 #define SKIP_BUGS       0x100 /* Skip over known bugs */
 #define LOG_SKIPPED     0x200 /* Log skipped bugs */
 #define FIND_BAD_COMBOS 0x400 /* Attempt to deduce bad combos */
+#define LIST_COMBOS     0x800 /* List combos by name */
 
 /* Result masks apply to the result bits in the 'results' field below; these
  * bits are simple 1U<<error_level.  A pass requires either nothing worse than
@@ -690,7 +693,35 @@ display_log(struct display *dp, error_level level, const char *fmt, ...)
          int tr = dp->transforms;
 
          if (is_combo(tr))
-            fprintf(stderr, "(0x%x)", tr);
+         {
+            if (dp->options & LIST_COMBOS)
+            {
+               int trx = tr;
+
+               fprintf(stderr, "(");
+               if (trx)
+               {
+                  int start = 0;
+
+                  while (trx)
+                  {
+                     int trz = trx & -trx;
+
+                     if (start) fprintf(stderr, "+");
+                     fprintf(stderr, "%s", transform_name(trz));
+                     start = 1;
+                     trx &= ~trz;
+                  }
+               }
+
+               else
+                  fprintf(stderr, "-");
+               fprintf(stderr, ")");
+            }
+
+            else
+               fprintf(stderr, "(0x%x)", tr);
+         }
 
          else
             fprintf(stderr, "(%s)", transform_name(tr));
@@ -910,7 +941,7 @@ update_display(struct display *dp)
       int bd = dp->bit_depth;
       unsigned int i;
 
-      for (i=0; i<TTABLE_SIZE; ++i)
+      for (i=0; i<TTABLE_SIZE; ++i) if (transform_info[i].name != NULL)
       {
          int transform = transform_info[i].transform;
 
@@ -935,9 +966,6 @@ update_display(struct display *dp)
 
       dp->active_transforms = active;
       dp->ignored_transforms = inactive; /* excluding write-only transforms */
-
-      if (active == 0)
-         display_log(dp, INTERNAL_ERROR, "bad transform table");
    }
 }
 
@@ -1588,6 +1616,12 @@ main(const int argc, const char * const * const argv)
       else if (strcmp(name, "--nofind-bad-combos") == 0)
          d.options &= ~FIND_BAD_COMBOS;
 
+      else if (strcmp(name, "--list-combos") == 0)
+         d.options |= LIST_COMBOS;
+
+      else if (strcmp(name, "--nolist-combos") == 0)
+         d.options &= ~LIST_COMBOS;
+
       else if (name[0] == '-' && name[1] == '-')
       {
          fprintf(stderr, "pngimage: %s: unknown option\n", name);
diff --git a/contrib/libtests/pngstest-errors.h b/contrib/libtests/pngstest-errors.h
new file mode 100644
index 000000000..3356f1c46
--- /dev/null
+++ b/contrib/libtests/pngstest-errors.h
@@ -0,0 +1,165 @@
+/* contrib/libtests/pngstest-errors.h
+ *
+ * BUILT USING: libpng version 1.6.19beta03 - September 25, 2015
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * THIS IS A MACHINE GENERATED FILE: do not edit it directly!
+ * Instead run:
+ *
+ *    pngstest --accumulate
+ *
+ * on as many PNG files as possible; at least PNGSuite and
+ * contrib/libtests/testpngs.
+ */
+static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =
+{
+ { /* input: sRGB-gray */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 372, 0 }, { 0, 0, 372, 0 }, { 0, 0, 372, 0 }, { 0, 0, 372, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: sRGB-gray+alpha */
+  { 0, 19, 0, 0 }, { 0, 0, 0, 0 }, { 0, 20, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 897, 788, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: sRGB-rgb */
+  { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 893, 0 }, { 0, 0, 893, 0 }, { 0, 0, 811, 0 }, { 0, 0, 811, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: sRGB-rgb+alpha */
+  { 0, 16, 17, 0 }, { 0, 17, 17, 0 }, { 0, 19, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 850, 875, 0 }, { 0, 850, 875, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-gray */
+  { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-gray+alpha */
+  { 0, 74, 9, 0 }, { 0, 20, 9, 0 }, { 0, 74, 9, 0 }, { 0, 20, 9, 0 },
+  { 0, 0, 0, 0 }, { 0, 1, 0, 0 }, { 0, 0, 0, 0 }, { 0, 1, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-rgb */
+  { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+  { 0, 0, 4, 0 }, { 0, 0, 4, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-rgb+alpha */
+  { 0, 126, 143, 0 }, { 0, 11, 7, 0 }, { 0, 74, 9, 0 }, { 0, 17, 9, 0 },
+  { 0, 4, 4, 0 }, { 0, 5, 4, 0 }, { 0, 0, 0, 0 }, { 0, 1, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-gray */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-gray+alpha */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-rgb */
+  { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+  { 0, 0, 673, 0 }, { 0, 0, 673, 0 }, { 0, 0, 674, 0 }, { 0, 0, 674, 0 },
+  { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 460, 0 }, { 0, 0, 460, 0 }, { 0, 0, 263, 0 }, { 0, 0, 263, 0 }
+ }, { /* input: color-mapped-sRGB-rgb+alpha */
+  { 0, 6, 8, 0 }, { 0, 7, 8, 0 }, { 0, 75, 9, 0 }, { 0, 9, 9, 0 },
+  { 0, 585, 427, 0 }, { 0, 585, 427, 0 }, { 0, 717, 514, 0 }, { 0, 717, 514, 0 },
+  { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 13323, 460, 0 }, { 0, 427, 460, 0 }, { 0, 16480, 263, 0 }, { 0, 243, 263, 0 }
+ }, { /* input: color-mapped-linear-gray */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 282, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-gray+alpha */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 253, 282, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 265, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb+alpha */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 243, 265, 0 }
+ }
+};
+static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =
+{
+ { /* input: sRGB-gray */
+  { 0, 0, 7, 0 }, { 0, 0, 7, 0 }, { 0, 0, 7, 0 }, { 0, 0, 7, 0 }
+ }, { /* input: sRGB-gray+alpha */
+  { 0, 15, 15, 0 }, { 0, 186, 15, 0 }, { 0, 15, 15, 0 }, { 0, 186, 15, 0 }
+ }, { /* input: sRGB-rgb */
+  { 0, 0, 20, 0 }, { 0, 0, 20, 0 }, { 0, 0, 15, 0 }, { 0, 0, 15, 0 }
+ }, { /* input: sRGB-rgb+alpha */
+  { 0, 16, 17, 0 }, { 0, 187, 17, 0 }, { 0, 15, 15, 0 }, { 0, 186, 15, 0 }
+ }, { /* input: linear-gray */
+  { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
+ }, { /* input: linear-gray+alpha */
+  { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }
+ }, { /* input: linear-rgb */
+  { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
+ }, { /* input: linear-rgb+alpha */
+  { 0, 1, 1, 0 }, { 0, 9, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }
+ }, { /* input: color-mapped-sRGB-gray */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-gray+alpha */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-rgb */
+  { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 14, 0 }, { 0, 0, 14, 0 }
+ }, { /* input: color-mapped-sRGB-rgb+alpha */
+  { 0, 4, 8, 0 }, { 0, 9, 8, 0 }, { 0, 9, 5, 0 }, { 0, 32, 5, 0 }
+ }, { /* input: color-mapped-linear-gray */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-gray+alpha */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb+alpha */
+  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }
+};
+static png_uint_16 gpc_error_to_colormap[8/*i*/][8/*o*/][4] =
+{
+ { /* input: sRGB-gray */
+  { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+  { 0, 0, 560, 0 }, { 0, 0, 560, 0 }, { 0, 0, 560, 0 }, { 0, 0, 560, 0 }
+ }, { /* input: sRGB-gray+alpha */
+  { 0, 19, 9, 0 }, { 0, 255, 9, 25 }, { 0, 88, 9, 0 }, { 0, 255, 9, 25 },
+  { 0, 1012, 928, 0 }, { 0, 16026, 928, 6425 }, { 0, 1012, 928, 0 }, { 0, 16026, 928, 6425 }
+ }, { /* input: sRGB-rgb */
+  { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 25, 0 }, { 0, 0, 25, 0 },
+  { 0, 0, 962, 0 }, { 0, 0, 962, 0 }, { 0, 0, 13677, 0 }, { 0, 0, 13677, 0 }
+ }, { /* input: sRGB-rgb+alpha */
+  { 0, 63, 77, 0 }, { 0, 255, 19, 25 }, { 0, 225, 25, 0 }, { 0, 255, 25, 67 },
+  { 0, 17534, 18491, 0 }, { 0, 15736, 2824, 6425 }, { 0, 14019, 13677, 0 }, { 0, 50115, 13677, 17219 }
+ }, { /* input: linear-gray */
+  { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 73, 0 },
+  { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }
+ }, { /* input: linear-gray+alpha */
+  { 0, 74, 74, 0 }, { 0, 255, 74, 25 }, { 0, 99, 74, 0 }, { 0, 255, 74, 25 },
+  { 0, 18919, 18907, 0 }, { 0, 24549, 18907, 6553 }, { 0, 18919, 18907, 0 }, { 0, 24549, 18907, 6553 }
+ }, { /* input: linear-rgb */
+  { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 98, 0 }, { 0, 0, 98, 0 },
+  { 0, 0, 18664, 0 }, { 0, 0, 18664, 0 }, { 0, 0, 24998, 0 }, { 0, 0, 24998, 0 }
+ }, { /* input: linear-rgb+alpha */
+  { 0, 181, 196, 0 }, { 0, 255, 61, 25 }, { 206, 187, 98, 0 }, { 0, 255, 98, 67 },
+  { 0, 18141, 18137, 0 }, { 0, 17494, 17504, 6553 }, { 0, 24979, 24992, 0 }, { 0, 49172, 24992, 17347 }
+ }
+};
+/* END MACHINE GENERATED */
diff --git a/contrib/libtests/pngstest.c b/contrib/libtests/pngstest.c
index 5a080b46e..44267b4fb 100644
--- a/contrib/libtests/pngstest.c
+++ b/contrib/libtests/pngstest.c
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2013-2015 John Cunningham Bowler
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [(PENDING RELEASE)]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -1984,156 +1984,7 @@ static void (* const gpc_fn_colormapped[8/*in*/][8/*out*/])
  * gpc_error_to_colormap.
  */
 #if PNG_FORMAT_FLAG_COLORMAP == 8 /* extra check also required */
-/* START MACHINE GENERATED */
-static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =
-{
- { /* input: sRGB-gray */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 372, 0 }, { 0, 0, 372, 0 }, { 0, 0, 372, 0 }, { 0, 0, 372, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: sRGB-gray+alpha */
-  { 0, 18, 0, 0 }, { 0, 0, 0, 0 }, { 0, 20, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 897, 788, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: sRGB-rgb */
-  { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 893, 0 }, { 0, 0, 893, 0 }, { 0, 0, 811, 0 }, { 0, 0, 811, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: sRGB-rgb+alpha */
-  { 0, 4, 13, 0 }, { 0, 14, 13, 0 }, { 0, 19, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 832, 764, 0 }, { 0, 832, 764, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: linear-gray */
-  { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: linear-gray+alpha */
-  { 0, 74, 9, 0 }, { 0, 20, 9, 0 }, { 0, 74, 9, 0 }, { 0, 20, 9, 0 },
-  { 0, 0, 0, 0 }, { 0, 1, 0, 0 }, { 0, 0, 0, 0 }, { 0, 1, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: linear-rgb */
-  { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
-  { 0, 0, 4, 0 }, { 0, 0, 4, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: linear-rgb+alpha */
-  { 0, 126, 143, 0 }, { 0, 9, 7, 0 }, { 0, 74, 9, 0 }, { 0, 16, 9, 0 },
-  { 0, 4, 4, 0 }, { 0, 5, 4, 0 }, { 0, 0, 0, 0 }, { 0, 1, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-sRGB-gray */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-sRGB-gray+alpha */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-sRGB-rgb */
-  { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 8, 0 }, { 0, 0, 8, 0 },
-  { 0, 0, 673, 0 }, { 0, 0, 673, 0 }, { 0, 0, 674, 0 }, { 0, 0, 674, 0 },
-  { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 460, 0 }, { 0, 0, 460, 0 }, { 0, 0, 263, 0 }, { 0, 0, 263, 0 }
- }, { /* input: color-mapped-sRGB-rgb+alpha */
-  { 0, 6, 8, 0 }, { 0, 7, 8, 0 }, { 0, 75, 8, 0 }, { 0, 9, 8, 0 },
-  { 0, 585, 427, 0 }, { 0, 585, 427, 0 }, { 0, 717, 409, 0 }, { 0, 717, 409, 0 },
-  { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 13323, 460, 0 }, { 0, 334, 460, 0 }, { 0, 16480, 263, 0 }, { 0, 243, 263, 0 }
- }, { /* input: color-mapped-linear-gray */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 282, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-linear-gray+alpha */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 253, 282, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-linear-rgb */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 265, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-linear-rgb+alpha */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 243, 265, 0 }
- }
-};
-static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =
-{
- { /* input: sRGB-gray */
-  { 0, 0, 7, 0 }, { 0, 0, 7, 0 }, { 0, 0, 7, 0 }, { 0, 0, 7, 0 }
- }, { /* input: sRGB-gray+alpha */
-  { 0, 15, 15, 0 }, { 0, 186, 15, 0 }, { 0, 15, 15, 0 }, { 0, 186, 15, 0 }
- }, { /* input: sRGB-rgb */
-  { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 15, 0 }, { 0, 0, 15, 0 }
- }, { /* input: sRGB-rgb+alpha */
-  { 0, 12, 14, 0 }, { 0, 180, 14, 0 }, { 0, 14, 15, 0 }, { 0, 186, 15, 0 }
- }, { /* input: linear-gray */
-  { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
- }, { /* input: linear-gray+alpha */
-  { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }
- }, { /* input: linear-rgb */
-  { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
- }, { /* input: linear-rgb+alpha */
-  { 0, 1, 1, 0 }, { 0, 8, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }
- }, { /* input: color-mapped-sRGB-gray */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-sRGB-gray+alpha */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-sRGB-rgb */
-  { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 14, 0 }, { 0, 0, 14, 0 }
- }, { /* input: color-mapped-sRGB-rgb+alpha */
-  { 0, 4, 8, 0 }, { 0, 9, 8, 0 }, { 0, 8, 3, 0 }, { 0, 32, 3, 0 }
- }, { /* input: color-mapped-linear-gray */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-linear-gray+alpha */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-linear-rgb */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }, { /* input: color-mapped-linear-rgb+alpha */
-  { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
- }
-};
-static png_uint_16 gpc_error_to_colormap[8/*i*/][8/*o*/][4] =
-{
- { /* input: sRGB-gray */
-  { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
-  { 0, 0, 560, 0 }, { 0, 0, 560, 0 }, { 0, 0, 560, 0 }, { 0, 0, 560, 0 }
- }, { /* input: sRGB-gray+alpha */
-  { 0, 19, 2, 0 }, { 0, 255, 2, 25 }, { 0, 88, 2, 0 }, { 0, 255, 2, 25 },
-  { 0, 1012, 745, 0 }, { 0, 16026, 745, 6425 }, { 0, 1012, 745, 0 }, { 0, 16026, 745, 6425 }
- }, { /* input: sRGB-rgb */
-  { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 25, 0 }, { 0, 0, 25, 0 },
-  { 0, 0, 937, 0 }, { 0, 0, 937, 0 }, { 0, 0, 13677, 0 }, { 0, 0, 13677, 0 }
- }, { /* input: sRGB-rgb+alpha */
-  { 0, 63, 77, 0 }, { 0, 255, 19, 25 }, { 0, 220, 25, 0 }, { 0, 255, 25, 67 },
-  { 0, 17534, 18491, 0 }, { 0, 15614, 2824, 6425 }, { 0, 14019, 13677, 0 }, { 0, 48573, 13677, 17219 }
- }, { /* input: linear-gray */
-  { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 73, 0 },
-  { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }
- }, { /* input: linear-gray+alpha */
-  { 0, 74, 74, 0 }, { 0, 255, 74, 25 }, { 0, 97, 74, 0 }, { 0, 255, 74, 25 },
-  { 0, 18919, 18907, 0 }, { 0, 24549, 18907, 6552 }, { 0, 18919, 18907, 0 }, { 0, 24549, 18907, 6552 }
- }, { /* input: linear-rgb */
-  { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 98, 0 }, { 0, 0, 98, 0 },
-  { 0, 0, 18664, 0 }, { 0, 0, 18664, 0 }, { 0, 0, 24998, 0 }, { 0, 0, 24998, 0 }
- }, { /* input: linear-rgb+alpha */
-  { 0, 181, 196, 0 }, { 0, 255, 61, 25 }, { 206, 187, 98, 0 }, { 0, 255, 98, 67 },
-  { 0, 18141, 18137, 0 }, { 0, 17494, 17504, 6553 }, { 0, 24979, 24992, 0 }, { 0, 46509, 24992, 17347 }
- }
-};
-/* END MACHINE GENERATED */
+#  include "pngstest-errors.h" /* machine generated */
 #endif /* COLORMAP flag check */
 #endif /* flag checks */
 
@@ -2154,7 +2005,7 @@ typedef struct
    int          in_opaque;   /* Value of input alpha that is opaque */
    int          is_palette;  /* Sample values come from the palette */
    int          accumulate;  /* Accumlate component errors (don't log) */
-   int          output_8bit; /* Output is 8 bit (else 16 bit) */
+   int          output_8bit; /* Output is 8-bit (else 16-bit) */
 
    void (*in_gp)(Pixel*, png_const_voidp);
    void (*out_gp)(Pixel*, png_const_voidp);
@@ -3722,6 +3573,23 @@ main(int argc, char **argv)
    {
       unsigned int in;
 
+      printf("/* contrib/libtests/pngstest-errors.h\n");
+      printf(" *\n");
+      printf(" * BUILT USING:" PNG_HEADER_VERSION_STRING);
+      printf(" *\n");
+      printf(" * This code is released under the libpng license.\n");
+      printf(" * For conditions of distribution and use, see the disclaimer\n");
+      printf(" * and license in png.h\n");
+      printf(" *\n");
+      printf(" * THIS IS A MACHINE GENERATED FILE: do not edit it directly!\n");
+      printf(" * Instead run:\n");
+      printf(" *\n");
+      printf(" *    pngstest --accumulate\n");
+      printf(" *\n");
+      printf(" * on as many PNG files as possible; at least PNGSuite and\n");
+      printf(" * contrib/libtests/testpngs.\n");
+      printf(" */\n");
+
       printf("static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =\n");
       printf("{\n");
       for (in=0; in<16; ++in)
@@ -3811,6 +3679,7 @@ main(int argc, char **argv)
             putchar('\n');
       }
       printf("};\n");
+      printf("/* END MACHINE GENERATED */\n");
    }
 
    if (retval == 0 && touch != NULL)
diff --git a/contrib/libtests/pngunknown.c b/contrib/libtests/pngunknown.c
index 309ee604e..0d52ff8ab 100644
--- a/contrib/libtests/pngunknown.c
+++ b/contrib/libtests/pngunknown.c
@@ -363,7 +363,7 @@ ancillary(const char *name)
    return PNG_CHUNK_ANCILLARY(PNG_U32(name[0], name[1], name[2], name[3]));
 }
 
-#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+#ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
 static int
 ancillaryb(const png_byte *name)
 {
@@ -554,7 +554,7 @@ read_callback(png_structp pp, png_unknown_chunkp pc)
    /* However if there is no support to store unknown chunks don't ask libpng to
     * do it; there will be an png_error.
     */
-#  ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+#  ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
       return discard;
 #  else
       return 1; /*handled; discard*/
@@ -562,7 +562,7 @@ read_callback(png_structp pp, png_unknown_chunkp pc)
 }
 #endif /* READ_USER_CHUNKS_SUPPORTED */
 
-#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+#ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
 static png_uint_32
 get_unknown(display *d, png_infop info_ptr, int after_IDAT)
 {
@@ -722,11 +722,17 @@ check(FILE *fp, int argc, const char **argv, png_uint_32p flags/*out*/,
                    * in this case, so we just check the arguments!  This could
                    * be improved in the future by using the read callback.
                    */
-                  png_byte name[5];
+#                 if PNG_LIBPNG_VER >= 10700 &&\
+                     !defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+                     if (option < PNG_HANDLE_CHUNK_IF_SAFE)
+#                 endif /* 1.7+ SAVE_UNKNOWN_CHUNKS */
+                  {
+                     png_byte name[5];
 
-                  memcpy(name, chunk_info[chunk].name, 5);
-                  png_set_keep_unknown_chunks(d->png_ptr, option, name, 1);
-                  chunk_info[chunk].keep = option;
+                     memcpy(name, chunk_info[chunk].name, 5);
+                     png_set_keep_unknown_chunks(d->png_ptr, option, name, 1);
+                     chunk_info[chunk].keep = option;
+                  }
                   continue;
                }
 
@@ -735,7 +741,12 @@ check(FILE *fp, int argc, const char **argv, png_uint_32p flags/*out*/,
             case 7: /* default */
                if (memcmp(argv[i], "default", 7) == 0)
                {
-                  png_set_keep_unknown_chunks(d->png_ptr, option, NULL, 0);
+#                 if PNG_LIBPNG_VER >= 10700 &&\
+                     !defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+                     if (option < PNG_HANDLE_CHUNK_IF_SAFE)
+#                 endif /* 1.7+ SAVE_UNKNOWN_CHUNKS */
+                     png_set_keep_unknown_chunks(d->png_ptr, option, NULL, 0);
+
                   d->keep = option;
                   continue;
                }
@@ -745,7 +756,12 @@ check(FILE *fp, int argc, const char **argv, png_uint_32p flags/*out*/,
             case 3: /* all */
                if (memcmp(argv[i], "all", 3) == 0)
                {
-                  png_set_keep_unknown_chunks(d->png_ptr, option, NULL, -1);
+#                 if PNG_LIBPNG_VER >= 10700 &&\
+                     !defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+                     if (option < PNG_HANDLE_CHUNK_IF_SAFE)
+#                 endif /* 1.7+ SAVE_UNKNOWN_CHUNKS */
+                     png_set_keep_unknown_chunks(d->png_ptr, option, NULL, -1);
+
                   d->keep = option;
 
                   for (chunk = 0; chunk < NINFO; ++chunk)
@@ -1242,4 +1258,4 @@ main(void)
    /* So the test is skipped: */
    return 77;
 }
-#endif /* SET_UNKNOWN_CHUNKS && READ */
+#endif /* SET_UNKNOWN_CHUNKS && READ*/
diff --git a/contrib/libtests/pngvalid.c b/contrib/libtests/pngvalid.c
index 1efab6453..7cee971bf 100644
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,7 +1,7 @@
 
 /* pngvalid.c - validate libpng by constructing then reading png files.
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.5.24 [(PENDING RELEASE)]
  * Copyright (c) 2014-2015 Glenn Randers-Pehrson
  * Written by John Cunningham Bowler
  *
@@ -74,7 +74,7 @@
    (defined(PNG_FIXED_POINT_SUPPORTED) || defined(PNG_FLOATING_POINT_SUPPORTED))
 
 #if PNG_LIBPNG_VER < 10500
-/* This deliberately lacks the PNG_CONST. */
+/* This deliberately lacks the const. */
 typedef png_byte *png_const_bytep;
 
 /* This is copied from 1.5.1 png.h: */
@@ -116,6 +116,13 @@ typedef png_byte *png_const_bytep;
 #  define png_const_structp png_structp
 #endif
 
+#if PNG_LIBPNG_VER < 10700
+   /* READ_INTERLACING was used instead of READ_DEINTERLACE. */
+#  ifdef PNG_READ_INTERLACING_SUPPORTED
+#     define PNG_READ_DEINTERLACE_SUPPORTED
+#  endif
+#endif
+
 #include <float.h>  /* For floating point constants */
 #include <stdlib.h> /* For malloc */
 #include <string.h> /* For memcpy, memset */
@@ -164,6 +171,24 @@ define_exception_type(struct png_store*);
  */
 #define ARRAY_SIZE(a) ((unsigned int)((sizeof (a))/(sizeof (a)[0])))
 
+/* GCC BUG 66447 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66447) requires
+ * some broken GCC versions to be fixed up to avoid invalid whining about auto
+ * variables that are *not* changed within the scope of a setjmp being changed.
+ *
+ * Feel free to extend the list of broken versions.
+ */
+#define is_gnu(major,minor)\
+   (defined __GNUC__) && __GNUC__ == (major) && __GNUC_MINOR__ == (minor)
+#define is_gnu_patch(major,minor,patch)\
+   is_gnu(major,minor) && __GNUC_PATCHLEVEL__ == 0
+/* For the moment just do it always; all versions of GCC seem to be broken: */
+#ifdef __GNUC__
+   const void * volatile make_volatile_for_gnu;
+#  define gnu_volatile(x) make_volatile_for_gnu = &x;
+#else /* !GNUC broken versions */
+#  define gnu_volatile(x)
+#endif /* !GNUC broken versions */
+
 /******************************* UTILITIES ************************************/
 /* Error handling is particularly problematic in production code - error
  * handlers often themselves have bugs which lead to programs that detect
@@ -172,7 +197,7 @@ define_exception_type(struct png_store*);
  * warning messages into buffers that are too small.
  */
 static size_t safecat(char *buffer, size_t bufsize, size_t pos,
-   PNG_CONST char *cat)
+   const char *cat)
 {
    while (pos < bufsize && cat != NULL && *cat != 0)
       buffer[pos++] = *cat++;
@@ -201,16 +226,16 @@ static size_t safecatd(char *buffer, size_t bufsize, size_t pos, double d,
 }
 #endif
 
-static PNG_CONST char invalid[] = "invalid";
-static PNG_CONST char sep[] = ": ";
+static const char invalid[] = "invalid";
+static const char sep[] = ": ";
 
-static PNG_CONST char *colour_types[8] =
+static const char *colour_types[8] =
 {
    "grayscale", invalid, "truecolour", "indexed-colour",
    "grayscale with alpha", invalid, "truecolour with alpha", invalid
 };
 
-#ifdef PNG_READ_SUPPORTED
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
 /* Convert a double precision value to fixed point. */
 static png_fixed_point
 fix(double d)
@@ -269,7 +294,7 @@ randomize(void *pv, size_t size)
 #define RANDOMIZE(this) randomize(&(this), sizeof (this))
 #endif /* READ || WRITE_tRNS */
 
-#ifdef PNG_READ_SUPPORTED
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
 static unsigned int
 random_mod(unsigned int max)
 {
@@ -722,7 +747,7 @@ store_pool_mark(png_bytep mark)
    make_four_random_bytes(store_seed, mark);
 }
 
-#ifdef PNG_READ_SUPPORTED
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
 /* Use this for random 32 bit values; this function makes sure the result is
  * non-zero.
  */
@@ -880,7 +905,7 @@ store_storefile(png_store *ps, png_uint_32 id)
 /* Generate an error message (in the given buffer) */
 static size_t
 store_message(png_store *ps, png_const_structp pp, char *buffer, size_t bufsize,
-   size_t pos, PNG_CONST char *msg)
+   size_t pos, const char *msg)
 {
    if (pp != NULL && pp == ps->pread)
    {
@@ -998,7 +1023,7 @@ store_warning(png_structp ppIn, png_const_charp message)
  */
 /* Return a single row from the correct image. */
 static png_bytep
-store_image_row(PNG_CONST png_store* ps, png_const_structp pp, int nImage,
+store_image_row(const png_store* ps, png_const_structp pp, int nImage,
    png_uint_32 y)
 {
    png_size_t coffset = (nImage * ps->image_h + y) * (ps->cb_row + 5) + 2;
@@ -1102,7 +1127,7 @@ store_ensure_image(png_store *ps, png_const_structp pp, int nImages,
 
 #ifdef PNG_READ_SUPPORTED
 static void
-store_image_check(PNG_CONST png_store* ps, png_const_structp pp, int iImage)
+store_image_check(const png_store* ps, png_const_structp pp, int iImage)
 {
    png_const_bytep image = ps->image;
 
@@ -1352,7 +1377,7 @@ typedef struct store_memory
  * all the memory.
  */
 static void
-store_pool_error(png_store *ps, png_const_structp pp, PNG_CONST char *msg)
+store_pool_error(png_store *ps, png_const_structp pp, const char *msg)
 {
    if (pp != NULL)
       png_error(pp, msg);
@@ -1416,7 +1441,7 @@ store_pool_delete(png_store *ps, store_pool *pool)
          next->next = NULL;
 
          fprintf(stderr, "\t%lu bytes @ %p\n",
-             (unsigned long)next->size, (PNG_CONST void*)(next+1));
+             (unsigned long)next->size, (const void*)(next+1));
          /* The NULL means this will always return, even if the memory is
           * corrupted.
           */
@@ -1571,8 +1596,7 @@ store_write_reset(png_store *ps)
  * returned libpng structures as destroyed by store_write_reset above.
  */
 static png_structp
-set_store_for_write(png_store *ps, png_infopp ppi,
-   PNG_CONST char * volatile name)
+set_store_for_write(png_store *ps, png_infopp ppi, const char *name)
 {
    anon_context(ps);
 
@@ -1692,7 +1716,7 @@ store_read_set(png_store *ps, png_uint_32 id)
  */
 static png_structp
 set_store_for_read(png_store *ps, png_infopp ppi, png_uint_32 id,
-   PNG_CONST char *name)
+   const char *name)
 {
    /* Set the name for png_error */
    safecat(ps->test, sizeof ps->test, 0, name);
@@ -1799,6 +1823,7 @@ typedef struct color_encoding
 } color_encoding;
 
 #ifdef PNG_READ_SUPPORTED
+#if defined PNG_READ_TRANSFORMS_SUPPORTED && defined PNG_READ_cHRM_SUPPORTED
 static double
 chromaticity_x(CIE_color c)
 {
@@ -1812,7 +1837,7 @@ chromaticity_y(CIE_color c)
 }
 
 static CIE_color
-white_point(PNG_CONST color_encoding *encoding)
+white_point(const color_encoding *encoding)
 {
    CIE_color white;
 
@@ -1822,12 +1847,13 @@ white_point(PNG_CONST color_encoding *encoding)
 
    return white;
 }
+#endif /* READ_TRANSFORMS && READ_cHRM */
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 static void
 normalize_color_encoding(color_encoding *encoding)
 {
-   PNG_CONST double whiteY = encoding->red.Y + encoding->green.Y +
+   const double whiteY = encoding->red.Y + encoding->green.Y +
       encoding->blue.Y;
 
    if (whiteY != 1)
@@ -1845,9 +1871,10 @@ normalize_color_encoding(color_encoding *encoding)
 }
 #endif
 
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
 static size_t
 safecat_color_encoding(char *buffer, size_t bufsize, size_t pos,
-   PNG_CONST color_encoding *e, double encoding_gamma)
+   const color_encoding *e, double encoding_gamma)
 {
    if (e != 0)
    {
@@ -1884,6 +1911,7 @@ safecat_color_encoding(char *buffer, size_t bufsize, size_t pos,
 
    return pos;
 }
+#endif /* READ_TRANSFORMS */
 #endif /* PNG_READ_SUPPORTED */
 
 typedef struct png_modifier
@@ -1908,9 +1936,9 @@ typedef struct png_modifier
    unsigned int              ngammas;
    unsigned int              ngamma_tests;     /* Number of gamma tests to run*/
    double                    current_gamma;    /* 0 if not set */
-   PNG_CONST color_encoding *encodings;
+   const color_encoding *encodings;
    unsigned int              nencodings;
-   PNG_CONST color_encoding *current_encoding; /* If an encoding has been set */
+   const color_encoding *current_encoding; /* If an encoding has been set */
    unsigned int              encoding_counter; /* For iteration */
    int                       encoding_ignored; /* Something overwrote it */
 
@@ -1921,7 +1949,7 @@ typedef struct png_modifier
    unsigned int              repeat :1;   /* Repeat this transform test. */
    unsigned int              test_uses_encoding :1;
 
-   /* Lowest sbit to test (libpng fails for sbit < 8) */
+   /* Lowest sbit to test (pre-1.7 libpng fails for sbit < 8) */
    png_byte                 sbitlow;
 
    /* Error control - these are the limits on errors accepted by the gamma tests
@@ -2008,7 +2036,7 @@ typedef struct png_modifier
    unsigned int             test_gamma_expand16 :1;
    unsigned int             test_exhaustive :1;
 
-   /* Whether or not to run the low-bit-depth grayscale tests.  This fail on
+   /* Whether or not to run the low-bit-depth grayscale tests.  This fails on
     * gamma images in some cases because of gross inaccuracies in the grayscale
     * gamma handling for low bit depth.
     */
@@ -2125,7 +2153,7 @@ static double digitize(double value, int depth, int do_round)
     * rounding and 'do_round' should be 1, if it is 0 the digitized value will
     * be truncated.
     */
-   PNG_CONST unsigned int digitization_factor = (1U << depth) -1;
+   const unsigned int digitization_factor = (1U << depth) -1;
 
    /* Limiting the range is done as a convenience to the caller - it's easier to
     * do it once here than every time at the call site.
@@ -2144,7 +2172,7 @@ static double digitize(double value, int depth, int do_round)
 #endif /* RGB_TO_GRAY */
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
-static double abserr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
+static double abserr(const png_modifier *pm, int in_depth, int out_depth)
 {
    /* Absolute error permitted in linear values - affected by the bit depth of
     * the calculations.
@@ -2156,7 +2184,7 @@ static double abserr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
       return pm->maxabs8;
 }
 
-static double calcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
+static double calcerr(const png_modifier *pm, int in_depth, int out_depth)
 {
    /* Error in the linear composition arithmetic - only relevant when
     * composition actually happens (0 < alpha < 1).
@@ -2169,7 +2197,7 @@ static double calcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
       return pm->maxcalc8;
 }
 
-static double pcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
+static double pcerr(const png_modifier *pm, int in_depth, int out_depth)
 {
    /* Percentage error permitted in the linear values.  Note that the specified
     * value is a percentage but this routine returns a simple number.
@@ -2192,7 +2220,7 @@ static double pcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
  * The specified parameter does *not* include the base .5 digitization error but
  * it is added here.
  */
-static double outerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
+static double outerr(const png_modifier *pm, int in_depth, int out_depth)
 {
    /* There is a serious error in the 2 and 4 bit grayscale transform because
     * the gamma table value (8 bits) is simply shifted, not rounded, so the
@@ -2224,7 +2252,7 @@ static double outerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
  * rather than raising a warning.  This is useful for debugging to track down
  * exactly what set of parameters cause high error values.
  */
-static double outlog(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
+static double outlog(const png_modifier *pm, int in_depth, int out_depth)
 {
    /* The command line parameters are either 8 bit (0..255) or 16 bit (0..65535)
     * and so must be adjusted for low bit depth grayscale:
@@ -2262,7 +2290,7 @@ static double outlog(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
  * but in the 8 bit calculation case it's actually quantization to a multiple of
  * 257!
  */
-static int output_quantization_factor(PNG_CONST png_modifier *pm, int in_depth,
+static int output_quantization_factor(const png_modifier *pm, int in_depth,
    int out_depth)
 {
    if (out_depth == 16 && in_depth != 16 &&
@@ -2326,7 +2354,7 @@ modification_init(png_modification *pmm)
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 static void
-modifier_current_encoding(PNG_CONST png_modifier *pm, color_encoding *ce)
+modifier_current_encoding(const png_modifier *pm, color_encoding *ce)
 {
    if (pm->current_encoding != 0)
       *ce = *pm->current_encoding;
@@ -2338,9 +2366,10 @@ modifier_current_encoding(PNG_CONST png_modifier *pm, color_encoding *ce)
 }
 #endif
 
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
 static size_t
 safecat_current_encoding(char *buffer, size_t bufsize, size_t pos,
-   PNG_CONST png_modifier *pm)
+   const png_modifier *pm)
 {
    pos = safecat_color_encoding(buffer, bufsize, pos, pm->current_encoding,
       pm->current_gamma);
@@ -2350,6 +2379,7 @@ safecat_current_encoding(char *buffer, size_t bufsize, size_t pos,
 
    return pos;
 }
+#endif
 
 /* Iterate through the usefully testable color encodings.  An encoding is one
  * of:
@@ -2369,7 +2399,7 @@ safecat_current_encoding(char *buffer, size_t bufsize, size_t pos,
  * caller of modifier_reset must reset it at the start of each run of the test!
  */
 static unsigned int
-modifier_total_encodings(PNG_CONST png_modifier *pm)
+modifier_total_encodings(const png_modifier *pm)
 {
    return 1 +                 /* (1) nothing */
       pm->ngammas +           /* (2) gamma values to test */
@@ -2485,14 +2515,14 @@ modifier_set_encoding(png_modifier *pm)
  * assumption below that the first encoding in the list is the one for sRGB.
  */
 static int
-modifier_color_encoding_is_sRGB(PNG_CONST png_modifier *pm)
+modifier_color_encoding_is_sRGB(const png_modifier *pm)
 {
    return pm->current_encoding != 0 && pm->current_encoding == pm->encodings &&
       pm->current_encoding->gamma == pm->current_gamma;
 }
 
 static int
-modifier_color_encoding_is_set(PNG_CONST png_modifier *pm)
+modifier_color_encoding_is_set(const png_modifier *pm)
 {
    return pm->current_gamma != 0;
 }
@@ -2811,7 +2841,7 @@ modifier_progressive_read(png_modifier *pm, png_structp pp, png_infop pi)
 /* Set up a modifier. */
 static png_structp
 set_modifier_for_read(png_modifier *pm, png_infopp ppi, png_uint_32 id,
-    PNG_CONST char *name)
+    const char *name)
 {
    /* Do this first so that the modifier fields are cleared even if an error
     * happens allocating the png_struct.  No allocation is done here so no
@@ -2871,7 +2901,7 @@ gama_modification_init(gama_modification *me, png_modifier *pm, double gammad)
 typedef struct chrm_modification
 {
    png_modification          this;
-   PNG_CONST color_encoding *encoding;
+   const color_encoding *encoding;
    png_fixed_point           wx, wy, rx, ry, gx, gy, bx, by;
 } chrm_modification;
 
@@ -2895,7 +2925,7 @@ chrm_modify(png_modifier *pm, png_modification *me, int add)
 
 static void
 chrm_modification_init(chrm_modification *me, png_modifier *pm,
-   PNG_CONST color_encoding *encoding)
+   const color_encoding *encoding)
 {
    CIE_color white = white_point(encoding);
 
@@ -3232,8 +3262,8 @@ init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
 
 #ifdef PNG_WRITE_tRNS_SUPPORTED
 static void
-set_random_tRNS(png_structp pp, png_infop pi, PNG_CONST png_byte colour_type,
-   PNG_CONST int bit_depth)
+set_random_tRNS(png_structp pp, png_infop pi, const png_byte colour_type,
+   const int bit_depth)
 {
    /* To make this useful the tRNS color needs to match at least one pixel.
     * Random values are fine for gray, including the 16-bit case where we know
@@ -3518,13 +3548,16 @@ transform_row(png_const_structp pp, png_byte buffer[TRANSFORM_ROWMAX],
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
 #  define INTERLACE_LAST PNG_INTERLACE_LAST
 #  define check_interlace_type(type) ((void)(type))
-#else
-#  define INTERLACE_LAST (PNG_INTERLACE_NONE+1)
-#  define png_set_interlace_handling(a) (1)
-
+#  define set_write_interlace_handling(pp,type) png_set_interlace_handling(pp)
+#elif PNG_LIBPNG_VER < 10700
+#  define set_write_interlace_handling(pp,type) (1)
 static void
-check_interlace_type(int PNG_CONST interlace_type)
+check_interlace_type(int const interlace_type)
 {
+   /* Prior to 1.7.0 libpng does not support the write of an interlaced image
+    * unless PNG_WRITE_INTERLACING_SUPPORTED, even with do_interlace so the
+    * code here does the pixel interlace itself, so:
+    */
    if (interlace_type != PNG_INTERLACE_NONE)
    {
       /* This is an internal error - --interlace tests should be skipped, not
@@ -3534,17 +3567,26 @@ check_interlace_type(int PNG_CONST interlace_type)
       exit(99);
    }
 }
-#endif
+#  define INTERLACE_LAST (PNG_INTERLACE_NONE+1)
+#else /* libpng 1.7+ */
+#  define set_write_interlace_handling(pp,type)\
+      npasses_from_interlace_type(pp,type)
+#  define check_interlace_type(type) ((void)(type))
+#  define INTERLACE_LAST (PNG_INTERLACE_NONE+1)
+#endif /* WRITE_INTERLACING tests */
 
-/* Make a standardized image given a an image colour type, bit depth and
+#define CAN_WRITE_INTERLACE\
+   PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
+
+/* Make a standardized image given an image colour type, bit depth and
  * interlace type.  The standard images have a very restricted range of
  * rows and heights and are used for testing transforms rather than image
  * layout details.  See make_size_images below for a way to make images
  * that test odd sizes along with the libpng interlace handling.
  */
 static void
-make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
-    png_byte PNG_CONST bit_depth, unsigned int palette_number,
+make_transform_image(png_store* const ps, png_byte const colour_type,
+    png_byte const bit_depth, unsigned int palette_number,
     int interlace_type, png_const_charp name)
 {
    context(ps, fault);
@@ -3611,7 +3653,7 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
 
       if (png_get_rowbytes(pp, pi) !=
           transform_rowsize(pp, colour_type, bit_depth))
-         png_error(pp, "row size incorrect");
+         png_error(pp, "transform row size incorrect");
 
       else
       {
@@ -3619,7 +3661,7 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
           * because if it is called before, the information in *pp has not been
           * updated to reflect the interlaced image.
           */
-         int npasses = png_set_interlace_handling(pp);
+         int npasses = set_write_interlace_handling(pp, interlace_type);
          int pass;
 
          if (npasses != npasses_from_interlace_type(pp, interlace_type))
@@ -3781,17 +3823,13 @@ size_row(png_byte buffer[SIZE_ROWMAX], png_uint_32 bit_width, png_uint_32 y)
 }
 
 static void
-make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
-    png_byte PNG_CONST bit_depth, int PNG_CONST interlace_type,
-    png_uint_32 PNG_CONST w, png_uint_32 PNG_CONST h,
-    int PNG_CONST do_interlace)
+make_size_image(png_store* const ps, png_byte const colour_type,
+    png_byte const bit_depth, int const interlace_type,
+    png_uint_32 const w, png_uint_32 const h,
+    int const do_interlace)
 {
    context(ps, fault);
 
-   /* At present libpng does not support the write of an interlaced image unless
-    * PNG_WRITE_INTERLACING_SUPPORTED, even with do_interlace so the code here
-    * does the pixel interlace itself, so:
-    */
    check_interlace_type(interlace_type);
 
    Try
@@ -3802,7 +3840,7 @@ make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
 
       /* Make a name and get an appropriate id for the store: */
       char name[FILE_NAME_SIZE];
-      PNG_CONST png_uint_32 id = FILEID(colour_type, bit_depth, 0/*palette*/,
+      const png_uint_32 id = FILEID(colour_type, bit_depth, 0/*palette*/,
          interlace_type, w, h, do_interlace);
 
       standard_name_from_id(name, sizeof name, 0, id);
@@ -3853,7 +3891,7 @@ make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
        */
       pixel_size = bit_size(pp, colour_type, bit_depth);
       if (png_get_rowbytes(pp, pi) != ((w * pixel_size) + 7) / 8)
-         png_error(pp, "row size incorrect");
+         png_error(pp, "size row size incorrect");
 
       else
       {
@@ -3870,7 +3908,8 @@ make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
           */
          memset(image, 0xff, sizeof image);
 
-         if (!do_interlace && npasses != png_set_interlace_handling(pp))
+         if (!do_interlace &&
+             npasses != set_write_interlace_handling(pp, interlace_type))
             png_error(pp, "write: png_set_interlace_handling failed");
 
          /* Prepare the whole image first to avoid making it 7 times: */
@@ -3880,7 +3919,7 @@ make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
          for (pass=0; pass<npasses; ++pass)
          {
             /* The following two are for checking the macros: */
-            PNG_CONST png_uint_32 wPass = PNG_PASS_COLS(w, pass);
+            const png_uint_32 wPass = PNG_PASS_COLS(w, pass);
 
             /* If do_interlace is set we don't call png_write_row for every
              * row because some of them are empty.  In fact, for a 1x1 image,
@@ -3979,8 +4018,8 @@ make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
 }
 
 static void
-make_size(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, int bdlo,
-    int PNG_CONST bdhi)
+make_size(png_store* const ps, png_byte const colour_type, int bdlo,
+    int const bdhi)
 {
    for (; bdlo <= bdhi; ++bdlo)
    {
@@ -4003,6 +4042,11 @@ make_size(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, int bdlo,
 #        ifdef PNG_WRITE_INTERLACING_SUPPORTED
             make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
                width, height, 0);
+#        endif
+#        if CAN_WRITE_INTERLACE
+            /* 1.7.0 removes the hack that prevented app write of an interlaced
+             * image if WRITE_INTERLACING was not supported
+             */
             make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
                width, height, 1);
 #        endif
@@ -4076,34 +4120,34 @@ sBIT_error_fn(png_structp pp, png_infop pi)
    png_set_sBIT(pp, pi, &bad);
 }
 
-static PNG_CONST struct
+static const struct
 {
    void          (*fn)(png_structp, png_infop);
-   PNG_CONST char *msg;
+   const char *msg;
    unsigned int    warning :1; /* the error is a warning... */
 } error_test[] =
     {
-       /* no warnings makes these errors undetectable. */
-       { sBIT0_error_fn, "sBIT(0): failed to detect error", 1 },
-       { sBIT_error_fn, "sBIT(too big): failed to detect error", 1 },
+       /* no warnings makes these errors undetectable prior to 1.7.0 */
+       { sBIT0_error_fn, "sBIT(0): failed to detect error",
+         PNG_LIBPNG_VER < 10700 },
+
+       { sBIT_error_fn, "sBIT(too big): failed to detect error", 
+         PNG_LIBPNG_VER < 10700 },
     };
 
 static void
-make_error(png_store* volatile psIn, png_byte PNG_CONST colour_type,
+make_error(png_store* const ps, png_byte const colour_type,
     png_byte bit_depth, int interlace_type, int test, png_const_charp name)
 {
-   png_store * volatile ps = psIn;
-
    context(ps, fault);
 
    check_interlace_type(interlace_type);
 
    Try
    {
-      volatile png_structp pp;
       png_infop pi;
-
-      pp = set_store_for_write(ps, &pi, name);
+      const png_structp pp = set_store_for_write(ps, &pi, name);
+      gnu_volatile(pp)
 
       if (pp == NULL)
          Throw ps;
@@ -4122,6 +4166,8 @@ make_error(png_store* volatile psIn, png_byte PNG_CONST colour_type,
 #     define exception__env exception_env_1
       Try
       {
+         gnu_volatile(exception__prev)
+
          /* Expect this to throw: */
          ps->expect_error = !error_test[test].warning;
          ps->expect_warning = error_test[test].warning;
@@ -4142,7 +4188,8 @@ make_error(png_store* volatile psIn, png_byte PNG_CONST colour_type,
       }
 
       Catch (fault)
-         ps = fault; /* expected exit, make sure ps is not clobbered */
+      { /* expected exit */
+      }
 #undef exception__prev
 #undef exception__env
 
@@ -4160,7 +4207,7 @@ make_error(png_store* volatile psIn, png_byte PNG_CONST colour_type,
       else
       {
          png_uint_32 h = transform_height(pp, colour_type, bit_depth);
-         int npasses = png_set_interlace_handling(pp);
+         int npasses = set_write_interlace_handling(pp, interlace_type);
          int pass;
 
          if (npasses != npasses_from_interlace_type(pp, interlace_type))
@@ -4193,8 +4240,8 @@ make_error(png_store* volatile psIn, png_byte PNG_CONST colour_type,
 }
 
 static int
-make_errors(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
-    int bdlo, int PNG_CONST bdhi)
+make_errors(png_modifier* const pm, png_byte const colour_type,
+    int bdlo, int const bdhi)
 {
    for (; bdlo <= bdhi; ++bdlo)
    {
@@ -4254,7 +4301,7 @@ perform_error_test(png_modifier *pm)
  * then the warning messages the library outputs will probably be garbage.
  */
 static void
-perform_formatting_test(png_store *volatile ps)
+perform_formatting_test(png_store *ps)
 {
 #ifdef PNG_TIME_RFC1123_SUPPORTED
    /* The handle into the formatting code is the RFC1123 support; this test does
@@ -4814,7 +4861,7 @@ static void PNGCBAPI
 progressive_row(png_structp ppIn, png_bytep new_row, png_uint_32 y, int pass)
 {
    png_const_structp pp = ppIn;
-   PNG_CONST standard_display *dp = voidcast(standard_display*,
+   const standard_display *dp = voidcast(standard_display*,
       png_get_progressive_ptr(pp));
 
    /* When handling interlacing some rows will be absent in each pass, the
@@ -4849,38 +4896,38 @@ progressive_row(png_structp ppIn, png_bytep new_row, png_uint_32 y, int pass)
 
       row = store_image_row(dp->ps, pp, 0, y);
 
-#ifdef PNG_READ_INTERLACING_SUPPORTED
       /* Combine the new row into the old: */
+#ifdef PNG_READ_DEINTERLACE_SUPPORTED
       if (dp->do_interlace)
+#endif
       {
          if (dp->interlace_type == PNG_INTERLACE_ADAM7)
             deinterlace_row(row, new_row, dp->pixel_size, dp->w, pass);
          else
             row_copy(row, new_row, dp->pixel_size * dp->w);
       }
+#ifdef PNG_READ_DEINTERLACE_SUPPORTED
       else
          png_progressive_combine_row(pp, row, new_row);
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
+#endif /* PNG_READ_DEINTERLACE_SUPPORTED */
    }
 
-#ifdef PNG_READ_INTERLACING_SUPPORTED
    else if (dp->interlace_type == PNG_INTERLACE_ADAM7 &&
        PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
        PNG_PASS_COLS(dp->w, pass) > 0)
       png_error(pp, "missing row in progressive de-interlacing");
-#endif /* PNG_READ_INTERLACING_SUPPORTED */
 }
 
 static void
 sequential_row(standard_display *dp, png_structp pp, png_infop pi,
-    PNG_CONST int iImage, PNG_CONST int iDisplay)
+    const int iImage, const int iDisplay)
 {
-   PNG_CONST int         npasses = dp->npasses;
-   PNG_CONST int         do_interlace = dp->do_interlace &&
+   const int         npasses = dp->npasses;
+   const int         do_interlace = dp->do_interlace &&
       dp->interlace_type == PNG_INTERLACE_ADAM7;
-   PNG_CONST png_uint_32 height = standard_height(pp, dp->id);
-   PNG_CONST png_uint_32 width = standard_width(pp, dp->id);
-   PNG_CONST png_store*  ps = dp->ps;
+   const png_uint_32 height = standard_height(pp, dp->id);
+   const png_uint_32 width = standard_width(pp, dp->id);
+   const png_store*  ps = dp->ps;
    int pass;
 
    for (pass=0; pass<npasses; ++pass)
@@ -5066,14 +5113,6 @@ standard_row_validate(standard_display *dp, png_const_structp pp,
     * In earlier passes 'row' will be partially filled in, with only the pixels
     * that have been read so far, but 'display' will have those pixels
     * replicated to fill the unread pixels while reading an interlaced image.
-#if PNG_LIBPNG_VER < 10506
-    * The side effect inside the libpng sequential reader is that the 'row'
-    * array retains the correct values for unwritten pixels within the row
-    * bytes, while the 'display' array gets bits off the end of the image (in
-    * the last byte) trashed.  Unfortunately in the progressive reader the
-    * row bytes are always trashed, so we always do a pixel_cmp here even though
-    * a memcmp of all cbRow bytes will succeed for the sequential reader.
-#endif
     */
    if (iImage >= 0 &&
       (where = pixel_cmp(std, store_image_row(dp->ps, pp, iImage, y),
@@ -5086,13 +5125,6 @@ standard_row_validate(standard_display *dp, png_const_structp pp,
       png_error(pp, msg);
    }
 
-#if PNG_LIBPNG_VER < 10506
-   /* In this case use pixel_cmp because we need to compare a partial
-    * byte at the end of the row if the row is not an exact multiple
-    * of 8 bits wide.  (This is fixed in libpng-1.5.6 and pixel_cmp is
-    * changed to match!)
-    */
-#endif
    if (iDisplay >= 0 &&
       (where = pixel_cmp(std, store_image_row(dp->ps, pp, iDisplay, y),
          dp->bit_width)) != 0)
@@ -5143,7 +5175,7 @@ standard_end(png_structp ppIn, png_infop pi)
 
 /* A single test run checking the standard image to ensure it is not damaged. */
 static void
-standard_test(png_store* PNG_CONST psIn, png_uint_32 PNG_CONST id,
+standard_test(png_store* const psIn, png_uint_32 const id,
    int do_interlace, int use_update_info)
 {
    standard_display d;
@@ -5231,8 +5263,8 @@ standard_test(png_store* PNG_CONST psIn, png_uint_32 PNG_CONST id,
 }
 
 static int
-test_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
-    int bdlo, int PNG_CONST bdhi)
+test_standard(png_modifier* const pm, png_byte const colour_type,
+    int bdlo, int const bdhi)
 {
    for (; bdlo <= bdhi; ++bdlo)
    {
@@ -5277,8 +5309,8 @@ perform_standard_test(png_modifier *pm)
 
 /********************************** SIZE TESTS ********************************/
 static int
-test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
-    int bdlo, int PNG_CONST bdhi)
+test_size(png_modifier* const pm, png_byte const colour_type,
+    int bdlo, int const bdhi)
 {
    /* Run the tests on each combination.
     *
@@ -5287,8 +5319,10 @@ test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
     * width and height.  This is a waste of time in practice, hence the
     * hinc and winc stuff:
     */
-   static PNG_CONST png_byte hinc[] = {1, 3, 11, 1, 5};
-   static PNG_CONST png_byte winc[] = {1, 9, 5, 7, 1};
+   static const png_byte hinc[] = {1, 3, 11, 1, 5};
+   static const png_byte winc[] = {1, 9, 5, 7, 1};
+   const int save_bdlo = bdlo;
+
    for (; bdlo <= bdhi; ++bdlo)
    {
       png_uint_32 h, w;
@@ -5314,22 +5348,6 @@ test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
          if (fail(pm))
             return 0;
 
-#     ifdef PNG_WRITE_INTERLACING_SUPPORTED
-         standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
-            PNG_INTERLACE_ADAM7, w, h, 0), 0/*do_interlace*/,
-            pm->use_update_info);
-
-         if (fail(pm))
-            return 0;
-
-         standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
-            PNG_INTERLACE_ADAM7, w, h, 1), 0/*do_interlace*/,
-            pm->use_update_info);
-
-         if (fail(pm))
-            return 0;
-#     endif
-
          /* Now validate the interlaced read side - do_interlace true,
           * in the progressive case this does actually make a difference
           * to the code used in the non-interlaced case too.
@@ -5341,7 +5359,45 @@ test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
          if (fail(pm))
             return 0;
 
+#     if CAN_WRITE_INTERLACE
+         /* Validate the pngvalid code itself: */
+         standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+            PNG_INTERLACE_ADAM7, w, h, 1), 1/*do_interlace*/,
+            pm->use_update_info);
+
+         if (fail(pm))
+            return 0;
+#     endif
+      }
+   }
+
+   /* Now do the tests of libpng interlace handling, after we have made sure
+    * that the pngvalid version works:
+    */
+   for (bdlo = save_bdlo; bdlo <= bdhi; ++bdlo)
+   {
+      png_uint_32 h, w;
+
+      for (h=1; h<=16; h+=hinc[bdlo]) for (w=1; w<=16; w+=winc[bdlo])
+      {
+#     ifdef PNG_READ_DEINTERLACE_SUPPORTED
+         /* Test with pngvalid generated interlaced images first; we have
+          * already verify these are ok (unless pngvalid has self-consistent
+          * read/write errors, which is unlikely), so this detects errors in the
+          * read side first:
+          */
+#     if CAN_WRITE_INTERLACE
+         standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+            PNG_INTERLACE_ADAM7, w, h, 1), 0/*do_interlace*/,
+            pm->use_update_info);
+
+         if (fail(pm))
+            return 0;
+#     endif
+#     endif /* READ_DEINTERLACE */
+
 #     ifdef PNG_WRITE_INTERLACING_SUPPORTED
+         /* Test the libpng write side against the pngvalid read side: */
          standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
             PNG_INTERLACE_ADAM7, w, h, 0), 1/*do_interlace*/,
             pm->use_update_info);
@@ -5349,6 +5405,18 @@ test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
          if (fail(pm))
             return 0;
 #     endif
+
+#     ifdef PNG_READ_DEINTERLACE_SUPPORTED
+#     ifdef PNG_WRITE_INTERLACING_SUPPORTED
+         /* Test both together: */
+         standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+            PNG_INTERLACE_ADAM7, w, h, 0), 0/*do_interlace*/,
+            pm->use_update_info);
+
+         if (fail(pm))
+            return 0;
+#     endif
+#     endif /* READ_DEINTERLACE */
       }
    }
 
@@ -5459,14 +5527,14 @@ image_pixel_setf(image_pixel *this, unsigned int rMax, unsigned int gMax,
 static void
 image_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type,
     png_byte bit_depth, png_uint_32 x, store_palette palette,
-    PNG_CONST image_pixel *format /*from pngvalid transform of input*/)
+    const image_pixel *format /*from pngvalid transform of input*/)
 {
-   PNG_CONST png_byte sample_depth = (png_byte)(colour_type ==
+   const png_byte sample_depth = (png_byte)(colour_type ==
       PNG_COLOR_TYPE_PALETTE ? 8 : bit_depth);
-   PNG_CONST unsigned int max = (1U<<sample_depth)-1;
-   PNG_CONST int swap16 = (format != 0 && format->swap16);
-   PNG_CONST int littleendian = (format != 0 && format->littleendian);
-   PNG_CONST int sig_bits = (format != 0 && format->sig_bits);
+   const unsigned int max = (1U<<sample_depth)-1;
+   const int swap16 = (format != 0 && format->swap16);
+   const int littleendian = (format != 0 && format->littleendian);
+   const int sig_bits = (format != 0 && format->sig_bits);
 
    /* Initially just set everything to the same number and the alpha to opaque.
     * Note that this currently assumes a simple palette where entry x has colour
@@ -5484,7 +5552,7 @@ image_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type,
       /* This permits the caller to default to the sample value. */
       if (palette != 0)
       {
-         PNG_CONST unsigned int i = this->palette_index;
+         const unsigned int i = this->palette_index;
 
          this->red = palette[i].red;
          this->green = palette[i].green;
@@ -5560,6 +5628,9 @@ image_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type,
    this->sig_bits = 0;
 }
 
+#if defined PNG_READ_EXPAND_SUPPORTED || defined PNG_READ_GRAY_TO_RGB_SUPPORTED\
+   || defined PNG_READ_EXPAND_SUPPORTED || defined PNG_READ_EXPAND_16_SUPPORTED\
+   || defined PNG_READ_BACKGROUND_SUPPORTED
 /* Convert a palette image to an rgb image.  This necessarily converts the tRNS
  * chunk at the same time, because the tRNS will be in palette form.  The way
  * palette validation works means that the original palette is never updated,
@@ -5589,10 +5660,14 @@ image_pixel_convert_PLTE(image_pixel *this)
 
 /* Add an alpha channel; this will import the tRNS information because tRNS is
  * not valid in an alpha image.  The bit depth will invariably be set to at
- * least 8.  Palette images will be converted to alpha (using the above API).
+ * least 8 prior to 1.7.0.  Palette images will be converted to alpha (using
+ * the above API).  With png_set_background the alpha channel is never expanded
+ * but this routine is used by pngvalid to simplify code; 'for_background'
+ * records this.
  */
 static void
-image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
+image_pixel_add_alpha(image_pixel *this, const standard_display *display,
+   int for_background)
 {
    if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
       image_pixel_convert_PLTE(this);
@@ -5601,11 +5676,21 @@ image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
    {
       if (this->colour_type == PNG_COLOR_TYPE_GRAY)
       {
-         if (this->bit_depth < 8)
-            this->bit_depth = this->sample_depth = 8;
+#        if PNG_LIBPNG_VER < 10700
+            if (!for_background && this->bit_depth < 8)
+               this->bit_depth = this->sample_depth = 8;
+#        endif
 
          if (this->have_tRNS)
          {
+            /* After 1.7 the expansion of bit depth only happens if there is a
+             * tRNS chunk to expand at this point.
+             */
+#           if PNG_LIBPNG_VER >= 10700
+               if (!for_background && this->bit_depth < 8)
+                  this->bit_depth = this->sample_depth = 8;
+#           endif
+
             this->have_tRNS = 0;
 
             /* Check the input, original, channel value here against the
@@ -5651,18 +5736,19 @@ image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
       this->alpha_sBIT = display->alpha_sBIT;
    }
 }
+#endif /* transforms that need image_pixel_add_alpha */
 
 struct transform_display;
 typedef struct image_transform
 {
    /* The name of this transform: a string. */
-   PNG_CONST char *name;
+   const char *name;
 
    /* Each transform can be disabled from the command line: */
    int enable;
 
    /* The global list of transforms; read only. */
-   struct image_transform *PNG_CONST list;
+   struct image_transform *const list;
 
    /* The global count of the number of times this transform has been set on an
     * image.
@@ -5675,7 +5761,7 @@ typedef struct image_transform
    /* The next transform in the list, each transform must call its own next
     * transform after it has processed the pixel successfully.
     */
-   PNG_CONST struct image_transform *next;
+   const struct image_transform *next;
 
    /* A single transform for the image, expressed as a series of function
     * callbacks and some space for values.
@@ -5683,12 +5769,12 @@ typedef struct image_transform
     * First a callback to add any required modifications to the png_modifier;
     * this gets called just before the modifier is set up for read.
     */
-   void (*ini)(PNG_CONST struct image_transform *this,
+   void (*ini)(const struct image_transform *this,
       struct transform_display *that);
 
    /* And a callback to set the transform on the current png_read_struct:
     */
-   void (*set)(PNG_CONST struct image_transform *this,
+   void (*set)(const struct image_transform *this,
       struct transform_display *that, png_structp pp, png_infop pi);
 
    /* Then a transform that takes an input pixel in one PNG format or another
@@ -5697,8 +5783,8 @@ typedef struct image_transform
     * in the libpng implementation!)  The png_structp is solely to allow error
     * reporting via png_error and png_warning.
     */
-   void (*mod)(PNG_CONST struct image_transform *this, image_pixel *that,
-      png_const_structp pp, PNG_CONST struct transform_display *display);
+   void (*mod)(const struct image_transform *this, image_pixel *that,
+      png_const_structp pp, const struct transform_display *display);
 
    /* Add this transform to the list and return true if the transform is
     * meaningful for this colour type and bit depth - if false then the
@@ -5706,7 +5792,7 @@ typedef struct image_transform
     * point running it.
     */
    int (*add)(struct image_transform *this,
-      PNG_CONST struct image_transform **that, png_byte colour_type,
+      const struct image_transform **that, png_byte colour_type,
       png_byte bit_depth);
 } image_transform;
 
@@ -5716,7 +5802,7 @@ typedef struct transform_display
 
    /* Parameters */
    png_modifier*              pm;
-   PNG_CONST image_transform* transform_list;
+   const image_transform* transform_list;
 
    /* Local variables */
    png_byte output_colour_type;
@@ -5758,7 +5844,7 @@ transform_set_encoding(transform_display *this)
 
 /* Three functions to end the list: */
 static void
-image_transform_ini_end(PNG_CONST image_transform *this,
+image_transform_ini_end(const image_transform *this,
    transform_display *that)
 {
    UNUSED(this)
@@ -5766,7 +5852,7 @@ image_transform_ini_end(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_set_end(PNG_CONST image_transform *this,
+image_transform_set_end(const image_transform *this,
    transform_display *that, png_structp pp, png_infop pi)
 {
    UNUSED(this)
@@ -5793,11 +5879,11 @@ sample_scale(double sample_value, unsigned int scale)
 }
 
 static void
-image_transform_mod_end(PNG_CONST image_transform *this, image_pixel *that,
-    png_const_structp pp, PNG_CONST transform_display *display)
+image_transform_mod_end(const image_transform *this, image_pixel *that,
+    png_const_structp pp, const transform_display *display)
 {
-   PNG_CONST unsigned int scale = (1U<<that->sample_depth)-1;
-   PNG_CONST int sig_bits = that->sig_bits;
+   const unsigned int scale = (1U<<that->sample_depth)-1;
+   const int sig_bits = that->sig_bits;
 
    UNUSED(this)
    UNUSED(pp)
@@ -5888,7 +5974,7 @@ static image_transform image_transform_end =
  */
 static void
 transform_display_init(transform_display *dp, png_modifier *pm, png_uint_32 id,
-    PNG_CONST image_transform *transform_list)
+    const image_transform *transform_list)
 {
    memset(dp, 0, sizeof *dp);
 
@@ -6072,7 +6158,7 @@ static void
 transform_range_check(png_const_structp pp, unsigned int r, unsigned int g,
    unsigned int b, unsigned int a, unsigned int in_digitized, double in,
    unsigned int out, png_byte sample_depth, double err, double limit,
-   PNG_CONST char *name, double digitization_error)
+   const char *name, double digitization_error)
 {
    /* Compare the scaled, digitzed, values of our local calculation (in+-err)
     * with the digitized values libpng produced;  'sample_depth' is the actual
@@ -6116,20 +6202,20 @@ transform_image_validate(transform_display *dp, png_const_structp pp,
    png_infop pi)
 {
    /* Constants for the loop below: */
-   PNG_CONST png_store* PNG_CONST ps = dp->this.ps;
-   PNG_CONST png_byte in_ct = dp->this.colour_type;
-   PNG_CONST png_byte in_bd = dp->this.bit_depth;
-   PNG_CONST png_uint_32 w = dp->this.w;
-   PNG_CONST png_uint_32 h = dp->this.h;
-   PNG_CONST png_byte out_ct = dp->output_colour_type;
-   PNG_CONST png_byte out_bd = dp->output_bit_depth;
-   PNG_CONST png_byte sample_depth = (png_byte)(out_ct ==
+   const png_store* const ps = dp->this.ps;
+   const png_byte in_ct = dp->this.colour_type;
+   const png_byte in_bd = dp->this.bit_depth;
+   const png_uint_32 w = dp->this.w;
+   const png_uint_32 h = dp->this.h;
+   const png_byte out_ct = dp->output_colour_type;
+   const png_byte out_bd = dp->output_bit_depth;
+   const png_byte sample_depth = (png_byte)(out_ct ==
       PNG_COLOR_TYPE_PALETTE ? 8 : out_bd);
-   PNG_CONST png_byte red_sBIT = dp->this.red_sBIT;
-   PNG_CONST png_byte green_sBIT = dp->this.green_sBIT;
-   PNG_CONST png_byte blue_sBIT = dp->this.blue_sBIT;
-   PNG_CONST png_byte alpha_sBIT = dp->this.alpha_sBIT;
-   PNG_CONST int have_tRNS = dp->this.is_transparent;
+   const png_byte red_sBIT = dp->this.red_sBIT;
+   const png_byte green_sBIT = dp->this.green_sBIT;
+   const png_byte blue_sBIT = dp->this.blue_sBIT;
+   const png_byte alpha_sBIT = dp->this.alpha_sBIT;
+   const int have_tRNS = dp->this.is_transparent;
    double digitization_error;
 
    store_palette out_palette;
@@ -6184,7 +6270,7 @@ transform_image_validate(transform_display *dp, png_const_structp pp,
 
    for (y=0; y<h; ++y)
    {
-      png_const_bytep PNG_CONST pRow = store_image_row(ps, pp, 0, y);
+      png_const_bytep const pRow = store_image_row(ps, pp, 0, y);
       png_uint_32 x;
 
       /* The original, standard, row pre-transforms. */
@@ -6216,7 +6302,7 @@ transform_image_validate(transform_display *dp, png_const_structp pp,
          b = in_pixel.blue;
          a = in_pixel.alpha;
 
-         /* This applies the transforms to the input date, including output
+         /* This applies the transforms to the input data, including output
           * format operations which must be used when reading the output
           * pixel that libpng produces.
           */
@@ -6290,8 +6376,8 @@ transform_end(png_structp ppIn, png_infop pi)
 
 /* A single test run. */
 static void
-transform_test(png_modifier *pmIn, PNG_CONST png_uint_32 idIn,
-    PNG_CONST image_transform* transform_listIn, PNG_CONST char * volatile name)
+transform_test(png_modifier *pmIn, const png_uint_32 idIn,
+    const image_transform* transform_listIn, const char * const name)
 {
    transform_display d;
    context(&pmIn->this, fault);
@@ -6392,8 +6478,11 @@ static image_transform ITSTRUCT(name) =\
 #define PT ITSTRUCT(end) /* stores the previous transform */
 
 /* To save code: */
-static void
-image_transform_default_ini(PNG_CONST image_transform *this,
+extern void image_transform_default_ini(const image_transform *this,
+   transform_display *that); /* silence GCC warnings */
+
+void /* private, but almost always needed */
+image_transform_default_ini(const image_transform *this,
     transform_display *that)
 {
    this->next->ini(this->next, that);
@@ -6402,7 +6491,7 @@ image_transform_default_ini(PNG_CONST image_transform *this,
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
 static int
 image_transform_default_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
    UNUSED(bit_depth)
@@ -6417,7 +6506,7 @@ image_transform_default_add(image_transform *this,
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* png_set_palette_to_rgb */
 static void
-image_transform_png_set_palette_to_rgb_set(PNG_CONST image_transform *this,
+image_transform_png_set_palette_to_rgb_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_palette_to_rgb(pp);
@@ -6425,9 +6514,9 @@ image_transform_png_set_palette_to_rgb_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_palette_to_rgb_mod(PNG_CONST image_transform *this,
+image_transform_png_set_palette_to_rgb_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
       image_pixel_convert_PLTE(that);
@@ -6437,7 +6526,7 @@ image_transform_png_set_palette_to_rgb_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_palette_to_rgb_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -6455,7 +6544,7 @@ IT(palette_to_rgb);
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* png_set_tRNS_to_alpha */
 static void
-image_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this,
+image_transform_png_set_tRNS_to_alpha_set(const image_transform *this,
    transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_tRNS_to_alpha(pp);
@@ -6470,20 +6559,27 @@ image_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_tRNS_to_alpha_mod(PNG_CONST image_transform *this,
+image_transform_png_set_tRNS_to_alpha_mod(const image_transform *this,
    image_pixel *that, png_const_structp pp,
-   PNG_CONST transform_display *display)
+   const transform_display *display)
 {
+#if PNG_LIBPNG_VER < 10700
    /* LIBPNG BUG: this always forces palette images to RGB. */
    if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
       image_pixel_convert_PLTE(that);
+#endif
 
    /* This effectively does an 'expand' only if there is some transparency to
     * convert to an alpha channel.
     */
    if (that->have_tRNS)
-      image_pixel_add_alpha(that, &display->this);
+#     if PNG_LIBPNG_VER >= 10700
+         if (that->colour_type != PNG_COLOR_TYPE_PALETTE &&
+             (that->colour_type & PNG_COLOR_MASK_ALPHA) == 0)
+#     endif
+      image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
 
+#if PNG_LIBPNG_VER < 10700
    /* LIBPNG BUG: otherwise libpng still expands to 8 bits! */
    else
    {
@@ -6492,13 +6588,14 @@ image_transform_png_set_tRNS_to_alpha_mod(PNG_CONST image_transform *this,
       if (that->sample_depth < 8)
          that->sample_depth = 8;
    }
+#endif
 
    this->next->mod(this->next, that, pp, display);
 }
 
 static int
 image_transform_png_set_tRNS_to_alpha_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -6507,9 +6604,14 @@ image_transform_png_set_tRNS_to_alpha_add(image_transform *this,
 
    /* We don't know yet whether there will be a tRNS chunk, but we know that
     * this transformation should do nothing if there already is an alpha
-    * channel.
+    * channel.  In addition, after the bug fix in 1.7.0, there is no longer
+    * any action on a palette image.
     */
-   return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
+   return
+#  if PNG_LIBPNG_VER >= 10700
+      colour_type != PNG_COLOR_TYPE_PALETTE &&
+#  endif
+   (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
 }
 
 IT(tRNS_to_alpha);
@@ -6520,7 +6622,7 @@ IT(tRNS_to_alpha);
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* png_set_gray_to_rgb */
 static void
-image_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this,
+image_transform_png_set_gray_to_rgb_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_gray_to_rgb(pp);
@@ -6529,9 +6631,9 @@ image_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_gray_to_rgb_mod(PNG_CONST image_transform *this,
+image_transform_png_set_gray_to_rgb_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    /* NOTE: we can actually pend the tRNS processing at this point because we
     * can correctly recognize the original pixel value even though we have
@@ -6539,7 +6641,7 @@ image_transform_png_set_gray_to_rgb_mod(PNG_CONST image_transform *this,
     * doesn't do this, so we don't either.
     */
    if ((that->colour_type & PNG_COLOR_MASK_COLOR) == 0 && that->have_tRNS)
-      image_pixel_add_alpha(that, &display->this);
+      image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
 
    /* Simply expand the bit depth and alter the colour type as required. */
    if (that->colour_type == PNG_COLOR_TYPE_GRAY)
@@ -6562,7 +6664,7 @@ image_transform_png_set_gray_to_rgb_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_gray_to_rgb_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -6580,7 +6682,7 @@ IT(gray_to_rgb);
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* png_set_expand */
 static void
-image_transform_png_set_expand_set(PNG_CONST image_transform *this,
+image_transform_png_set_expand_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_expand(pp);
@@ -6592,9 +6694,9 @@ image_transform_png_set_expand_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_expand_mod(PNG_CONST image_transform *this,
+image_transform_png_set_expand_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    /* The general expand case depends on what the colour type is: */
    if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
@@ -6603,14 +6705,14 @@ image_transform_png_set_expand_mod(PNG_CONST image_transform *this,
       that->sample_depth = that->bit_depth = 8;
 
    if (that->have_tRNS)
-      image_pixel_add_alpha(that, &display->this);
+      image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
 
    this->next->mod(this->next, that, pp, display);
 }
 
 static int
 image_transform_png_set_expand_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -6630,11 +6732,11 @@ IT(expand);
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* png_set_expand_gray_1_2_4_to_8
- * LIBPNG BUG: this just does an 'expand'
+ * Pre 1.7.0 LIBPNG BUG: this just does an 'expand'
  */
 static void
 image_transform_png_set_expand_gray_1_2_4_to_8_set(
-    PNG_CONST image_transform *this, transform_display *that, png_structp pp,
+    const image_transform *this, transform_display *that, png_structp pp,
     png_infop pi)
 {
    png_set_expand_gray_1_2_4_to_8(pp);
@@ -6644,18 +6746,39 @@ image_transform_png_set_expand_gray_1_2_4_to_8_set(
 
 static void
 image_transform_png_set_expand_gray_1_2_4_to_8_mod(
-    PNG_CONST image_transform *this, image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const image_transform *this, image_pixel *that, png_const_structp pp,
+    const transform_display *display)
 {
+#if PNG_LIBPNG_VER < 10700
    image_transform_png_set_expand_mod(this, that, pp, display);
+#else
+   /* Only expand grayscale of bit depth less than 8: */
+   if (that->colour_type == PNG_COLOR_TYPE_GRAY &&
+       that->bit_depth < 8)
+      that->sample_depth = that->bit_depth = 8;
+
+   this->next->mod(this->next, that, pp, display);
+#endif /* 1.7 or later */
 }
 
 static int
 image_transform_png_set_expand_gray_1_2_4_to_8_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
+#if PNG_LIBPNG_VER < 10700
    return image_transform_png_set_expand_add(this, that, colour_type,
       bit_depth);
+#else
+   UNUSED(bit_depth)
+
+   this->next = *that;
+   *that = this;
+
+   /* This should do nothing unless the color type is gray and the bit depth is
+    * less than 8:
+    */
+   return colour_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8;
+#endif /* 1.7 or later */
 }
 
 IT(expand_gray_1_2_4_to_8);
@@ -6666,22 +6789,24 @@ IT(expand_gray_1_2_4_to_8);
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
 /* png_set_expand_16 */
 static void
-image_transform_png_set_expand_16_set(PNG_CONST image_transform *this,
+image_transform_png_set_expand_16_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_expand_16(pp);
 
-   /* NOTE: at present libpng does SET_EXPAND as well, so tRNS is expanded. */
-   if (that->this.has_tRNS)
-      that->this.is_transparent = 1;
+   /* NOTE: prior to 1.7 libpng does SET_EXPAND as well, so tRNS is expanded. */
+#  if PNG_LIBPNG_VER < 10700
+      if (that->this.has_tRNS)
+         that->this.is_transparent = 1;
+#  endif
 
    this->next->set(this->next, that, pp, pi);
 }
 
 static void
-image_transform_png_set_expand_16_mod(PNG_CONST image_transform *this,
+image_transform_png_set_expand_16_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    /* Expect expand_16 to expand everything to 16 bits as a result of also
     * causing 'expand' to happen.
@@ -6690,7 +6815,7 @@ image_transform_png_set_expand_16_mod(PNG_CONST image_transform *this,
       image_pixel_convert_PLTE(that);
 
    if (that->have_tRNS)
-      image_pixel_add_alpha(that, &display->this);
+      image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
 
    if (that->bit_depth < 16)
       that->sample_depth = that->bit_depth = 16;
@@ -6700,7 +6825,7 @@ image_transform_png_set_expand_16_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_expand_16_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
 
@@ -6719,7 +6844,7 @@ IT(expand_16);
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED  /* API added in 1.5.4 */
 /* png_set_scale_16 */
 static void
-image_transform_png_set_scale_16_set(PNG_CONST image_transform *this,
+image_transform_png_set_scale_16_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_scale_16(pp);
@@ -6727,9 +6852,9 @@ image_transform_png_set_scale_16_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_scale_16_mod(PNG_CONST image_transform *this,
+image_transform_png_set_scale_16_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->bit_depth == 16)
    {
@@ -6745,7 +6870,7 @@ image_transform_png_set_scale_16_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_scale_16_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
 
@@ -6763,7 +6888,7 @@ IT(scale_16);
 #ifdef PNG_READ_16_TO_8_SUPPORTED /* the default before 1.5.4 */
 /* png_set_strip_16 */
 static void
-image_transform_png_set_strip_16_set(PNG_CONST image_transform *this,
+image_transform_png_set_strip_16_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_strip_16(pp);
@@ -6771,9 +6896,9 @@ image_transform_png_set_strip_16_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_strip_16_mod(PNG_CONST image_transform *this,
+image_transform_png_set_strip_16_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->bit_depth == 16)
    {
@@ -6798,7 +6923,7 @@ image_transform_png_set_strip_16_mod(PNG_CONST image_transform *this,
           * png_set_scale_16 API in 1.5.4 (but 1.5.4+ always defines the above!)
           */
          {
-            PNG_CONST double d = (255-128.5)/65535;
+            const double d = (255-128.5)/65535;
             that->rede += d;
             that->greene += d;
             that->bluee += d;
@@ -6812,7 +6937,7 @@ image_transform_png_set_strip_16_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_strip_16_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
 
@@ -6830,7 +6955,7 @@ IT(strip_16);
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
 /* png_set_strip_alpha */
 static void
-image_transform_png_set_strip_alpha_set(PNG_CONST image_transform *this,
+image_transform_png_set_strip_alpha_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_strip_alpha(pp);
@@ -6838,9 +6963,9 @@ image_transform_png_set_strip_alpha_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_strip_alpha_mod(PNG_CONST image_transform *this,
+image_transform_png_set_strip_alpha_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
       that->colour_type = PNG_COLOR_TYPE_GRAY;
@@ -6855,7 +6980,7 @@ image_transform_png_set_strip_alpha_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_strip_alpha_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -6876,7 +7001,8 @@ IT(strip_alpha);
  *    png_fixed_point green)
  * png_get_rgb_to_gray_status
  *
- * The 'default' test here uses values known to be used inside libpng:
+ * The 'default' test here uses values known to be used inside libpng prior to
+ * 1.7.0:
  *
  *   red:    6968
  *   green: 23434
@@ -6913,11 +7039,11 @@ static struct
 #undef image_transform_ini
 #define image_transform_ini image_transform_png_set_rgb_to_gray_ini
 static void
-image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
+image_transform_png_set_rgb_to_gray_ini(const image_transform *this,
     transform_display *that)
 {
    png_modifier *pm = that->pm;
-   PNG_CONST color_encoding *e = pm->current_encoding;
+   const color_encoding *e = pm->current_encoding;
 
    UNUSED(this)
 
@@ -6932,7 +7058,7 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
       /* Coefficients come from the encoding, but may need to be normalized to a
        * white point Y of 1.0
        */
-      PNG_CONST double whiteY = e->red.Y + e->green.Y + e->blue.Y;
+      const double whiteY = e->red.Y + e->green.Y + e->blue.Y;
 
       data.red_coefficient = e->red.Y;
       data.green_coefficient = e->green.Y;
@@ -6949,9 +7075,15 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
    else
    {
       /* The default (built in) coeffcients, as above: */
-      data.red_coefficient = 6968 / 32768.;
-      data.green_coefficient = 23434 / 32768.;
-      data.blue_coefficient = 2366 / 32768.;
+#     if PNG_LIBPNG_VER < 10700
+         data.red_coefficient = 6968 / 32768.;
+         data.green_coefficient = 23434 / 32768.;
+         data.blue_coefficient = 2366 / 32768.;
+#     else
+         data.red_coefficient = .2126;
+         data.green_coefficient = .7152;
+         data.blue_coefficient = .0722;
+#     endif
    }
 
    data.gamma = pm->current_gamma;
@@ -7026,7 +7158,7 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
           *  conversion adds another +/-2 in the 16-bit case and
           *  +/-(1<<(15-PNG_MAX_GAMMA_8)) in the 8-bit case.
           */
-         that->pm->limit += pow(
+         that->pm->limit += (pow)(
 #           if PNG_MAX_GAMMA_8 < 14
                (that->this.bit_depth == 16 ? 8. :
                   6. + (1<<(15-PNG_MAX_GAMMA_8)))
@@ -7050,7 +7182,7 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
           * affects the limit used for checking for internal calculation errors,
           * not the actual limit imposed by pngvalid on the output errors.
           */
-         that->pm->limit += pow(
+         that->pm->limit += (pow)(
 #        if DIGITIZE
             1.3
 #        else
@@ -7071,10 +7203,10 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_rgb_to_gray_set(PNG_CONST image_transform *this,
+image_transform_png_set_rgb_to_gray_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
-   PNG_CONST int error_action = 1; /* no error, no defines in png.h */
+   const int error_action = 1; /* no error, no defines in png.h */
 
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
       png_set_rgb_to_gray(pp, error_action, data.red_to_set, data.green_to_set);
@@ -7111,7 +7243,7 @@ image_transform_png_set_rgb_to_gray_set(PNG_CONST image_transform *this,
                & PNG_INFO_cHRM) != 0)
          {
             double maxe;
-            PNG_CONST char *el;
+            const char *el;
             color_encoding e, o;
 
             /* Expect libpng to return a normalized result, but the original
@@ -7198,21 +7330,23 @@ image_transform_png_set_rgb_to_gray_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
+image_transform_png_set_rgb_to_gray_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if ((that->colour_type & PNG_COLOR_MASK_COLOR) != 0)
    {
       double gray, err;
 
-      if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
-         image_pixel_convert_PLTE(that);
+#     if PNG_LIBPNG_VER < 10700
+         if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
+            image_pixel_convert_PLTE(that);
+#     endif
 
       /* Image now has RGB channels... */
 #  if DIGITIZE
       {
-         PNG_CONST png_modifier *pm = display->pm;
+         const png_modifier *pm = display->pm;
          const unsigned int sample_depth = that->sample_depth;
          const unsigned int calc_depth = (pm->assume_16_bit_calculations ? 16 :
             sample_depth);
@@ -7262,8 +7396,8 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
 
          if (data.gamma != 1)
          {
-            PNG_CONST double power = 1/data.gamma;
-            PNG_CONST double abse = .5/(sample_depth == 16 ? 65535 : 255);
+            const double power = 1/data.gamma;
+            const double abse = .5/(sample_depth == 16 ? 65535 : 255);
 
             /* If a gamma calculation is done it is done using lookup tables of
              * precision gamma_depth, so the already digitized value above may
@@ -7307,8 +7441,8 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
             b * data.blue_coefficient;
 
          {
-            PNG_CONST int do_round = data.gamma != 1 || calc_depth == 16;
-            PNG_CONST double ce = 2. / 32768;
+            const int do_round = data.gamma != 1 || calc_depth == 16;
+            const double ce = 2. / 32768;
 
             graylo = DD(rlo * (data.red_coefficient-ce) +
                glo * (data.green_coefficient-ce) +
@@ -7326,7 +7460,7 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
          /* And invert the gamma. */
          if (data.gamma != 1)
          {
-            PNG_CONST double power = data.gamma;
+            const double power = data.gamma;
 
             /* And this happens yet again, shifting the values once more. */
             if (gamma_depth != sample_depth)
@@ -7384,16 +7518,21 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
          double b = that->bluef;
          double be = that->bluee;
 
-         /* The true gray case involves no math. */
-         if (r == g && r == b)
-         {
-            gray = r;
-            err = re;
-            if (err < ge) err = ge;
-            if (err < be) err = be;
-         }
+#        if PNG_LIBPNG_VER < 10700
+            /* The true gray case involves no math in earlier versions (not
+             * true, there was some if gamma correction was happening too.)
+             */
+            if (r == g && r == b)
+            {
+               gray = r;
+               err = re;
+               if (err < ge) err = ge;
+               if (err < be) err = be;
+            }
 
-         else if (data.gamma == 1)
+            else
+#        endif /* before 1.7 */
+         if (data.gamma == 1)
          {
             /* There is no need to do the conversions to and from linear space,
              * so the calculation should be a lot more accurate.  There is a
@@ -7429,7 +7568,7 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
              * lookups in the calculation and each introduces a quantization
              * error defined by the table size.
              */
-            PNG_CONST png_modifier *pm = display->pm;
+            const png_modifier *pm = display->pm;
             double in_qe = (that->sample_depth > 8 ? .5/65535 : .5/255);
             double out_qe = (that->sample_depth > 8 ? .5/65535 :
                (pm->assume_16_bit_calculations ? .5/(1<<PNG_MAX_GAMMA_8) :
@@ -7519,7 +7658,7 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_rgb_to_gray_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -7550,7 +7689,7 @@ IT(rgb_to_gray);
 static image_pixel data;
 
 static void
-image_transform_png_set_background_set(PNG_CONST image_transform *this,
+image_transform_png_set_background_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_byte colour_type, bit_depth;
@@ -7613,13 +7752,13 @@ image_transform_png_set_background_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_background_mod(PNG_CONST image_transform *this,
+image_transform_png_set_background_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    /* Check for tRNS first: */
    if (that->have_tRNS && that->colour_type != PNG_COLOR_TYPE_PALETTE)
-      image_pixel_add_alpha(that, &display->this);
+      image_pixel_add_alpha(that, &display->this, 1/*for background*/);
 
    /* This is only necessary if the alpha value is less than 1. */
    if (that->alphaf < 1)
@@ -7698,7 +7837,7 @@ IT(background);
  *  png_set_invert_alpha(png_structrp png_ptr)
  */
 static void
-image_transform_png_set_invert_alpha_set(PNG_CONST image_transform *this,
+image_transform_png_set_invert_alpha_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_invert_alpha(pp);
@@ -7706,9 +7845,9 @@ image_transform_png_set_invert_alpha_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_invert_alpha_mod(PNG_CONST image_transform *this,
+image_transform_png_set_invert_alpha_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->colour_type & 4)
       that->alpha_inverted = 1;
@@ -7718,7 +7857,7 @@ image_transform_png_set_invert_alpha_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_invert_alpha_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -7744,7 +7883,7 @@ IT(invert_alpha);
  * This only has an effect on RGB and RGBA pixels.
  */
 static void
-image_transform_png_set_bgr_set(PNG_CONST image_transform *this,
+image_transform_png_set_bgr_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_bgr(pp);
@@ -7752,9 +7891,9 @@ image_transform_png_set_bgr_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_bgr_mod(PNG_CONST image_transform *this,
+image_transform_png_set_bgr_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->colour_type == PNG_COLOR_TYPE_RGB ||
        that->colour_type == PNG_COLOR_TYPE_RGBA)
@@ -7765,7 +7904,7 @@ image_transform_png_set_bgr_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_bgr_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -7791,7 +7930,7 @@ IT(bgr);
  * This only has an effect on GA and RGBA pixels.
  */
 static void
-image_transform_png_set_swap_alpha_set(PNG_CONST image_transform *this,
+image_transform_png_set_swap_alpha_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_swap_alpha(pp);
@@ -7799,9 +7938,9 @@ image_transform_png_set_swap_alpha_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_swap_alpha_mod(PNG_CONST image_transform *this,
+image_transform_png_set_swap_alpha_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->colour_type == PNG_COLOR_TYPE_GA ||
        that->colour_type == PNG_COLOR_TYPE_RGBA)
@@ -7812,7 +7951,7 @@ image_transform_png_set_swap_alpha_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_swap_alpha_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -7836,7 +7975,7 @@ IT(swap_alpha);
  *  png_set_swap(png_structrp png_ptr)
  */
 static void
-image_transform_png_set_swap_set(PNG_CONST image_transform *this,
+image_transform_png_set_swap_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_swap(pp);
@@ -7844,9 +7983,9 @@ image_transform_png_set_swap_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_swap_mod(PNG_CONST image_transform *this,
+image_transform_png_set_swap_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->bit_depth == 16)
       that->swap16 = 1;
@@ -7856,7 +7995,7 @@ image_transform_png_set_swap_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_swap_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
 
@@ -7890,7 +8029,7 @@ static struct
 } data;
 
 static void
-image_transform_png_set_filler_set(PNG_CONST image_transform *this,
+image_transform_png_set_filler_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    /* Need a random choice for 'before' and 'after' as well as for the
@@ -7911,15 +8050,15 @@ image_transform_png_set_filler_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_filler_mod(PNG_CONST image_transform *this,
+image_transform_png_set_filler_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->bit_depth >= 8 &&
        (that->colour_type == PNG_COLOR_TYPE_RGB ||
         that->colour_type == PNG_COLOR_TYPE_GRAY))
    {
-      PNG_CONST unsigned int max = (1U << that->bit_depth)-1;
+      const unsigned int max = (1U << that->bit_depth)-1;
       that->alpha = data.filler & max;
       that->alphaf = ((double)that->alpha) / max;
       that->alphae = 0;
@@ -7939,7 +8078,7 @@ image_transform_png_set_filler_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_filler_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    this->next = *that;
    *that = this;
@@ -7963,7 +8102,7 @@ static struct
 } data;
 
 static void
-image_transform_png_set_add_alpha_set(PNG_CONST image_transform *this,
+image_transform_png_set_add_alpha_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    /* Need a random choice for 'before' and 'after' as well as for the
@@ -7978,15 +8117,15 @@ image_transform_png_set_add_alpha_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_add_alpha_mod(PNG_CONST image_transform *this,
+image_transform_png_set_add_alpha_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->bit_depth >= 8 &&
        (that->colour_type == PNG_COLOR_TYPE_RGB ||
         that->colour_type == PNG_COLOR_TYPE_GRAY))
    {
-      PNG_CONST unsigned int max = (1U << that->bit_depth)-1;
+      const unsigned int max = (1U << that->bit_depth)-1;
       that->alpha = data.filler & max;
       that->alphaf = ((double)that->alpha) / max;
       that->alphae = 0;
@@ -8000,7 +8139,7 @@ image_transform_png_set_add_alpha_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_add_alpha_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    this->next = *that;
    *that = this;
@@ -8026,7 +8165,7 @@ IT(add_alpha);
  * per pixel.
  */
 static void
-image_transform_png_set_packing_set(PNG_CONST image_transform *this,
+image_transform_png_set_packing_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_packing(pp);
@@ -8035,9 +8174,9 @@ image_transform_png_set_packing_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_packing_mod(PNG_CONST image_transform *this,
+image_transform_png_set_packing_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    /* The general expand case depends on what the colour type is,
     * low bit-depth pixel values are unpacked into bytes without
@@ -8051,7 +8190,7 @@ image_transform_png_set_packing_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_packing_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
 
@@ -8076,7 +8215,7 @@ IT(packing);
  *  png_set_packswap(png_structrp png_ptr)
  */
 static void
-image_transform_png_set_packswap_set(PNG_CONST image_transform *this,
+image_transform_png_set_packswap_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_packswap(pp);
@@ -8084,9 +8223,9 @@ image_transform_png_set_packswap_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_packswap_mod(PNG_CONST image_transform *this,
+image_transform_png_set_packswap_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->bit_depth < 8)
       that->littleendian = 1;
@@ -8096,7 +8235,7 @@ image_transform_png_set_packswap_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_packswap_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(colour_type)
 
@@ -8120,7 +8259,7 @@ IT(packswap);
  *  png_set_invert_mono(png_structrp png_ptr)
  */
 static void
-image_transform_png_set_invert_mono_set(PNG_CONST image_transform *this,
+image_transform_png_set_invert_mono_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_invert_mono(pp);
@@ -8128,9 +8267,9 @@ image_transform_png_set_invert_mono_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_invert_mono_mod(PNG_CONST image_transform *this,
+image_transform_png_set_invert_mono_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    if (that->colour_type & 4)
       that->mono_inverted = 1;
@@ -8140,7 +8279,7 @@ image_transform_png_set_invert_mono_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_invert_mono_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -8167,7 +8306,7 @@ IT(invert_mono);
 static png_color_8 data;
 
 static void
-image_transform_png_set_shift_set(PNG_CONST image_transform *this,
+image_transform_png_set_shift_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    /* Get a random set of shifts.  The shifts need to do something
@@ -8176,7 +8315,7 @@ image_transform_png_set_shift_set(PNG_CONST image_transform *this,
     * field is randomized independently.  This acts as a check that
     * libpng does use the correct field.
     */
-   PNG_CONST unsigned int depth = that->this.bit_depth;
+   const unsigned int depth = that->this.bit_depth;
 
    data.red = (png_byte)/*SAFE*/(random_mod(depth)+1);
    data.green = (png_byte)/*SAFE*/(random_mod(depth)+1);
@@ -8189,9 +8328,9 @@ image_transform_png_set_shift_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_shift_mod(PNG_CONST image_transform *this,
+image_transform_png_set_shift_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    /* Copy the correct values into the sBIT fields, libpng does not do
     * anything to palette data:
@@ -8222,7 +8361,7 @@ image_transform_png_set_shift_mod(PNG_CONST image_transform *this,
 
 static int
 image_transform_png_set_shift_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    UNUSED(bit_depth)
 
@@ -8240,7 +8379,7 @@ IT(shift);
 
 #ifdef THIS_IS_THE_PROFORMA
 static void
-image_transform_png_set_@_set(PNG_CONST image_transform *this,
+image_transform_png_set_@_set(const image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_@(pp);
@@ -8248,16 +8387,16 @@ image_transform_png_set_@_set(PNG_CONST image_transform *this,
 }
 
 static void
-image_transform_png_set_@_mod(PNG_CONST image_transform *this,
+image_transform_png_set_@_mod(const image_transform *this,
     image_pixel *that, png_const_structp pp,
-    PNG_CONST transform_display *display)
+    const transform_display *display)
 {
    this->next->mod(this->next, that, pp, display);
 }
 
 static int
 image_transform_png_set_@_add(image_transform *this,
-    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+    const image_transform **that, png_byte colour_type, png_byte bit_depth)
 {
    this->next = *that;
    *that = this;
@@ -8270,10 +8409,10 @@ IT(@);
 
 
 /* This may just be 'end' if all the transforms are disabled! */
-static image_transform *PNG_CONST image_transform_first = &PT;
+static image_transform *const image_transform_first = &PT;
 
 static void
-transform_enable(PNG_CONST char *name)
+transform_enable(const char *name)
 {
    /* Everything starts out enabled, so if we see an 'enable' disabled
     * everything else the first time round.
@@ -8306,7 +8445,7 @@ transform_enable(PNG_CONST char *name)
 }
 
 static void
-transform_disable(PNG_CONST char *name)
+transform_disable(const char *name)
 {
    image_transform *list = image_transform_first;
 
@@ -8369,7 +8508,7 @@ image_transform_test_counter(png_uint_32 counter, unsigned int max)
 }
 
 static png_uint_32
-image_transform_add(PNG_CONST image_transform **this, unsigned int max,
+image_transform_add(const image_transform **this, unsigned int max,
    png_uint_32 counter, char *name, size_t sizeof_name, size_t *pos,
    png_byte colour_type, png_byte bit_depth)
 {
@@ -8465,7 +8604,7 @@ perform_transform_test(png_modifier *pm)
       for (;;)
       {
          size_t pos = base_pos;
-         PNG_CONST image_transform *list = 0;
+         const image_transform *list = 0;
 
          /* 'max' is currently hardwired to '1'; this should be settable on the
           * command line.
@@ -8526,7 +8665,7 @@ static void
 gamma_display_init(gamma_display *dp, png_modifier *pm, png_uint_32 id,
     double file_gamma, double screen_gamma, png_byte sbit, int threshold_test,
     int use_input_precision, int scale16, int expand16,
-    int do_background, PNG_CONST png_color_16 *pointer_to_the_background_color,
+    int do_background, const png_color_16 *pointer_to_the_background_color,
     double background_gamma)
 {
    /* Standard fields */
@@ -8594,9 +8733,9 @@ gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi)
           * non-inverted, represenation.  It provides a default for the PNG file
           * gamma, but since the file has a gAMA chunk this does not matter.
           */
-         PNG_CONST double sg = dp->screen_gamma;
+         const double sg = dp->screen_gamma;
 #        ifndef PNG_FLOATING_POINT_SUPPORTED
-            PNG_CONST png_fixed_point g = fix(sg);
+            const png_fixed_point g = fix(sg);
 #        endif
 
 #        ifdef PNG_FLOATING_POINT_SUPPORTED
@@ -8642,9 +8781,9 @@ gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi)
 #     ifdef PNG_READ_BACKGROUND_SUPPORTED
          /* NOTE: this assumes the caller provided the correct background gamma!
           */
-         PNG_CONST double bg = dp->background_gamma;
+         const double bg = dp->background_gamma;
 #        ifndef PNG_FLOATING_POINT_SUPPORTED
-            PNG_CONST png_fixed_point g = fix(bg);
+            const png_fixed_point g = fix(bg);
 #        endif
 
 #        ifdef PNG_FLOATING_POINT_SUPPORTED
@@ -8718,7 +8857,7 @@ static void
 init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
     int in_depth, int out_depth)
 {
-   PNG_CONST unsigned int outmax = (1U<<out_depth)-1;
+   const unsigned int outmax = (1U<<out_depth)-1;
 
    vi->pp = pp;
    vi->dp = dp;
@@ -8765,7 +8904,7 @@ init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
 
       if (vi->do_background != 0)
       {
-         PNG_CONST double bg_inverse = 1/dp->background_gamma;
+         const double bg_inverse = 1/dp->background_gamma;
          double r, g, b;
 
          /* Caller must at least put the gray value into the red channel */
@@ -8879,15 +9018,15 @@ gamma_component_compose(int do_background, double input_sample, double alpha,
 
 /* This API returns the encoded *input* component, in the range 0..1 */
 static double
-gamma_component_validate(PNG_CONST char *name, PNG_CONST validate_info *vi,
-    PNG_CONST unsigned int id, PNG_CONST unsigned int od,
-    PNG_CONST double alpha /* <0 for the alpha channel itself */,
-    PNG_CONST double background /* component background value */)
+gamma_component_validate(const char *name, const validate_info *vi,
+    const unsigned int id, const unsigned int od,
+    const double alpha /* <0 for the alpha channel itself */,
+    const double background /* component background value */)
 {
-   PNG_CONST unsigned int isbit = id >> vi->isbit_shift;
-   PNG_CONST unsigned int sbit_max = vi->sbit_max;
-   PNG_CONST unsigned int outmax = vi->outmax;
-   PNG_CONST int do_background = vi->do_background;
+   const unsigned int isbit = id >> vi->isbit_shift;
+   const unsigned int sbit_max = vi->sbit_max;
+   const unsigned int outmax = vi->outmax;
+   const int do_background = vi->do_background;
 
    double i;
 
@@ -9452,14 +9591,14 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
    png_infop pi)
 {
    /* Get some constants derived from the input and output file formats: */
-   PNG_CONST png_store* PNG_CONST ps = dp->this.ps;
-   PNG_CONST png_byte in_ct = dp->this.colour_type;
-   PNG_CONST png_byte in_bd = dp->this.bit_depth;
-   PNG_CONST png_uint_32 w = dp->this.w;
-   PNG_CONST png_uint_32 h = dp->this.h;
-   PNG_CONST size_t cbRow = dp->this.cbRow;
-   PNG_CONST png_byte out_ct = png_get_color_type(pp, pi);
-   PNG_CONST png_byte out_bd = png_get_bit_depth(pp, pi);
+   const png_store* const ps = dp->this.ps;
+   const png_byte in_ct = dp->this.colour_type;
+   const png_byte in_bd = dp->this.bit_depth;
+   const png_uint_32 w = dp->this.w;
+   const png_uint_32 h = dp->this.h;
+   const size_t cbRow = dp->this.cbRow;
+   const png_byte out_ct = png_get_color_type(pp, pi);
+   const png_byte out_bd = png_get_bit_depth(pp, pi);
 
    /* There are three sources of error, firstly the quantization in the
     * file encoding, determined by sbit and/or the file depth, secondly
@@ -9500,11 +9639,11 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
     * The basic tests below do not do this, however if 'use_input_precision'
     * is set a subsequent test is performed above.
     */
-   PNG_CONST unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U;
+   const unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U;
    int processing;
    png_uint_32 y;
-   PNG_CONST store_palette_entry *in_palette = dp->this.palette;
-   PNG_CONST int in_is_transparent = dp->this.is_transparent;
+   const store_palette_entry *in_palette = dp->this.palette;
+   const int in_is_transparent = dp->this.is_transparent;
    int process_tRNS;
    int out_npalette = -1;
    int out_is_transparent = 0; /* Just refers to the palette case */
@@ -9552,9 +9691,9 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
             double alpha = 1; /* serves as a flag value */
 
             /* Record the palette index for index images. */
-            PNG_CONST unsigned int in_index =
+            const unsigned int in_index =
                in_ct == 3 ? sample(std, 3, in_bd, x, 0, 0, 0) : 256;
-            PNG_CONST unsigned int out_index =
+            const unsigned int out_index =
                out_ct == 3 ? sample(std, 3, out_bd, x, 0, 0, 0) : 256;
 
             /* Handle input alpha - png_set_background will cause the output
@@ -9563,7 +9702,7 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
             if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 ||
                 (in_ct == 3 && in_is_transparent))
             {
-               PNG_CONST unsigned int input_alpha = in_ct == 3 ?
+               const unsigned int input_alpha = in_ct == 3 ?
                   dp->this.palette[in_index].alpha :
                   sample(std, in_ct, in_bd, x, samples_per_pixel, 0, 0);
 
@@ -9688,15 +9827,15 @@ gamma_end(png_structp ppIn, png_infop pi)
  * maxpc:  maximum percentage error (as a percentage)
  */
 static void
-gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn,
-    PNG_CONST png_byte bit_depthIn, PNG_CONST int palette_numberIn,
-    PNG_CONST int interlace_typeIn,
-    PNG_CONST double file_gammaIn, PNG_CONST double screen_gammaIn,
-    PNG_CONST png_byte sbitIn, PNG_CONST int threshold_testIn,
-    PNG_CONST char *name,
-    PNG_CONST int use_input_precisionIn, PNG_CONST int scale16In,
-    PNG_CONST int expand16In, PNG_CONST int do_backgroundIn,
-    PNG_CONST png_color_16 *bkgd_colorIn, double bkgd_gammaIn)
+gamma_test(png_modifier *pmIn, const png_byte colour_typeIn,
+    const png_byte bit_depthIn, const int palette_numberIn,
+    const int interlace_typeIn,
+    const double file_gammaIn, const double screen_gammaIn,
+    const png_byte sbitIn, const int threshold_testIn,
+    const char *name,
+    const int use_input_precisionIn, const int scale16In,
+    const int expand16In, const int do_backgroundIn,
+    const png_color_16 *bkgd_colorIn, double bkgd_gammaIn)
 {
    gamma_display d;
    context(&pmIn->this, fault);
@@ -9899,11 +10038,11 @@ perform_gamma_threshold_tests(png_modifier *pm)
 }
 
 static void gamma_transform_test(png_modifier *pm,
-   PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth,
-   PNG_CONST int palette_number,
-   PNG_CONST int interlace_type, PNG_CONST double file_gamma,
-   PNG_CONST double screen_gamma, PNG_CONST png_byte sbit,
-   PNG_CONST int use_input_precision, PNG_CONST int scale16)
+   const png_byte colour_type, const png_byte bit_depth,
+   const int palette_number,
+   const int interlace_type, const double file_gamma,
+   const double screen_gamma, const png_byte sbit,
+   const int use_input_precision, const int scale16)
 {
    size_t pos = 0;
    char name[64];
@@ -10056,12 +10195,12 @@ static void perform_gamma_scale16_tests(png_modifier *pm)
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
    defined(PNG_READ_ALPHA_MODE_SUPPORTED)
 static void gamma_composition_test(png_modifier *pm,
-   PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth,
-   PNG_CONST int palette_number,
-   PNG_CONST int interlace_type, PNG_CONST double file_gamma,
-   PNG_CONST double screen_gamma,
-   PNG_CONST int use_input_precision, PNG_CONST int do_background,
-   PNG_CONST int expand_16)
+   const png_byte colour_type, const png_byte bit_depth,
+   const int palette_number,
+   const int interlace_type, const double file_gamma,
+   const double screen_gamma,
+   const int use_input_precision, const int do_background,
+   const int expand_16)
 {
    size_t pos = 0;
    png_const_charp base;
@@ -10448,7 +10587,7 @@ perform_gamma_test(png_modifier *pm, int summary)
  * be indexed adam7[y][x] and notice that the pass numbers are based at
  * 1, not 0 - the base libpng uses.
  */
-static PNG_CONST
+static const
 png_byte adam7[8][8] =
 {
    { 1,6,4,6,2,6,4,6 },
@@ -10799,7 +10938,7 @@ perform_interlace_macro_validation(void)
  * The png_modifier code assumes that encodings[0] is sRGB and treats it
  * specially: do not change the first entry in this list!
  */
-static PNG_CONST color_encoding test_encodings[] =
+static const color_encoding test_encodings[] =
 {
 /* sRGB: must be first in this list! */
 /*gamma:*/ { 1/2.2,
@@ -10821,6 +10960,13 @@ static PNG_CONST color_encoding test_encodings[] =
 /*red:  */ { 0.716500716779386, 0.258728243040113, 0.000000000000000 },
 /*green:*/ { 0.101020574397477, 0.724682314948566, 0.051211818965388 },
 /*blue: */ { 0.146774385252705, 0.016589442011321, 0.773892783545073} },
+#if PNG_LIBPNG_VER >= 10700
+/* Fake encoding which selects just the green channel */
+/*gamma:*/ { 1.45/2.2, /* the 'Mac' gamma */
+/*red:  */ { 0.716500716779386, 0.000000000000000, 0.000000000000000 },
+/*green:*/ { 0.101020574397477, 1.000000000000000, 0.051211818965388 },
+/*blue: */ { 0.146774385252705, 0.000000000000000, 0.773892783545073} },
+#endif
 };
 
 /* signal handler
@@ -10892,11 +11038,11 @@ static void signal_handler(int signum)
 /* main program */
 int main(int argc, char **argv)
 {
-   volatile int summary = 1;  /* Print the error summary at the end */
-   volatile int memstats = 0; /* Print memory statistics at the end */
+   int summary = 1;  /* Print the error summary at the end */
+   int memstats = 0; /* Print memory statistics at the end */
 
    /* Create the given output file on success: */
-   PNG_CONST char *volatile touch = NULL;
+   const char *touch = NULL;
 
    /* This is an array of standard gamma values (believe it or not I've seen
     * every one of these mentioned somewhere.)
@@ -10912,6 +11058,10 @@ int main(int argc, char **argv)
 
    anon_context(&pm.this);
 
+   gnu_volatile(summary)
+   gnu_volatile(memstats)
+   gnu_volatile(touch)
+
    /* Add appropriate signal handlers, just the ANSI specified ones: */
    signal(SIGABRT, signal_handler);
    signal(SIGFPE, signal_handler);
@@ -10967,17 +11117,21 @@ int main(int argc, char **argv)
 #  ifdef PNG_WRITE_tRNS_SUPPORTED
       pm.test_tRNS = 1;
 #  endif
-   pm.test_lbg = 0;
+   pm.test_lbg = PNG_LIBPNG_VER >= 10600;
    pm.test_lbg_gamma_threshold = 1;
-   pm.test_lbg_gamma_transform = 0/*PNG_LIBPNG_VER >= 10700*/;
+   pm.test_lbg_gamma_transform = PNG_LIBPNG_VER >= 10600;
    pm.test_lbg_gamma_sbit = 1;
-   pm.test_lbg_gamma_composition = 0;
+   pm.test_lbg_gamma_composition = PNG_LIBPNG_VER >= 10700;
 
    /* And the test encodings */
    pm.encodings = test_encodings;
    pm.nencodings = ARRAY_SIZE(test_encodings);
 
-   pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */
+#  if PNG_LIBPNG_VER < 10700
+      pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */
+#  else
+      pm.sbitlow = 1U;
+#  endif
 
    /* The following allows results to pass if they correspond to anything in the
     * transformed range [input-.5,input+.5]; this is is required because of the
@@ -11033,7 +11187,8 @@ int main(int argc, char **argv)
       else if (strcmp(*argv, "-q") == 0)
          summary = pm.this.verbose = pm.log = 0;
 
-      else if (strcmp(*argv, "-w") == 0)
+      else if (strcmp(*argv, "-w") == 0 ||
+               strcmp(*argv, "--strict") == 0)
          pm.this.treat_warnings_as_errors = 0;
 
       else if (strcmp(*argv, "--speed") == 0)
@@ -11166,7 +11321,7 @@ int main(int argc, char **argv)
 
       else if (strcmp(*argv, "--interlace") == 0)
       {
-#        ifdef PNG_WRITE_INTERLACING_SUPPORTED
+#        if CAN_WRITE_INTERLACE
             pm.interlace_type = PNG_INTERLACE_ADAM7;
 #        else
             fprintf(stderr, "pngvalid: no write interlace support\n");
@@ -11249,12 +11404,18 @@ int main(int argc, char **argv)
          const char *arg = 9+*argv;
          unsigned char option=0, setting=0;
 
-#ifdef PNG_ARM_NEON_API_SUPPORTED
+#ifdef PNG_ARM_NEON
          if (strncmp(arg, "arm-neon:", 9) == 0)
             option = PNG_ARM_NEON, arg += 9;
 
          else
 #endif
+#ifdef PNG_EXTENSIONS
+         if (strncmp(arg, "extensions:", 11) == 0)
+            option = PNG_EXTENSIONS, arg += 11;
+
+         else
+#endif
 #ifdef PNG_MAXIMUM_INFLATE_WINDOW
          if (strncmp(arg, "max-inflate-window:", 19) == 0)
             option = PNG_MAXIMUM_INFLATE_WINDOW, arg += 19;
diff --git a/contrib/libtests/readpng.c b/contrib/libtests/readpng.c
index 7ba46d0b9..1b489d3f2 100644
--- a/contrib/libtests/readpng.c
+++ b/contrib/libtests/readpng.c
@@ -31,6 +31,13 @@
 #  include "../../png.h"
 #endif
 
+#if PNG_LIBPNG_VER < 10700
+   /* READ_INTERLACING was used instead of READ_DEINTERLACE. */
+#  ifdef PNG_READ_INTERLACING_SUPPORTED
+#     define PNG_READ_DEINTERLACE_SUPPORTED
+#  endif
+#endif
+
 static int
 read_png(FILE *fp)
 {
@@ -70,7 +77,12 @@ read_png(FILE *fp)
 
       {
          png_uint_32 height = png_get_image_height(png_ptr, info_ptr);
-         int passes = png_set_interlace_handling(png_ptr);
+#        ifdef PNG_READ_DEINTERLACE_SUPPORTED
+            int passes = png_set_interlace_handling(png_ptr);
+#        else
+            int passes = png_get_interlace_type(png_ptr, info_ptr) == 
+               PNG_INTERLACE_ADAM7 ? PNG_INTERLACE_ADAM7_PASSES : 1;
+#        endif
          int pass;
 
          png_start_read_image(png_ptr);
@@ -79,6 +91,11 @@ read_png(FILE *fp)
          {
             png_uint_32 y = height;
 
+#           ifndef PNG_READ_DEINTERLACE_SUPPORTED
+               if (passes == PNG_INTERLACE_ADAM7_PASSES)
+                  y = PNG_PASS_ROWS(y, pass);
+#           endif
+
             /* NOTE: this trashes the row each time; interlace handling won't
              * work, but this avoids memory thrashing for speed testing.
              */
diff --git a/contrib/libtests/tarith.c b/contrib/libtests/tarith.c
index cdb00dbf7..cb17ffa76 100644
--- a/contrib/libtests/tarith.c
+++ b/contrib/libtests/tarith.c
@@ -634,7 +634,7 @@ int validation_muldiv(int count, int argc, char **argv)
    {
       png_fixed_point result;
       /* NOTE: your mileage may vary, a type is required below that can
-       * hold 64 bits or more, if floating point is used a 64 bit or
+       * hold 64 bits or more, if floating point is used a 64-bit or
        * better mantissa is required.
        */
       long long int fp, fpround;
@@ -721,7 +721,7 @@ int validation_muldiv(int count, int argc, char **argv)
    }
    while (--count > 0);
 
-   printf("%d tests including %d overflows, %d passed, %d failed (%d 64 bit "
+   printf("%d tests including %d overflows, %d passed, %d failed (%d 64-bit "
       "errors)\n", tested, overflow, passed, error, error64);
    return 0;
 }
@@ -799,13 +799,13 @@ int validation_gamma(int argc, char **argv)
          if (i == 0 && png_log8bit(i) != 0xffffffff ||
              i != 0 && png_log8bit(i) != floor(correct+.5))
          {
-            fprintf(stderr, "8 bit log error: %d: got %u, expected %f\n",
+            fprintf(stderr, "8-bit log error: %d: got %u, expected %f\n",
                i, png_log8bit(i), correct);
          }
       }
 
       if (!silent)
-         printf("maximum 8 bit log error = %f\n", maxerr);
+         printf("maximum 8-bit log error = %f\n", maxerr);
 
       maxerr = 0;
       for (i=0; i<65536; ++i)
@@ -821,14 +821,14 @@ int validation_gamma(int argc, char **argv)
          {
             if (error > .68) /* By experiment error is less than .68 */
             {
-               fprintf(stderr, "16 bit log error: %d: got %u, expected %f"
+               fprintf(stderr, "16-bit log error: %d: got %u, expected %f"
                   " error: %f\n", i, png_log16bit(i), correct, error);
             }
          }
       }
 
       if (!silent)
-         printf("maximum 16 bit log error = %f\n", maxerr);
+         printf("maximum 16-bit log error = %f\n", maxerr);
 
       /* Now exponentiations. */
       maxerr = 0;
@@ -841,13 +841,13 @@ int validation_gamma(int argc, char **argv)
             maxerr = fabs(error);
          if (fabs(error) > 1883) /* By experiment. */
          {
-            fprintf(stderr, "32 bit exp error: %d: got %u, expected %f"
+            fprintf(stderr, "32-bit exp error: %d: got %u, expected %f"
                   " error: %f\n", i, png_exp(i), correct, error);
          }
       }
 
       if (!silent)
-         printf("maximum 32 bit exp error = %f\n", maxerr);
+         printf("maximum 32-bit exp error = %f\n", maxerr);
 
       maxerr = 0;
       for (i=0; i<=0xfffff; ++i)
@@ -859,13 +859,13 @@ int validation_gamma(int argc, char **argv)
             maxerr = fabs(error);
          if (fabs(error) > .50002) /* By experiment */
          {
-            fprintf(stderr, "8 bit exp error: %d: got %u, expected %f"
+            fprintf(stderr, "8-bit exp error: %d: got %u, expected %f"
                   " error: %f\n", i, png_exp8bit(i), correct, error);
          }
       }
 
       if (!silent)
-         printf("maximum 8 bit exp error = %f\n", maxerr);
+         printf("maximum 8-bit exp error = %f\n", maxerr);
 
       maxerr = 0;
       for (i=0; i<=0xfffff; ++i)
@@ -877,13 +877,13 @@ int validation_gamma(int argc, char **argv)
             maxerr = fabs(error);
          if (fabs(error) > .524) /* By experiment */
          {
-            fprintf(stderr, "16 bit exp error: %d: got %u, expected %f"
+            fprintf(stderr, "16-bit exp error: %d: got %u, expected %f"
                   " error: %f\n", i, png_exp16bit(i), correct, error);
          }
       }
 
       if (!silent)
-         printf("maximum 16 bit exp error = %f\n", maxerr);
+         printf("maximum 16-bit exp error = %f\n", maxerr);
    } /* !onlygamma */
 
    /* Test the overall gamma correction. */
@@ -913,7 +913,7 @@ int validation_gamma(int argc, char **argv)
       }
 
       if (!silent)
-         printf("gamma %f: maximum 8 bit error %f\n", g, maxerr);
+         printf("gamma %f: maximum 8-bit error %f\n", g, maxerr);
 
       maxerr = 0;
       for (j=0; j<65536; ++j)
@@ -932,7 +932,7 @@ int validation_gamma(int argc, char **argv)
       }
 
       if (!silent)
-         printf("gamma %f: maximum 16 bit error %f\n", g, maxerr);
+         printf("gamma %f: maximum 16-bit error %f\n", g, maxerr);
    }
 
    return 0;
diff --git a/contrib/pngminus/png2pnm.c b/contrib/pngminus/png2pnm.c
index dff4d0b3d..f68d7ff72 100644
--- a/contrib/pngminus/png2pnm.c
+++ b/contrib/pngminus/png2pnm.c
@@ -266,7 +266,7 @@ BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
     png_set_expand (png_ptr);
 
 #ifdef NJET
-  /* downgrade 16-bit images to 8 bit */
+  /* downgrade 16-bit images to 8-bit */
   if (bit_depth == 16)
     png_set_strip_16 (png_ptr);
   /* transform grayscale images into full-color */
diff --git a/contrib/pngminus/pnm2png.c b/contrib/pngminus/pnm2png.c
index 7bf720f68..8fa64cd1f 100644
--- a/contrib/pngminus/pnm2png.c
+++ b/contrib/pngminus/pnm2png.c
@@ -3,6 +3,7 @@
  *  copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
  *
  *  version 1.0 - 1999.10.15 - First version.
+ *  version 1.1 - 2015.07.29 - Fixed leaks (Glenn Randers-Pehrson)
  *
  *  Permission to use, copy, modify, and distribute this software and
  *  its documentation for any purpose and without fee is hereby granted,
@@ -200,17 +201,17 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
   char          width_token[16];
   char          height_token[16];
   char          maxval_token[16];
-  volatile int           color_type;
+  volatile int    color_type=1;
   unsigned long   ul_width=0, ul_alpha_width=0;
   unsigned long   ul_height=0, ul_alpha_height=0;
   unsigned long   ul_maxval=0;
-  volatile png_uint_32   width, height;
-  volatile png_uint_32   alpha_width, alpha_height;
+  volatile png_uint_32   width=0, height=0;
+  volatile png_uint_32   alpha_width=0, alpha_height=0;
   png_uint_32   maxval;
   volatile int           bit_depth = 0;
-  int           channels;
+  int           channels=0;
   int           alpha_depth = 0;
-  int           alpha_present;
+  int           alpha_present=0;
   int           row, col;
   BOOL          raw, alpha_raw = FALSE;
 #if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
@@ -356,8 +357,10 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
     channels = 3;
   else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
     channels = 4;
+#if 0
   else
-    channels = 0; /* should not happen */
+    channels = 0; /* cannot happen */
+#endif
 
   alpha_present = (channels - 1) % 2;
 
@@ -429,12 +432,16 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
       NULL);
   if (!png_ptr)
   {
+    free (png_pixels);
+    png_pixels = NULL;
     return FALSE;
   }
   info_ptr = png_create_info_struct (png_ptr);
   if (!info_ptr)
   {
     png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
+    free (png_pixels);
+    png_pixels = NULL;
     return FALSE;
   }
 
@@ -449,7 +456,9 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
   /* setjmp() must be called in every function that calls a PNG-reading libpng function */
   if (setjmp (png_jmpbuf(png_ptr)))
   {
-    png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
+    png_destroy_write_struct (&png_ptr, &info_ptr);
+    free (png_pixels);
+    png_pixels = NULL;
     return FALSE;
   }
 
@@ -470,7 +479,9 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
     if ((row_pointers = (png_byte **)
         malloc (height * sizeof (png_bytep))) == NULL)
     {
-      png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
+      png_destroy_write_struct (&png_ptr, &info_ptr);
+      free (png_pixels);
+      png_pixels = NULL;
       return FALSE;
     }
   }
@@ -486,7 +497,7 @@ BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
   png_write_end (png_ptr, info_ptr);
 
   /* clean up after the write, and free any memory allocated */
-  png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
+  png_destroy_write_struct (&png_ptr, &info_ptr);
 
   if (row_pointers != (unsigned char**) NULL)
     free (row_pointers);
diff --git a/contrib/pngsuite/README b/contrib/pngsuite/README
index ec4af9473..a7fde8f36 100644
--- a/contrib/pngsuite/README
+++ b/contrib/pngsuite/README
@@ -1,8 +1,8 @@
 
 pngsuite
 --------
-(c) Willem van Schaik, 1999, 2011, 2012
-Two images are by Glenn Randers-Pehrson, 2012
+Copyright (c) Willem van Schaik, 1999, 2011, 2012
+Two images (ftbbn0g01.png and ftbbn0g02.png) are by Glenn Randers-Pehrson, 2012
 
 Permission to use, copy, modify, and distribute these images for any
 purpose and without fee is hereby granted.
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--- /dev/null
+++ b/contrib/testpngs/makepngs.sh
@@ -0,0 +1,94 @@
+#!/bin/sh
+#
+# Make a set of test PNG files, MAKEPNG is the name of the makepng executable
+# built from contrib/libtests/makepng.c
+
+# Copyright (c) 2015 John Cunningham Bowler
+
+# Last changed in libpng 1.7.0 [(PENDING RELEASE)]
+
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+# The arguments say whether to build all the files or whether just to build the
+# ones that extend the code-coverage of libpng from the existing test files in
+# contrib/pngsuite.
+test -n "$MAKEPNG" || MAKEPNG=./makepng
+opts=
+
+mp(){
+   ${MAKEPNG} $opts $1 "$3" "$4" "$3-$4$2.png"
+}
+
+mpg(){
+   if test "$1" = "none"
+   then
+      mp "" "" "$2" "$3"
+   else
+      mp "--$1" "-$1" "$2" "$3"
+   fi
+}
+
+mptrans(){
+   if test "$1" = "none"
+   then
+      mp "--tRNS" "-tRNS" "$2" "$3"
+   else
+      mp "--tRNS --$1" "-$1-tRNS" "$2" "$3"
+   fi
+}
+
+case "$1" in
+   --small)
+      opts="--small";;&
+
+   --all|--small)
+      for g in none sRGB linear 1.8
+      do
+         for c in gray palette
+         do
+            for b in 1 2 4
+            do
+               mpg "$g" "$c" "$b"
+               mptrans "$g" "$c" "$b"
+            done
+         done
+
+         mpg "$g" palette 8
+         mptrans "$g" palette 8
+
+         for b in 8 16
+         do
+            for c in gray gray-alpha rgb rgb-alpha
+            do
+               mpg "$g" "$c" "$b"
+            done
+            for c in gray rgb
+            do
+               mptrans "$g" "$c" "$b"
+            done
+         done
+      done;;
+
+   --coverage)
+      # Comments below indicate cases known to be required and not duplicated
+      # in other (required) cases; the aim is to get a minimal set that gives
+      # the maxium code coverage.
+      mpg none gray-alpha 8 # required: code coverage, sRGB opaque component
+      mpg none palette 8 # required: basic palette read
+      mpg 1.8 gray 2 # required: tests gamma threshold code
+      mpg 1.8 palette 2 # required: code coverage
+      mpg 1.8 palette 4 # required: code coverage
+      mpg 1.8 palette 8 # error limits only
+      mpg linear palette 8 # error limits only
+      mpg linear rgb-alpha 16 # error limits only
+      mpg sRGB palette 1 # required: code coverage
+      mpg sRGB rgb-alpha 16 # required: code coverage: pngread.c:2422 untested
+      :;;
+
+   *)
+      echo "$0 $1: unknown argument, usage:" >&2
+      echo "  $0 [--all|--coverage|--small]" >&2
+      exit 1
+esac
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diff --git a/contrib/testpngs/rgb-16-linear-tRNS.png b/contrib/testpngs/rgb-16-linear-tRNS.png
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diff --git a/contrib/testpngs/rgb-16-sRGB-tRNS.png b/contrib/testpngs/rgb-16-sRGB-tRNS.png
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diff --git a/contrib/testpngs/rgb-16-sRGB.png b/contrib/testpngs/rgb-16-sRGB.png
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diff --git a/contrib/testpngs/rgb-8-linear-tRNS.png b/contrib/testpngs/rgb-8-linear-tRNS.png
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diff --git a/contrib/testpngs/rgb-8-sRGB-tRNS.png b/contrib/testpngs/rgb-8-sRGB-tRNS.png
new file mode 100644
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diff --git a/contrib/testpngs/rgb-8-sRGB.png b/contrib/testpngs/rgb-8-sRGB.png
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diff --git a/contrib/testpngs/rgb-8-tRNS.png b/contrib/testpngs/rgb-8-tRNS.png
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diff --git a/contrib/testpngs/rgb-8.png b/contrib/testpngs/rgb-8.png
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index 000000000..e69c71bfd
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diff --git a/contrib/testpngs/rgb-alpha-16-1.8.png b/contrib/testpngs/rgb-alpha-16-1.8.png
new file mode 100644
index 000000000..ad65d150e
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diff --git a/contrib/testpngs/rgb-alpha-16-linear.png b/contrib/testpngs/rgb-alpha-16-linear.png
new file mode 100644
index 000000000..1f3990031
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diff --git a/contrib/testpngs/rgb-alpha-16-sRGB.png b/contrib/testpngs/rgb-alpha-16-sRGB.png
new file mode 100644
index 000000000..d9cea633a
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diff --git a/contrib/testpngs/rgb-alpha-16.png b/contrib/testpngs/rgb-alpha-16.png
new file mode 100644
index 000000000..59262397e
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diff --git a/contrib/testpngs/rgb-alpha-8-1.8.png b/contrib/testpngs/rgb-alpha-8-1.8.png
new file mode 100644
index 000000000..f4d08ec04
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diff --git a/contrib/testpngs/rgb-alpha-8-linear.png b/contrib/testpngs/rgb-alpha-8-linear.png
new file mode 100644
index 000000000..b4f8bc829
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diff --git a/contrib/testpngs/rgb-alpha-8-sRGB.png b/contrib/testpngs/rgb-alpha-8-sRGB.png
new file mode 100644
index 000000000..f06e7f837
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diff --git a/contrib/testpngs/rgb-alpha-8.png b/contrib/testpngs/rgb-alpha-8.png
new file mode 100644
index 000000000..e15d4913f
Binary files /dev/null and b/contrib/testpngs/rgb-alpha-8.png differ
diff --git a/contrib/tools/pngfix.c b/contrib/tools/pngfix.c
index 2489ac374..ce16c0dca 100644
--- a/contrib/tools/pngfix.c
+++ b/contrib/tools/pngfix.c
@@ -52,7 +52,10 @@
 #ifdef PNG_SETJMP_SUPPORTED
 #include <setjmp.h>
 
-#if defined(PNG_READ_SUPPORTED) && defined(PNG_EASY_ACCESS_SUPPORTED)
+#if defined(PNG_READ_SUPPORTED) && defined(PNG_EASY_ACCESS_SUPPORTED) &&\
+   (defined(PNG_READ_DEINTERLACE_SUPPORTED) ||\
+    defined(PNG_READ_INTERLACING_SUPPORTED))
+
 /* zlib.h defines the structure z_stream, an instance of which is included
  * in this structure and is required for decompressing the LZ compressed
  * data in PNG files.
@@ -134,7 +137,7 @@
 #define png_zTXt PNG_U32(122,  84,  88, 116)
 #endif
 
-/* The 8 byte signature as a pair of 32 bit quantities */
+/* The 8-byte signature as a pair of 32-bit quantities */
 #define sig1 PNG_U32(137,  80,  78,  71)
 #define sig2 PNG_U32( 13,  10,  26,  10)
 
@@ -156,7 +159,7 @@
  */
 #define UNREACHED 0
 
-/* 80-bit number handling - a PNG image can be up to (2^31-1)x(2^31-1) 8 byte
+/* 80-bit number handling - a PNG image can be up to (2^31-1)x(2^31-1) 8-byte
  * (16-bit RGBA) pixels in size; that's less than 2^65 bytes or 2^68 bits, so
  * arithmetic of 80-bit numbers is sufficient.  This representation uses an
  * arbitrary length array of png_uint_16 digits (0..65535).  The representation
@@ -584,7 +587,7 @@ chunk_type_valid(png_uint_32 c)
    c &= ~PNG_U32(32,32,0,32);
    t = (c & ~0x1f1f1f1f) ^ 0x40404040;
 
-   /* Subtract 65 for each 8 bit quantity, this must not overflow
+   /* Subtract 65 for each 8-bit quantity, this must not overflow
     * and each byte must then be in the range 0-25.
     */
    c -= PNG_U32(65,65,65,65);
@@ -667,7 +670,7 @@ IDAT_list_extend(struct IDAT_list *tail)
 
       if (length < tail->length) /* arithmetic overflow */
          length = tail->length;
-            
+
       next = voidcast(IDAT_list*, malloc(IDAT_list_size(NULL, length)));
       CLEAR(*next);
 
@@ -921,7 +924,7 @@ emit_string(const char *str, FILE *out)
 
       else if (isspace(UCHAR_MAX & *str))
          putc('_', out);
-   
+
       else
          fprintf(out, "\\%.3o", *str);
 }
@@ -1945,7 +1948,7 @@ process_IDAT(struct file *file)
       list->count = 0;
       file->idat->idat_list_tail = list;
    }
-   
+
    /* And fill in the next IDAT information buffer. */
    list->lengths[(list->count)++] = file->chunk->chunk_length;
 
@@ -2585,7 +2588,7 @@ zlib_run(struct zlib *zlib)
    {
       struct chunk *chunk = zlib->chunk;
       int rc;
-      
+
       assert(zlib->rewrite_offset < chunk->chunk_length);
 
       rc = zlib_advance(zlib, chunk->chunk_length - zlib->rewrite_offset);
@@ -4030,7 +4033,7 @@ main(void)
 int
 main(void)
 {
-   fprintf(stderr, "pngfix does not work without read support\n");
+   fprintf(stderr, "pngfix does not work without read deinterlace support\n");
    return 77;
 }
 #endif /* PNG_READ_SUPPORTED && PNG_EASY_ACCESS_SUPPORTED */
diff --git a/contrib/visupng/PngFile.c b/contrib/visupng/PngFile.c
index e563e9292..dcde18a3a 100644
--- a/contrib/visupng/PngFile.c
+++ b/contrib/visupng/PngFile.c
@@ -136,7 +136,7 @@ BOOL PngLoadImage (PTSTR pstrFileName, png_byte **ppbImageData,
 
     /* create the two png(-info) structures */
 
-    png_ptr = png_create_read_struct(png_get_libpng_ver(NULL), NULL,
+    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
       (png_error_ptr)png_cexcept_error, (png_error_ptr)NULL);
     if (!png_ptr)
     {
@@ -313,7 +313,7 @@ BOOL PngSaveImage (PTSTR pstrFileName, png_byte *pDiData,
 
     /* prepare the standard PNG structures */
 
-    png_ptr = png_create_write_struct(png_get_libpng_ver(NULL), NULL,
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL,
       (png_error_ptr)png_cexcept_error, (png_error_ptr)NULL);
     if (!png_ptr)
     {
diff --git a/contrib/visupng/cexcept.h b/contrib/visupng/cexcept.h
index e28f3e9e4..5f45d7697 100644
--- a/contrib/visupng/cexcept.h
+++ b/contrib/visupng/cexcept.h
@@ -1,12 +1,11 @@
 /*===
-cexcept.h 2.0.1 (2008-Jul-19-Sat, modified 2015-Jun-03-Mon)
+cexcept.h 2.0.1 (2008-Jul-19-Sat)
 http://www.nicemice.net/cexcept/
 Adam M. Costello
 http://www.nicemice.net/amc/
 
 An interface for exception-handling in ANSI C (C89 and subsequent ISO
-standards), developed jointly with Cosmin Truta.  Revised by John Bowler,
-June 2015, to declare exception_env and exception_prev "volatile".
+standards), developed jointly with Cosmin Truta.
 
     Copyright (c) 2000-2008 Adam M. Costello and Cosmin Truta.
     This software may be modified only if its author and version
@@ -211,7 +210,7 @@ struct exception_context { \
 
 #define Try \
   { \
-    jmp_buf * volatile exception__prev, exception__env; \
+    jmp_buf *exception__prev, exception__env; \
     exception__prev = the_exception_context->penv; \
     the_exception_context->penv = &exception__env; \
     if (setjmp(exception__env) == 0) { \
diff --git a/example.c b/example.c
index 945546c25..f8591e668 100644
--- a/example.c
+++ b/example.c
@@ -271,7 +271,7 @@ void read_png(char *file_name)  /* We need to open the file */
 {
    png_structp png_ptr;
    png_infop info_ptr;
-   unsigned int sig_read = 0;
+   int sig_read = 0;
    png_uint_32 width, height;
    int bit_depth, color_type, interlace_type;
    FILE *fp;
@@ -280,7 +280,7 @@ void read_png(char *file_name)  /* We need to open the file */
       return (ERROR);
 
 #else no_open_file /* prototype 2 */
-void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
+void read_png(FILE *fp, int sig_read)  /* File is already open */
 {
    png_structp png_ptr;
    png_infop info_ptr;
@@ -370,7 +370,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
     * are mutually exclusive.
     */
 
-   /* Tell libpng to strip 16 bit/color files down to 8 bits/color.
+   /* Tell libpng to strip 16 bits/color files down to 8 bits/color.
     * Use accurate scaling if it's available, otherwise just chop off the
     * low byte.
     */
@@ -466,7 +466,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
    }
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-   /* Quantize RGB files down to 8 bit palette or reduce palettes
+   /* Quantize RGB files down to 8-bit palette or reduce palettes
     * to the number of colors available on your screen.
     */
    if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
@@ -518,11 +518,11 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
    /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
    png_set_swap_alpha(png_ptr);
 
-   /* Swap bytes of 16 bit files to least significant byte first */
+   /* Swap bytes of 16-bit files to least significant byte first */
    png_set_swap(png_ptr);
 
    /* Add filler (or alpha) byte (before/after each RGB triplet) */
-   png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
+   png_set_filler(png_ptr, 0xffff, PNG_FILLER_AFTER);
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Turn on interlace handling.  REQUIRED if you are not using
@@ -966,7 +966,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    /* Swap bytes of 16-bit files to most significant byte first */
    png_set_swap(png_ptr);
 
-   /* Swap bits of 1, 2, 4 bit packed pixel formats */
+   /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
    png_set_packswap(png_ptr);
 
    /* Turn on interlace handling if you are not using png_write_image() */
diff --git a/libpng-manual.txt b/libpng-manual.txt
index da247cf84..bc7a441cf 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.18 - July 23, 2015
+ libpng version 1.6.19 - November 12, 2015
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.18 - July 23, 2015
+ libpng versions 0.97, January 1998, through 1.6.19 - November 12, 2015
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
 
@@ -70,15 +70,16 @@ a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
 The W3C and ISO documents have identical technical content.
 
 The PNG-1.2 specification is available at
-<http://www.libpng.org/pub/png/documents/>.  It is technically equivalent
+<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
+It is technically equivalent
 to the PNG specification (second edition) but has some additional material.
 
-The PNG-1.0 specification is available
-as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
-W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
+The PNG-1.0 specification is available as RFC 2083 
+<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
 
 Some additional chunks are described in the special-purpose public chunks
-documents at <http://www.libpng.org/pub/png/documents/>.
+documents at <http://www.libpng.org/pub/png/spec/register/>
 
 Other information
 about PNG, and the latest version of libpng, can be found at the PNG home
@@ -100,7 +101,7 @@ majority of the needs of its users.
 
 Libpng uses zlib for its compression and decompression of PNG files.
 Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
+be found at the zlib home page, <http://zlib.net/>.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
@@ -649,6 +650,7 @@ User limits
 
 The PNG specification allows the width and height of an image to be as
 large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
+For safety, libpng imposes a default limit of 1 million rows and columns.
 Larger images will be rejected immediately with a png_error() call. If
 you wish to change these limits, you can use
 
@@ -669,8 +671,11 @@ If you need to retrieve the limits that are being applied, use
    height_max = png_get_user_height_max(png_ptr);
 
 The PNG specification sets no limit on the number of ancillary chunks
-allowed in a PNG datastream.  You can impose a limit on the total number
-of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
+allowed in a PNG datastream.  By default, libpng imposes a limit of
+a total of 1000 sPLT, tEXt, iTXt, zTXt, and unknown chunks to be stored.
+If you have set up both info_ptr and end_info_ptr, the limit applies
+separately to each.  You can change the limit on the total number of such
+chunks that will be stored, with
 
    png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
 
@@ -678,8 +683,9 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
 
    chunk_cache_max = png_get_chunk_cache_max(png_ptr);
 
-You can also set a limit on the amount of memory that a compressed chunk
-other than IDAT can occupy, with
+Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
+memory that a compressed chunk other than IDAT can occupy, when decompressed.
+You can change this limit with
 
    png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
 
@@ -1679,15 +1685,16 @@ described below.
 Data will be decoded into the supplied row buffers packed into bytes
 unless the library has been told to transform it into another format.
 For example, 4 bit/pixel paletted or grayscale data will be returned
-2 pixels/byte with the leftmost pixel in the high-order bits of the
-byte, unless png_set_packing() is called.  8-bit RGB data will be stored
+2 pixels/byte with the leftmost pixel in the high-order bits of the byte,
+unless png_set_packing() is called.  8-bit RGB data will be stored
 in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
 is called to insert filler bytes, either before or after each RGB triplet.
+
 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
 byte of the color value first, unless png_set_scale_16() is called to
 transform it to regular RGB RGB triplets, or png_set_filler() or
-png_set_add alpha() is called to insert filler bytes, either before or
-after each RRGGBB triplet.  Similarly, 8-bit or 16-bit grayscale data can
+png_set_add alpha() is called to insert two filler bytes, either before
+or after each RRGGBB triplet.  Similarly, 8-bit or 16-bit grayscale data can
 be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
 or png_set_scale_16().
 
@@ -1844,12 +1851,13 @@ into 4 or 8 bytes for windowing systems that need them in this format:
     if (color_type == PNG_COLOR_TYPE_RGB)
        png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
 
-where "filler" is the 8 or 16-bit number to fill with, and the location is
-either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
-you want the filler before the RGB or after.  This transformation
-does not affect images that already have full alpha channels.  To add an
-opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
-will generate RGBA pixels.
+where "filler" is the 8-bit or 16-bit number to fill with, and the location
+is either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
+you want the filler before the RGB or after. When filling an 8-bit pixel,
+the least significant 8 bits of the number are used, if a 16-bit number is
+supplied.  This transformation does not affect images that already have full
+alpha channels.  To add an opaque alpha channel, use filler=0xffff and
+PNG_FILLER_AFTER which will generate RGBA pixels.
 
 Note that png_set_filler() does not change the color type.  If you want
 to do that, you can add a true alpha channel with
@@ -1859,7 +1867,7 @@ to do that, you can add a true alpha channel with
        png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
 
 where "filler" contains the alpha value to assign to each pixel.
-This function was added in libpng-1.2.7.
+The png_set_add_alpha() function was added in libpng-1.2.7.
 
 If you are reading an image with an alpha channel, and you need the
 data as ARGB instead of the normal PNG format RGBA:
@@ -1917,9 +1925,9 @@ data for sBIT, regardless of the error_action setting.
 The default values come from the PNG file cHRM chunk if present; otherwise, the
 defaults correspond to the ITU-R recommendation 709, and also the sRGB color
 space, as recommended in the Charles Poynton's Colour FAQ,
-<http://www.poynton.com/>, in section 9:
+Copyright (c) 2006-11-28 Charles Poynton, in section 9:
 
-   <http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
+<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
 
     Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
 
@@ -3716,21 +3724,26 @@ as a wide variety of APIs to manipulate ancilliary information.
 
 To read a PNG file using the simplified API:
 
-  1) Declare a 'png_image' structure (see below) on the
-     stack and memset() it to all zero.
+  1) Declare a 'png_image' structure (see below) on the stack, set the
+     version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
+     (this is REQUIRED, your program may crash if you don't do it.)
 
   2) Call the appropriate png_image_begin_read... function.
 
-  3) Set the png_image 'format' member to the required
-     format and allocate a buffer for the image.
+  3) Set the png_image 'format' member to the required sample format.
 
-  4) Call png_image_finish_read to read the image into
-     your buffer.
+  4) Allocate a buffer for the image and, if required, the color-map.
+
+  5) Call png_image_finish_read to read the image and, if required, the
+     color-map into your buffers.
 
 There are no restrictions on the format of the PNG input itself; all valid
 color types, bit depths, and interlace methods are acceptable, and the
 input image is transformed as necessary to the requested in-memory format
-during the png_image_finish_read() step.
+during the png_image_finish_read() step.  The only caveat is that if you
+request a color-mapped image from a PNG that is full-color or makes
+complex use of an alpha channel the transformation is extremely lossy and the
+result may look terrible.
 
 To write a PNG file using the simplified API:
 
@@ -3739,34 +3752,35 @@ To write a PNG file using the simplified API:
 
   2) Initialize the members of the structure that describe the
      image, setting the 'format' member to the format of the
-     image in memory.
+     image samples.
 
   3) Call the appropriate png_image_write... function with a
-     pointer to the image to write the PNG data.
+     pointer to the image and, if necessary, the color-map to write
+     the PNG data.
 
 png_image is a structure that describes the in-memory format of an image
-when it is being read or define the in-memory format of an image that you
+when it is being read or defines the in-memory format of an image that you
 need to write.  The "png_image" structure contains the following members:
 
+   png_controlp opaque  Initialize to NULL, free with png_image_free
    png_uint_32  version Set to PNG_IMAGE_VERSION
    png_uint_32  width   Image width in pixels (columns)
    png_uint_32  height  Image height in pixels (rows)
    png_uint_32  format  Image format as defined below
    png_uint_32  flags   A bit mask containing informational flags
-   png_controlp opaque  Initialize to NULL, free with png_image_free
    png_uint_32  colormap_entries; Number of entries in the color-map
    png_uint_32  warning_or_error;
    char         message[64];
 
-In the event of an error or warning the following field warning_or_error
+In the event of an error or warning the "warning_or_error"
 field will be set to a non-zero value and the 'message' field will contain
 a '\0' terminated string with the libpng error or warning message.  If both
 warnings and an error were encountered, only the error is recorded.  If there
 are multiple warnings, only the first one is recorded.
 
-The upper 30 bits of this value are reserved; the low two bits contain
-a two bit code such that a value more than 1 indicates a failure in the API
-just called:
+The upper 30 bits of the "warning_or_error" value are reserved; the low two
+bits contain a two bit code such that a value more than 1 indicates a failure
+in the API just called:
 
    0 - no warning or error
    1 - warning
@@ -3798,64 +3812,72 @@ channels are linear.  Color channels use the RGB encoding (RGB end-points) of
 the sRGB specification.  This encoding is identified by the
 PNG_FORMAT_FLAG_LINEAR flag below.
 
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
 When an alpha channel is present it is expected to denote pixel coverage
 of the color or luminance channels and is returned as an associated alpha
 channel: the color/gray channels are scaled (pre-multiplied) by the alpha
 value.
 
-When a color-mapped image is used as a result of calling
-png_image_read_colormap or png_image_write_colormap the channels are encoded
-in the color-map and the descriptions above apply to the color-map entries.
-The image data is encoded as small integers, value 0..255, that index the
-entries in the color-map.  One integer (one byte) is stored for each pixel.
+The samples are either contained directly in the image data, between 1 and 8
+bytes per pixel according to the encoding, or are held in a color-map indexed
+by bytes in the image data.  In the case of a color-map the color-map entries
+are individual samples, encoded as above, and the image data has one byte per
+pixel to select the relevant sample from the color-map.
 
 PNG_FORMAT_*
 
 The #defines to be used in png_image::format.  Each #define identifies a
 particular layout of channel data and, if present, alpha values.  There are
-separate defines for each of the two channel encodings.
+separate defines for each of the two component encodings.
 
-A format is built up using single bit flag values.  Not all combinations are
-valid: use the bit flag values below for testing a format returned by the
-read APIs, but set formats from the derived values.
+A format is built up using single bit flag values.  All combinations are
+valid.  Formats can be built up from the flag values or you can use one of
+the predefined values below.  When testing formats always use the FORMAT_FLAG
+macros to test for individual features - future versions of the library may
+add new flags.
 
 When reading or writing color-mapped images the format should be set to the
 format of the entries in the color-map then png_image_{read,write}_colormap
 called to read or write the color-map and set the format correctly for the
 image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
 
-NOTE: libpng can be built with particular features disabled, if you see
+NOTE: libpng can be built with particular features disabled. If you see
 compiler errors because the definition of one of the following flags has been
 compiled out it is because libpng does not have the required support.  It is
 possible, however, for the libpng configuration to enable the format on just
-read or just write; in that case you may see an error at run time.  You can
-guard against this by checking for the definition of:
+read or just write; in that case you may see an error at run time.
+You can guard against this by checking for the definition of the
+appropriate "_SUPPORTED" macro, one of:
 
    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
 
-   PNG_FORMAT_FLAG_ALPHA    0x01 format with an alpha channel
-   PNG_FORMAT_FLAG_COLOR    0x02 color format: otherwise grayscale
-   PNG_FORMAT_FLAG_LINEAR   0x04 png_uint_16 channels else png_byte
-   PNG_FORMAT_FLAG_COLORMAP 0x08 libpng use only
-   PNG_FORMAT_FLAG_BGR      0x10 BGR colors, else order is RGB
-   PNG_FORMAT_FLAG_AFIRST   0x20 alpha channel comes first
+   PNG_FORMAT_FLAG_ALPHA    format with an alpha channel
+   PNG_FORMAT_FLAG_COLOR    color format: otherwise grayscale
+   PNG_FORMAT_FLAG_LINEAR   2-byte channels else 1-byte
+   PNG_FORMAT_FLAG_COLORMAP image data is color-mapped
+   PNG_FORMAT_FLAG_BGR      BGR colors, else order is RGB
+   PNG_FORMAT_FLAG_AFIRST   alpha channel comes first
 
 Supported formats are as follows.  Future versions of libpng may support more
 formats; for compatibility with older versions simply check if the format
 macro is defined using #ifdef.  These defines describe the in-memory layout
 of the components of the pixels of the image.
 
-First the single byte formats:
+First the single byte (sRGB) formats:
 
-   PNG_FORMAT_GRAY 0
-   PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
-   PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
-   PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
-   PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
-   PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
-   PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
-   PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
-   PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
+   PNG_FORMAT_GRAY
+   PNG_FORMAT_GA
+   PNG_FORMAT_AG
+   PNG_FORMAT_RGB
+   PNG_FORMAT_BGR
+   PNG_FORMAT_RGBA
+   PNG_FORMAT_ARGB
+   PNG_FORMAT_BGRA
+   PNG_FORMAT_ABGR
 
 Then the linear 2-byte formats.  When naming these "Y" is used to
 indicate a luminance (gray) channel.  The component order within the pixel
@@ -3864,22 +3886,22 @@ components in the linear format.  The components are 16-bit integers in
 the native byte order for your platform, and there is no provision for
 swapping the bytes to a different endian condition.
 
-   PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
+   PNG_FORMAT_LINEAR_Y
    PNG_FORMAT_LINEAR_Y_ALPHA
-      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
    PNG_FORMAT_LINEAR_RGB
-      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
    PNG_FORMAT_LINEAR_RGB_ALPHA
-      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|
-      PNG_FORMAT_FLAG_ALPHA)
 
-Color-mapped formats are obtained by calling png_image_{read,write}_colormap,
-as appropriate after setting png_image::format to the format of the color-map
-to be read or written.  Applications may check the value of
-PNG_FORMAT_FLAG_COLORMAP to see if they have called the colormap API.  The
-format of the color-map may be extracted using the following macro.
+With color-mapped formats the image data is one byte for each pixel. The byte
+is an index into the color-map which is formatted as above.  To obtain a
+color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
+to one of the above definitions, or you can use one of the definitions below.
 
-   PNG_FORMAT_OF_COLORMAP(fmt) ((fmt) & ~PNG_FORMAT_FLAG_COLORMAP)
+   PNG_FORMAT_RGB_COLORMAP
+   PNG_FORMAT_BGR_COLORMAP
+   PNG_FORMAT_RGBA_COLORMAP
+   PNG_FORMAT_ARGB_COLORMAP
+   PNG_FORMAT_BGRA_COLORMAP
+   PNG_FORMAT_ABGR_COLORMAP
 
 PNG_IMAGE macros
 
@@ -3887,9 +3909,9 @@ These are convenience macros to derive information from a png_image
 structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
 actual image sample values - either the entries in the color-map or the
 pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
-for the pixels and will always return 1 after a call to
-png_image_{read,write}_colormap.  The remaining macros return information
-about the rows in the image and the complete image.
+for the pixels and will always return 1 for color-mapped formats.  The
+remaining macros return information about the rows in the image and the
+complete image.
 
 NOTE: All the macros that take a png_image::format parameter are compile time
 constants if the format parameter is, itself, a constant.  Therefore these
@@ -3897,46 +3919,39 @@ macros can be used in array declarations and case labels where required.
 Similarly the macros are also pre-processor constants (sizeof is not used) so
 they can be used in #if tests.
 
-First the information about the samples.
-
   PNG_IMAGE_SAMPLE_CHANNELS(fmt)
     Returns the total number of channels in a given format: 1..4
 
   PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)
     Returns the size in bytes of a single component of a pixel or color-map
-    entry (as appropriate) in the image.
+    entry (as appropriate) in the image: 1 or 2.
 
   PNG_IMAGE_SAMPLE_SIZE(fmt)
     This is the size of the sample data for one sample.  If the image is
     color-mapped it is the size of one color-map entry (and image pixels are
     one byte in size), otherwise it is the size of one image pixel.
 
+  PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)
+    The maximum size of the color-map required by the format expressed in a
+    count of components.  This can be used to compile-time allocate a
+    color-map:
+
+    png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+
+    png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+
+    Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+    information from one of the png_image_begin_read_ APIs and dynamically
+    allocate the required memory.
+
   PNG_IMAGE_COLORMAP_SIZE(fmt)
    The size of the color-map required by the format; this is the size of the
-   color-map buffer passed to the png_image_{read,write}_colormap APIs, it is
+   color-map buffer passed to the png_image_{read,write}_colormap APIs. It is
    a fixed number determined by the format so can easily be allocated on the
    stack if necessary.
 
-#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
-   (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
-   /* The maximum size of the color-map required by the format expressed in a
-    * count of components.  This can be used to compile-time allocate a
-    * color-map:
-    *
-    * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
-    *
-    * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
-    *
-    * Alternatively, use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
-    * information from one of the png_image_begin_read_ APIs and dynamically
-    * allocate the required memory.
-    */
-
-
 Corresponding information about the pixels
 
-  PNG_IMAGE_PIXEL_(test,fmt)
-
   PNG_IMAGE_PIXEL_CHANNELS(fmt)
    The number of separate channels (components) in a pixel; 1 for a
    color-mapped image.
@@ -3962,19 +3977,54 @@ Information about the whole row, or whole image
    to start the next row on a 4-byte boundary.
 
   PNG_IMAGE_BUFFER_SIZE(image, row_stride)
-    Returns the size, in bytes, of an image buffer given a png_image and a row
-    stride - the number of components to leave space for in each row.  This
-    macro takes care of multiplying row_stride by PNG_IMAGE_PIXEL_COMONENT_SIZE
-    when the image has 2-byte components.
+   Return the size, in bytes, of an image buffer given a png_image and a row
+   stride - the number of components to leave space for in each row.
+
+  PNG_IMAGE_SIZE(image)
+   Return the size, in bytes, of the image in memory given just a png_image;
+   the row stride is the minimum stride required for the image.
+
+  PNG_IMAGE_COLORMAP_SIZE(image)
+   Return the size, in bytes, of the color-map of this image.  If the image
+   format is not a color-map format this will return a size sufficient for
+   256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
+   you don't want to allocate a color-map in this case.
+
+PNG_IMAGE_FLAG_*
+
+Flags containing additional information about the image are held in
+the 'flags' field of png_image.
 
   PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
     This indicates the the RGB values of the in-memory bitmap do not
     correspond to the red, green and blue end-points defined by sRGB.
 
-  PNG_IMAGE_FLAG_COLORMAP == 0x02
-    The PNG is color-mapped.  If this flag is set png_image_read_colormap
-    can be used without further loss of image information.  If it is not set
-    png_image_read_colormap will cause significant loss if the image has any
+  PNG_IMAGE_FLAG_FAST == 0x02
+   On write emphasise speed over compression; the resultant PNG file will be
+   larger but will be produced significantly faster, particular for large
+   images.  Do not use this option for images which will be distributed, only
+   used it when producing intermediate files that will be read back in
+   repeatedly.  For a typical 24-bit image the option will double the read
+   speed at the cost of increasing the image size by 25%, however for many
+   more compressible images the PNG file can be 10 times larger with only a
+   slight speed gain.
+
+  PNG_IMAGE_FLAG_16BIT_sRGB == 0x04
+    On read if the image is a 16-bit per component image and there is no gAMA
+    or sRGB chunk assume that the components are sRGB encoded.  Notice that
+    images output by the simplified API always have gamma information; setting
+    this flag only affects the interpretation of 16-bit images from an
+    external source.  It is recommended that the application expose this flag
+    to the user; the user can normally easily recognize the difference between
+    linear and sRGB encoding.  This flag has no effect on write - the data
+    passed to the write APIs must have the correct encoding (as defined
+    above.)
+
+    If the flag is not set (the default) input 16-bit per component data is
+    assumed to be linear.
+
+    NOTE: the flag can only be set after the png_image_begin_read_ call,
+    because that call initializes the 'flags' field.
 
 READ APIs
 
@@ -4856,7 +4906,7 @@ limits are now
    png_user_chunk_malloc_max 0 (unlimited) 8,000,000
 
 The png_set_option() function (and the "options" member of the png struct) was
-added to libpng-1.5.15.
+added to libpng-1.5.15, with option PNG_ARM_NEON.
 
 The library now supports a complete fixed point implementation and can
 thus be used on systems that have no floating point support or very
@@ -4998,9 +5048,9 @@ The signatures of many exported functions were changed, such that
    png_infop became png_inforp or png_const_inforp
 where "rp" indicates a "restricted pointer".
 
-The support for FAR/far types has been eliminated and the definition of
-png_alloc_size_t is now controlled by a flag so that 'small size_t' systems
-can select it if necessary.
+Dropped support for 16-bit platforms. The support for FAR/far types has
+been eliminated and the definition of png_alloc_size_t is now controlled
+by a flag so that 'small size_t' systems can select it if necessary.
 
 Error detection in some chunks has improved; in particular the iCCP chunk
 reader now does pretty complete validation of the basic format.  Some bad
@@ -5092,6 +5142,11 @@ It can be set for testing debug or beta builds to ensure that they will compile
 when the build type is switched to RC or STABLE. In essence this overrides the
 PNG_LIBPNG_BUILD_BASE_TYPE definition which is not directly user controllable.
 
+Starting with libpng-1.6.19, attempting to set an over-length PLTE chunk
+is an error. Previously this requirement of the PNG specification was not
+enforced, and the palette was always limited to 256 entries. An over-length
+PLTE chunk found in an input PNG is silently truncated.
+
 XIII.  Detecting libpng
 
 The png_get_io_ptr() function has been present since libpng-0.88, has never
@@ -5245,10 +5300,12 @@ We prefer #ifdef and #ifndef to #if defined() and #if !defined()
 when there is only one macro being tested.  We always use parentheses
 with "defined".
 
-We prefer to express integers that are used as bit masks in hex format,
-with an even number of lower-case hex digits (e.g., 0x00, 0xff, 0x0100).
+We express integer constants that are used as bit masks in hex format,
+with an even number of lower-case hex digits, and to make them unsigned
+(e.g., 0x00U, 0xffU, 0x0100U) and long if they are greater than 0x7fff
+(e.g., 0xffffUL).
 
-We prefer to use underscores in variable names rather than camelCase, except
+We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.
 
 We prefer "if (something != 0)" and "if (something == 0)"
@@ -5262,13 +5319,11 @@ Other rules can be inferred by inspecting the libpng source.
 
 XVI. Y2K Compliance in libpng
 
-July 23, 2015
-
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.18 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.19 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer
diff --git a/libpng.3 b/libpng.3
index bb079d43e..774760ca0 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "July 23, 2015"
+.TH LIBPNG 3 "November 12, 2015"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.18
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.19
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -508,7 +508,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.18 - July 23, 2015
+ libpng version 1.6.19 - November 12, 2015
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
@@ -519,7 +519,7 @@ libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.18 - July 23, 2015
+ libpng versions 0.97, January 1998, through 1.6.19 - November 12, 2015
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
 
@@ -578,15 +578,16 @@ a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
 The W3C and ISO documents have identical technical content.
 
 The PNG-1.2 specification is available at
-<http://www.libpng.org/pub/png/documents/>.  It is technically equivalent
+<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
+It is technically equivalent
 to the PNG specification (second edition) but has some additional material.
 
-The PNG-1.0 specification is available
-as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
-W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
+The PNG-1.0 specification is available as RFC 2083 
+<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
 
 Some additional chunks are described in the special-purpose public chunks
-documents at <http://www.libpng.org/pub/png/documents/>.
+documents at <http://www.libpng.org/pub/png/spec/register/>
 
 Other information
 about PNG, and the latest version of libpng, can be found at the PNG home
@@ -608,7 +609,7 @@ majority of the needs of its users.
 
 Libpng uses zlib for its compression and decompression of PNG files.
 Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
+be found at the zlib home page, <http://zlib.net/>.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
@@ -1157,6 +1158,7 @@ callback function:
 
 The PNG specification allows the width and height of an image to be as
 large as 2^(31\-1 (0x7fffffff), or about 2.147 billion rows and columns.
+For safety, libpng imposes a default limit of 1 million rows and columns.
 Larger images will be rejected immediately with a png_error() call. If
 you wish to change these limits, you can use
 
@@ -1177,8 +1179,11 @@ If you need to retrieve the limits that are being applied, use
    height_max = png_get_user_height_max(png_ptr);
 
 The PNG specification sets no limit on the number of ancillary chunks
-allowed in a PNG datastream.  You can impose a limit on the total number
-of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
+allowed in a PNG datastream.  By default, libpng imposes a limit of
+a total of 1000 sPLT, tEXt, iTXt, zTXt, and unknown chunks to be stored.
+If you have set up both info_ptr and end_info_ptr, the limit applies
+separately to each.  You can change the limit on the total number of such
+chunks that will be stored, with
 
    png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
 
@@ -1186,8 +1191,9 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
 
    chunk_cache_max = png_get_chunk_cache_max(png_ptr);
 
-You can also set a limit on the amount of memory that a compressed chunk
-other than IDAT can occupy, with
+Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
+memory that a compressed chunk other than IDAT can occupy, when decompressed.
+You can change this limit with
 
    png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
 
@@ -2187,15 +2193,16 @@ described below.
 Data will be decoded into the supplied row buffers packed into bytes
 unless the library has been told to transform it into another format.
 For example, 4 bit/pixel paletted or grayscale data will be returned
-2 pixels/byte with the leftmost pixel in the high-order bits of the
-byte, unless png_set_packing() is called.  8-bit RGB data will be stored
+2 pixels/byte with the leftmost pixel in the high-order bits of the byte,
+unless png_set_packing() is called.  8-bit RGB data will be stored
 in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
 is called to insert filler bytes, either before or after each RGB triplet.
+
 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
 byte of the color value first, unless png_set_scale_16() is called to
 transform it to regular RGB RGB triplets, or png_set_filler() or
-png_set_add alpha() is called to insert filler bytes, either before or
-after each RRGGBB triplet.  Similarly, 8-bit or 16-bit grayscale data can
+png_set_add alpha() is called to insert two filler bytes, either before
+or after each RRGGBB triplet.  Similarly, 8-bit or 16-bit grayscale data can
 be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
 or png_set_scale_16().
 
@@ -2352,12 +2359,13 @@ into 4 or 8 bytes for windowing systems that need them in this format:
     if (color_type == PNG_COLOR_TYPE_RGB)
        png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
 
-where "filler" is the 8 or 16-bit number to fill with, and the location is
-either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
-you want the filler before the RGB or after.  This transformation
-does not affect images that already have full alpha channels.  To add an
-opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
-will generate RGBA pixels.
+where "filler" is the 8-bit or 16-bit number to fill with, and the location
+is either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
+you want the filler before the RGB or after. When filling an 8-bit pixel,
+the least significant 8 bits of the number are used, if a 16-bit number is
+supplied.  This transformation does not affect images that already have full
+alpha channels.  To add an opaque alpha channel, use filler=0xffff and
+PNG_FILLER_AFTER which will generate RGBA pixels.
 
 Note that png_set_filler() does not change the color type.  If you want
 to do that, you can add a true alpha channel with
@@ -2367,7 +2375,7 @@ to do that, you can add a true alpha channel with
        png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
 
 where "filler" contains the alpha value to assign to each pixel.
-This function was added in libpng-1.2.7.
+The png_set_add_alpha() function was added in libpng-1.2.7.
 
 If you are reading an image with an alpha channel, and you need the
 data as ARGB instead of the normal PNG format RGBA:
@@ -2425,9 +2433,9 @@ data for sBIT, regardless of the error_action setting.
 The default values come from the PNG file cHRM chunk if present; otherwise, the
 defaults correspond to the ITU-R recommendation 709, and also the sRGB color
 space, as recommended in the Charles Poynton's Colour FAQ,
-<http://www.poynton.com/>, in section 9:
+Copyright (c) 2006-11-28 Charles Poynton, in section 9:
 
-   <http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
+<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
 
     Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
 
@@ -4224,21 +4232,26 @@ as a wide variety of APIs to manipulate ancilliary information.
 
 To read a PNG file using the simplified API:
 
-  1) Declare a 'png_image' structure (see below) on the
-     stack and memset() it to all zero.
+  1) Declare a 'png_image' structure (see below) on the stack, set the
+     version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
+     (this is REQUIRED, your program may crash if you don't do it.)
 
   2) Call the appropriate png_image_begin_read... function.
 
-  3) Set the png_image 'format' member to the required
-     format and allocate a buffer for the image.
+  3) Set the png_image 'format' member to the required sample format.
 
-  4) Call png_image_finish_read to read the image into
-     your buffer.
+  4) Allocate a buffer for the image and, if required, the color-map.
+
+  5) Call png_image_finish_read to read the image and, if required, the
+     color-map into your buffers.
 
 There are no restrictions on the format of the PNG input itself; all valid
 color types, bit depths, and interlace methods are acceptable, and the
 input image is transformed as necessary to the requested in-memory format
-during the png_image_finish_read() step.
+during the png_image_finish_read() step.  The only caveat is that if you
+request a color-mapped image from a PNG that is full-color or makes
+complex use of an alpha channel the transformation is extremely lossy and the
+result may look terrible.
 
 To write a PNG file using the simplified API:
 
@@ -4247,34 +4260,35 @@ To write a PNG file using the simplified API:
 
   2) Initialize the members of the structure that describe the
      image, setting the 'format' member to the format of the
-     image in memory.
+     image samples.
 
   3) Call the appropriate png_image_write... function with a
-     pointer to the image to write the PNG data.
+     pointer to the image and, if necessary, the color-map to write
+     the PNG data.
 
 png_image is a structure that describes the in-memory format of an image
-when it is being read or define the in-memory format of an image that you
+when it is being read or defines the in-memory format of an image that you
 need to write.  The "png_image" structure contains the following members:
 
+   png_controlp opaque  Initialize to NULL, free with png_image_free
    png_uint_32  version Set to PNG_IMAGE_VERSION
    png_uint_32  width   Image width in pixels (columns)
    png_uint_32  height  Image height in pixels (rows)
    png_uint_32  format  Image format as defined below
    png_uint_32  flags   A bit mask containing informational flags
-   png_controlp opaque  Initialize to NULL, free with png_image_free
    png_uint_32  colormap_entries; Number of entries in the color-map
    png_uint_32  warning_or_error;
    char         message[64];
 
-In the event of an error or warning the following field warning_or_error
+In the event of an error or warning the "warning_or_error"
 field will be set to a non-zero value and the 'message' field will contain
 a '\0' terminated string with the libpng error or warning message.  If both
 warnings and an error were encountered, only the error is recorded.  If there
 are multiple warnings, only the first one is recorded.
 
-The upper 30 bits of this value are reserved; the low two bits contain
-a two bit code such that a value more than 1 indicates a failure in the API
-just called:
+The upper 30 bits of the "warning_or_error" value are reserved; the low two
+bits contain a two bit code such that a value more than 1 indicates a failure
+in the API just called:
 
    0 - no warning or error
    1 - warning
@@ -4306,64 +4320,72 @@ channels are linear.  Color channels use the RGB encoding (RGB end-points) of
 the sRGB specification.  This encoding is identified by the
 PNG_FORMAT_FLAG_LINEAR flag below.
 
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
 When an alpha channel is present it is expected to denote pixel coverage
 of the color or luminance channels and is returned as an associated alpha
 channel: the color/gray channels are scaled (pre-multiplied) by the alpha
 value.
 
-When a color-mapped image is used as a result of calling
-png_image_read_colormap or png_image_write_colormap the channels are encoded
-in the color-map and the descriptions above apply to the color-map entries.
-The image data is encoded as small integers, value 0..255, that index the
-entries in the color-map.  One integer (one byte) is stored for each pixel.
+The samples are either contained directly in the image data, between 1 and 8
+bytes per pixel according to the encoding, or are held in a color-map indexed
+by bytes in the image data.  In the case of a color-map the color-map entries
+are individual samples, encoded as above, and the image data has one byte per
+pixel to select the relevant sample from the color-map.
 
 PNG_FORMAT_*
 
 The #defines to be used in png_image::format.  Each #define identifies a
 particular layout of channel data and, if present, alpha values.  There are
-separate defines for each of the two channel encodings.
+separate defines for each of the two component encodings.
 
-A format is built up using single bit flag values.  Not all combinations are
-valid: use the bit flag values below for testing a format returned by the
-read APIs, but set formats from the derived values.
+A format is built up using single bit flag values.  All combinations are
+valid.  Formats can be built up from the flag values or you can use one of
+the predefined values below.  When testing formats always use the FORMAT_FLAG
+macros to test for individual features - future versions of the library may
+add new flags.
 
 When reading or writing color-mapped images the format should be set to the
 format of the entries in the color-map then png_image_{read,write}_colormap
 called to read or write the color-map and set the format correctly for the
 image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
 
-NOTE: libpng can be built with particular features disabled, if you see
+NOTE: libpng can be built with particular features disabled. If you see
 compiler errors because the definition of one of the following flags has been
 compiled out it is because libpng does not have the required support.  It is
 possible, however, for the libpng configuration to enable the format on just
-read or just write; in that case you may see an error at run time.  You can
-guard against this by checking for the definition of:
+read or just write; in that case you may see an error at run time.
+You can guard against this by checking for the definition of the
+appropriate "_SUPPORTED" macro, one of:
 
    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
 
-   PNG_FORMAT_FLAG_ALPHA    0x01 format with an alpha channel
-   PNG_FORMAT_FLAG_COLOR    0x02 color format: otherwise grayscale
-   PNG_FORMAT_FLAG_LINEAR   0x04 png_uint_16 channels else png_byte
-   PNG_FORMAT_FLAG_COLORMAP 0x08 libpng use only
-   PNG_FORMAT_FLAG_BGR      0x10 BGR colors, else order is RGB
-   PNG_FORMAT_FLAG_AFIRST   0x20 alpha channel comes first
+   PNG_FORMAT_FLAG_ALPHA    format with an alpha channel
+   PNG_FORMAT_FLAG_COLOR    color format: otherwise grayscale
+   PNG_FORMAT_FLAG_LINEAR   2-byte channels else 1-byte
+   PNG_FORMAT_FLAG_COLORMAP image data is color-mapped
+   PNG_FORMAT_FLAG_BGR      BGR colors, else order is RGB
+   PNG_FORMAT_FLAG_AFIRST   alpha channel comes first
 
 Supported formats are as follows.  Future versions of libpng may support more
 formats; for compatibility with older versions simply check if the format
 macro is defined using #ifdef.  These defines describe the in-memory layout
 of the components of the pixels of the image.
 
-First the single byte formats:
+First the single byte (sRGB) formats:
 
-   PNG_FORMAT_GRAY 0
-   PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
-   PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
-   PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
-   PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
-   PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
-   PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
-   PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
-   PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
+   PNG_FORMAT_GRAY
+   PNG_FORMAT_GA
+   PNG_FORMAT_AG
+   PNG_FORMAT_RGB
+   PNG_FORMAT_BGR
+   PNG_FORMAT_RGBA
+   PNG_FORMAT_ARGB
+   PNG_FORMAT_BGRA
+   PNG_FORMAT_ABGR
 
 Then the linear 2-byte formats.  When naming these "Y" is used to
 indicate a luminance (gray) channel.  The component order within the pixel
@@ -4372,22 +4394,22 @@ components in the linear format.  The components are 16-bit integers in
 the native byte order for your platform, and there is no provision for
 swapping the bytes to a different endian condition.
 
-   PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
+   PNG_FORMAT_LINEAR_Y
    PNG_FORMAT_LINEAR_Y_ALPHA
-      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
    PNG_FORMAT_LINEAR_RGB
-      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
    PNG_FORMAT_LINEAR_RGB_ALPHA
-      (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|
-      PNG_FORMAT_FLAG_ALPHA)
 
-Color-mapped formats are obtained by calling png_image_{read,write}_colormap,
-as appropriate after setting png_image::format to the format of the color-map
-to be read or written.  Applications may check the value of
-PNG_FORMAT_FLAG_COLORMAP to see if they have called the colormap API.  The
-format of the color-map may be extracted using the following macro.
+With color-mapped formats the image data is one byte for each pixel. The byte
+is an index into the color-map which is formatted as above.  To obtain a
+color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
+to one of the above definitions, or you can use one of the definitions below.
 
-   PNG_FORMAT_OF_COLORMAP(fmt) ((fmt) & ~PNG_FORMAT_FLAG_COLORMAP)
+   PNG_FORMAT_RGB_COLORMAP
+   PNG_FORMAT_BGR_COLORMAP
+   PNG_FORMAT_RGBA_COLORMAP
+   PNG_FORMAT_ARGB_COLORMAP
+   PNG_FORMAT_BGRA_COLORMAP
+   PNG_FORMAT_ABGR_COLORMAP
 
 PNG_IMAGE macros
 
@@ -4395,9 +4417,9 @@ These are convenience macros to derive information from a png_image
 structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
 actual image sample values - either the entries in the color-map or the
 pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
-for the pixels and will always return 1 after a call to
-png_image_{read,write}_colormap.  The remaining macros return information
-about the rows in the image and the complete image.
+for the pixels and will always return 1 for color-mapped formats.  The
+remaining macros return information about the rows in the image and the
+complete image.
 
 NOTE: All the macros that take a png_image::format parameter are compile time
 constants if the format parameter is, itself, a constant.  Therefore these
@@ -4405,46 +4427,39 @@ macros can be used in array declarations and case labels where required.
 Similarly the macros are also pre-processor constants (sizeof is not used) so
 they can be used in #if tests.
 
-First the information about the samples.
-
   PNG_IMAGE_SAMPLE_CHANNELS(fmt)
     Returns the total number of channels in a given format: 1..4
 
   PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)
     Returns the size in bytes of a single component of a pixel or color-map
-    entry (as appropriate) in the image.
+    entry (as appropriate) in the image: 1 or 2.
 
   PNG_IMAGE_SAMPLE_SIZE(fmt)
     This is the size of the sample data for one sample.  If the image is
     color-mapped it is the size of one color-map entry (and image pixels are
     one byte in size), otherwise it is the size of one image pixel.
 
+  PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)
+    The maximum size of the color-map required by the format expressed in a
+    count of components.  This can be used to compile-time allocate a
+    color-map:
+
+    png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+
+    png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+
+    Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+    information from one of the png_image_begin_read_ APIs and dynamically
+    allocate the required memory.
+
   PNG_IMAGE_COLORMAP_SIZE(fmt)
    The size of the color-map required by the format; this is the size of the
-   color-map buffer passed to the png_image_{read,write}_colormap APIs, it is
+   color-map buffer passed to the png_image_{read,write}_colormap APIs. It is
    a fixed number determined by the format so can easily be allocated on the
    stack if necessary.
 
-#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
-   (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
-   /* The maximum size of the color-map required by the format expressed in a
-    * count of components.  This can be used to compile-time allocate a
-    * color-map:
-    *
-    * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
-    *
-    * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
-    *
-    * Alternatively, use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
-    * information from one of the png_image_begin_read_ APIs and dynamically
-    * allocate the required memory.
-    */
-
-
 Corresponding information about the pixels
 
-  PNG_IMAGE_PIXEL_(test,fmt)
-
   PNG_IMAGE_PIXEL_CHANNELS(fmt)
    The number of separate channels (components) in a pixel; 1 for a
    color-mapped image.
@@ -4470,19 +4485,54 @@ Information about the whole row, or whole image
    to start the next row on a 4-byte boundary.
 
   PNG_IMAGE_BUFFER_SIZE(image, row_stride)
-    Returns the size, in bytes, of an image buffer given a png_image and a row
-    stride - the number of components to leave space for in each row.  This
-    macro takes care of multiplying row_stride by PNG_IMAGE_PIXEL_COMONENT_SIZE
-    when the image has 2-byte components.
+   Return the size, in bytes, of an image buffer given a png_image and a row
+   stride - the number of components to leave space for in each row.
+
+  PNG_IMAGE_SIZE(image)
+   Return the size, in bytes, of the image in memory given just a png_image;
+   the row stride is the minimum stride required for the image.
+
+  PNG_IMAGE_COLORMAP_SIZE(image)
+   Return the size, in bytes, of the color-map of this image.  If the image
+   format is not a color-map format this will return a size sufficient for
+   256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
+   you don't want to allocate a color-map in this case.
+
+PNG_IMAGE_FLAG_*
+
+Flags containing additional information about the image are held in
+the 'flags' field of png_image.
 
   PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
     This indicates the the RGB values of the in-memory bitmap do not
     correspond to the red, green and blue end-points defined by sRGB.
 
-  PNG_IMAGE_FLAG_COLORMAP == 0x02
-    The PNG is color-mapped.  If this flag is set png_image_read_colormap
-    can be used without further loss of image information.  If it is not set
-    png_image_read_colormap will cause significant loss if the image has any
+  PNG_IMAGE_FLAG_FAST == 0x02
+   On write emphasise speed over compression; the resultant PNG file will be
+   larger but will be produced significantly faster, particular for large
+   images.  Do not use this option for images which will be distributed, only
+   used it when producing intermediate files that will be read back in
+   repeatedly.  For a typical 24-bit image the option will double the read
+   speed at the cost of increasing the image size by 25%, however for many
+   more compressible images the PNG file can be 10 times larger with only a
+   slight speed gain.
+
+  PNG_IMAGE_FLAG_16BIT_sRGB == 0x04
+    On read if the image is a 16-bit per component image and there is no gAMA
+    or sRGB chunk assume that the components are sRGB encoded.  Notice that
+    images output by the simplified API always have gamma information; setting
+    this flag only affects the interpretation of 16-bit images from an
+    external source.  It is recommended that the application expose this flag
+    to the user; the user can normally easily recognize the difference between
+    linear and sRGB encoding.  This flag has no effect on write - the data
+    passed to the write APIs must have the correct encoding (as defined
+    above.)
+
+    If the flag is not set (the default) input 16-bit per component data is
+    assumed to be linear.
+
+    NOTE: the flag can only be set after the png_image_begin_read_ call,
+    because that call initializes the 'flags' field.
 
 READ APIs
 
@@ -5364,7 +5414,7 @@ limits are now
    png_user_chunk_malloc_max 0 (unlimited) 8,000,000
 
 The png_set_option() function (and the "options" member of the png struct) was
-added to libpng-1.5.15.
+added to libpng-1.5.15, with option PNG_ARM_NEON.
 
 The library now supports a complete fixed point implementation and can
 thus be used on systems that have no floating point support or very
@@ -5506,9 +5556,9 @@ The signatures of many exported functions were changed, such that
    png_infop became png_inforp or png_const_inforp
 where "rp" indicates a "restricted pointer".
 
-The support for FAR/far types has been eliminated and the definition of
-png_alloc_size_t is now controlled by a flag so that 'small size_t' systems
-can select it if necessary.
+Dropped support for 16-bit platforms. The support for FAR/far types has
+been eliminated and the definition of png_alloc_size_t is now controlled
+by a flag so that 'small size_t' systems can select it if necessary.
 
 Error detection in some chunks has improved; in particular the iCCP chunk
 reader now does pretty complete validation of the basic format.  Some bad
@@ -5600,6 +5650,11 @@ It can be set for testing debug or beta builds to ensure that they will compile
 when the build type is switched to RC or STABLE. In essence this overrides the
 PNG_LIBPNG_BUILD_BASE_TYPE definition which is not directly user controllable.
 
+Starting with libpng-1.6.19, attempting to set an over-length PLTE chunk
+is an error. Previously this requirement of the PNG specification was not
+enforced, and the palette was always limited to 256 entries. An over-length
+PLTE chunk found in an input PNG is silently truncated.
+
 .SH XIII.  Detecting libpng
 
 The png_get_io_ptr() function has been present since libpng-0.88, has never
@@ -5753,10 +5808,12 @@ We prefer #ifdef and #ifndef to #if defined() and #if !defined()
 when there is only one macro being tested.  We always use parentheses
 with "defined".
 
-We prefer to express integers that are used as bit masks in hex format,
-with an even number of lower-case hex digits (e.g., 0x00, 0xff, 0x0100).
+We express integer constants that are used as bit masks in hex format,
+with an even number of lower-case hex digits, and to make them unsigned
+(e.g., 0x00U, 0xffU, 0x0100U) and long if they are greater than 0x7fff
+(e.g., 0xffffUL).
 
-We prefer to use underscores in variable names rather than camelCase, except
+We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.
 
 We prefer "if (something != 0)" and "if (something == 0)"
@@ -5770,13 +5827,11 @@ Other rules can be inferred by inspecting the libpng source.
 
 .SH XVI. Y2K Compliance in libpng
 
-July 23, 2015
-
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.18 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.19 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -5838,202 +5893,47 @@ the first widely used release:
  source             png.h  png.h  shared-lib
  version            string   int  version
  -------            ------  ----- ----------
- 0.89c ("beta 3")  0.89       89  1.0.89
- 0.90  ("beta 4")  0.90       90  0.90
- 0.95  ("beta 5")  0.95       95  0.95
- 0.96  ("beta 6")  0.96       96  0.96
- 0.97b ("beta 7")  1.00.97    97  1.0.1
- 0.97c             0.97       97  2.0.97
- 0.98              0.98       98  2.0.98
- 0.99              0.99       98  2.0.99
- 0.99a-m           0.99       99  2.0.99
- 1.00              1.00      100  2.1.0
- 1.0.0             1.0.0     100  2.1.0
- 1.0.0   (from here on, the  100  2.1.0
- 1.0.1    png.h string is  10001  2.1.0
- 1.0.1a-e identical to the 10002  from here on, the
- 1.0.2    source version)  10002  shared library is 2.V
- 1.0.2a-b                  10003  where V is the source
- 1.0.1                     10001  code version except as
- 1.0.1a-e                  10002  2.1.0.1a-e   noted.
- 1.0.2                     10002  2.1.0.2
- 1.0.2a-b                  10003  2.1.0.2a-b
- 1.0.3                     10003  2.1.0.3
- 1.0.3a-d                  10004  2.1.0.3a-d
- 1.0.4                     10004  2.1.0.4
- 1.0.4a-f                  10005  2.1.0.4a-f
- 1.0.5 (+ 2 patches)       10005  2.1.0.5
- 1.0.5a-d                  10006  2.1.0.5a-d
- 1.0.5e-r                  10100  2.1.0.5e-r
- 1.0.5s-v                  10006  2.1.0.5s-v
- 1.0.6 (+ 3 patches)       10006  2.1.0.6
- 1.0.6d-g                  10007  2.1.0.6d-g
- 1.0.6h                    10007  10.6h
- 1.0.6i                    10007  10.6i
- 1.0.6j                    10007  2.1.0.6j
- 1.0.7beta11-14    DLLNUM  10007  2.1.0.7beta11-14
- 1.0.7beta15-18       1    10007  2.1.0.7beta15-18
- 1.0.7rc1-2           1    10007  2.1.0.7rc1-2
- 1.0.7                1    10007  2.1.0.7
- 1.0.8beta1-4         1    10008  2.1.0.8beta1-4
- 1.0.8rc1             1    10008  2.1.0.8rc1
- 1.0.8                1    10008  2.1.0.8
- 1.0.9beta1-6         1    10009  2.1.0.9beta1-6
- 1.0.9rc1             1    10009  2.1.0.9rc1
- 1.0.9beta7-10        1    10009  2.1.0.9beta7-10
- 1.0.9rc2             1    10009  2.1.0.9rc2
- 1.0.9                1    10009  2.1.0.9
- 1.0.10beta1          1    10010  2.1.0.10beta1
- 1.0.10rc1            1    10010  2.1.0.10rc1
- 1.0.10               1    10010  2.1.0.10
- 1.0.11beta1-3        1    10011  2.1.0.11beta1-3
- 1.0.11rc1            1    10011  2.1.0.11rc1
- 1.0.11               1    10011  2.1.0.11
- 1.0.12beta1-2        2    10012  2.1.0.12beta1-2
- 1.0.12rc1            2    10012  2.1.0.12rc1
- 1.0.12               2    10012  2.1.0.12
- 1.1.0a-f             -    10100  2.1.1.0a-f abandoned
- 1.2.0beta1-2         2    10200  2.1.2.0beta1-2
- 1.2.0beta3-5         3    10200  3.1.2.0beta3-5
- 1.2.0rc1             3    10200  3.1.2.0rc1
- 1.2.0                3    10200  3.1.2.0
- 1.2.1beta-4          3    10201  3.1.2.1beta1-4
- 1.2.1rc1-2           3    10201  3.1.2.1rc1-2
- 1.2.1                3    10201  3.1.2.1
- 1.2.2beta1-6        12    10202  12.so.0.1.2.2beta1-6
- 1.0.13beta1         10    10013  10.so.0.1.0.13beta1
- 1.0.13rc1           10    10013  10.so.0.1.0.13rc1
- 1.2.2rc1            12    10202  12.so.0.1.2.2rc1
- 1.0.13              10    10013  10.so.0.1.0.13
- 1.2.2               12    10202  12.so.0.1.2.2
- 1.2.3rc1-6          12    10203  12.so.0.1.2.3rc1-6
- 1.2.3               12    10203  12.so.0.1.2.3
- 1.2.4beta1-3        13    10204  12.so.0.1.2.4beta1-3
- 1.2.4rc1            13    10204  12.so.0.1.2.4rc1
- 1.0.14              10    10014  10.so.0.1.0.14
- 1.2.4               13    10204  12.so.0.1.2.4
- 1.2.5beta1-2        13    10205  12.so.0.1.2.5beta1-2
- 1.0.15rc1           10    10015  10.so.0.1.0.15rc1
- 1.0.15              10    10015  10.so.0.1.0.15
- 1.2.5               13    10205  12.so.0.1.2.5
- 1.2.6beta1-4        13    10206  12.so.0.1.2.6beta1-4
- 1.2.6rc1-5          13    10206  12.so.0.1.2.6rc1-5
- 1.0.16              10    10016  10.so.0.1.0.16
- 1.2.6               13    10206  12.so.0.1.2.6
- 1.2.7beta1-2        13    10207  12.so.0.1.2.7beta1-2
- 1.0.17rc1           10    10017  12.so.0.1.0.17rc1
- 1.2.7rc1            13    10207  12.so.0.1.2.7rc1
- 1.0.17              10    10017  12.so.0.1.0.17
- 1.2.7               13    10207  12.so.0.1.2.7
- 1.2.8beta1-5        13    10208  12.so.0.1.2.8beta1-5
- 1.0.18rc1-5         10    10018  12.so.0.1.0.18rc1-5
- 1.2.8rc1-5          13    10208  12.so.0.1.2.8rc1-5
- 1.0.18              10    10018  12.so.0.1.0.18
- 1.2.8               13    10208  12.so.0.1.2.8
- 1.2.9beta1-3        13    10209  12.so.0.1.2.9beta1-3
- 1.2.9beta4-11       13    10209  12.so.0.9[.0]
- 1.2.9rc1            13    10209  12.so.0.9[.0]
- 1.2.9               13    10209  12.so.0.9[.0]
- 1.2.10beta1-7       13    10210  12.so.0.10[.0]
- 1.2.10rc1-2         13    10210  12.so.0.10[.0]
- 1.2.10              13    10210  12.so.0.10[.0]
- 1.4.0beta1-6        14    10400  14.so.0.0[.0]
- 1.2.11beta1-4       13    10210  12.so.0.11[.0]
- 1.4.0beta7-8        14    10400  14.so.0.0[.0]
- 1.2.11              13    10211  12.so.0.11[.0]
- 1.2.12              13    10212  12.so.0.12[.0]
- 1.4.0beta9-14       14    10400  14.so.0.0[.0]
- 1.2.13              13    10213  12.so.0.13[.0]
- 1.4.0beta15-36      14    10400  14.so.0.0[.0]
- 1.4.0beta37-87      14    10400  14.so.14.0[.0]
- 1.4.0rc01           14    10400  14.so.14.0[.0]
- 1.4.0beta88-109     14    10400  14.so.14.0[.0]
- 1.4.0rc02-08        14    10400  14.so.14.0[.0]
- 1.4.0               14    10400  14.so.14.0[.0]
- 1.4.1beta01-03      14    10401  14.so.14.1[.0]
- 1.4.1rc01           14    10401  14.so.14.1[.0]
- 1.4.1beta04-12      14    10401  14.so.14.1[.0]
- 1.4.1               14    10401  14.so.14.1[.0]
- 1.4.2               14    10402  14.so.14.2[.0]
- 1.4.3               14    10403  14.so.14.3[.0]
- 1.4.4               14    10404  14.so.14.4[.0]
- 1.5.0beta01-58      15    10500  15.so.15.0[.0]
- 1.5.0rc01-07        15    10500  15.so.15.0[.0]
- 1.5.0               15    10500  15.so.15.0[.0]
- 1.5.1beta01-11      15    10501  15.so.15.1[.0]
- 1.5.1rc01-02        15    10501  15.so.15.1[.0]
- 1.5.1               15    10501  15.so.15.1[.0]
- 1.5.2beta01-03      15    10502  15.so.15.2[.0]
- 1.5.2rc01-03        15    10502  15.so.15.2[.0]
- 1.5.2               15    10502  15.so.15.2[.0]
- 1.5.3beta01-10      15    10503  15.so.15.3[.0]
- 1.5.3rc01-02        15    10503  15.so.15.3[.0]
- 1.5.3beta11         15    10503  15.so.15.3[.0]
- 1.5.3 [omitted]
- 1.5.4beta01-08      15    10504  15.so.15.4[.0]
- 1.5.4rc01           15    10504  15.so.15.4[.0]
- 1.5.4               15    10504  15.so.15.4[.0]
- 1.5.5beta01-08      15    10505  15.so.15.5[.0]
- 1.5.5rc01           15    10505  15.so.15.5[.0]
- 1.5.5               15    10505  15.so.15.5[.0]
- 1.5.6beta01-07      15    10506  15.so.15.6[.0]
- 1.5.6rc01-03        15    10506  15.so.15.6[.0]
- 1.5.6               15    10506  15.so.15.6[.0]
- 1.5.7beta01-05      15    10507  15.so.15.7[.0]
- 1.5.7rc01-03        15    10507  15.so.15.7[.0]
- 1.5.7               15    10507  15.so.15.7[.0]
- 1.6.0beta01-40      16    10600  16.so.16.0[.0]
- 1.6.0rc01-08        16    10600  16.so.16.0[.0]
- 1.6.0               16    10600  16.so.16.0[.0]
- 1.6.1beta01-09      16    10601  16.so.16.1[.0]
- 1.6.1rc01           16    10601  16.so.16.1[.0]
- 1.6.1               16    10601  16.so.16.1[.0]
- 1.6.2beta01         16    10602  16.so.16.2[.0]
- 1.6.2rc01-06        16    10602  16.so.16.2[.0]
- 1.6.2               16    10602  16.so.16.2[.0]
- 1.6.3beta01-11      16    10603  16.so.16.3[.0]
- 1.6.3rc01           16    10603  16.so.16.3[.0]
- 1.6.3               16    10603  16.so.16.3[.0]
- 1.6.4beta01-02      16    10604  16.so.16.4[.0]
- 1.6.4rc01           16    10604  16.so.16.4[.0]
- 1.6.4               16    10604  16.so.16.4[.0]
- 1.6.5               16    10605  16.so.16.5[.0]
- 1.6.6               16    10606  16.so.16.6[.0]
- 1.6.7beta01-04      16    10607  16.so.16.7[.0]
- 1.6.7rc01-02        16    10607  16.so.16.7[.0]
- 1.6.7               16    10607  16.so.16.7[.0]
- 1.6.8beta01-02      16    10608  16.so.16.8[.0]
- 1.6.8rc01-02        16    10608  16.so.16.8[.0]
- 1.6.8               16    10608  16.so.16.8[.0]
- 1.6.9beta01-04      16    10609  16.so.16.9[.0]
- 1.6.9rc01-02        16    10609  16.so.16.9[.0]
- 1.6.9               16    10609  16.so.16.9[.0]
- 1.6.10beta01-03     16    10610  16.so.16.10[.0]
- 1.6.10rc01-03       16    10610  16.so.16.10[.0]
- 1.6.10              16    10610  16.so.16.10[.0]
- 1.6.11beta01-06     16    10611  16.so.16.11[.0]
- 1.6.11rc01-02       16    10611  16.so.16.11[.0]
- 1.6.11              16    10611  16.so.16.11[.0]
- 1.6.12rc01          16    10612  16.so.16.12[.0]
- 1.6.12              16    10612  16.so.16.12[.0]
- 1.6.13beta01-04     16    10613  16.so.16.13[.0]
- 1.6.13rc01-02       16    10613  16.so.16.13[.0]
- 1.6.13              16    10613  16.so.16.13[.0]
- 1.6.14beta01-07     16    10614  16.so.16.14[.0]
- 1.6.14rc01-02       16    10614  16.so.16.14[.0]
- 1.6.14              16    10614  16.so.16.14[.0]
- 1.6.15beta01-08     16    10615  16.so.16.15[.0]
- 1.6.15rc01-03       16    10615  16.so.16.15[.0]
- 1.6.15              16    10615  16.so.16.15[.0]
- 1.6.16beta01-03     16    10616  16.so.16.16[.0]
- 1.6.16rc01-02       16    10616  16.so.16.16[.0]
- 1.6.16              16    10616  16.so.16.16[.0]
- 1.6.17beta01-06     16    10617  16.so.16.17[.0]
- 1.6.17rc01-06       16    10617  16.so.16.17[.0]
- 1.6.17              16    10617  16.so.16.17[.0]
- 1.6.18beta01-09     16    10618  16.so.16.18[.0]
- 1.6.18rc01-03       16    10618  16.so.16.18[.0]
- 1.6.18              16    10618  16.so.16.18[.0]
+ 0.89c "1.0 beta 3"     0.89      89  1.0.89
+ 0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
+ 0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
+ 0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
+ 0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
+ 0.97c                  0.97      97  2.0.97
+ 0.98                   0.98      98  2.0.98
+ 0.99                   0.99      98  2.0.99
+ 0.99a-m                0.99      99  2.0.99
+ 1.00                   1.00     100  2.1.0 [100 should be 10000]
+ 1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
+ 1.0.1       png.h string is   10001  2.1.0
+ 1.0.1a-e    identical to the  10002  from here on, the shared library
+ 1.0.2       source version)   10002  is 2.V where V is the source code
+ 1.0.2a-b                      10003  version, except as noted.
+ 1.0.3                         10003
+ 1.0.3a-d                      10004
+ 1.0.4                         10004
+ 1.0.4a-f                      10005
+ 1.0.5 (+ 2 patches)           10005
+ 1.0.5a-d                      10006
+ 1.0.5e-r                      10100 (not source compatible)
+ 1.0.5s-v                      10006 (not binary compatible)
+ 1.0.6 (+ 3 patches)           10006 (still binary incompatible)
+ 1.0.6d-f                      10007 (still binary incompatible)
+ 1.0.6g                        10007
+ 1.0.6h                        10007  10.6h (testing xy.z so-numbering)
+ 1.0.6i                        10007  10.6i
+ 1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
+ 1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
+ 1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
+ 1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
+ 1.0.7                    1    10007  (still compatible)
+ ...
+ 1.0.19                  10    10019  10.so.0.19[.0]
+ ...
+ 1.2.53                  13    10253  12.so.0.53[.0]
+ ...
+ 1.5.23                  15    10523  15.so.15.23[.0]
+ ...
+ 1.6.19                  16    10619  16.so.16.19[.0]
 
 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6043,11 +5943,10 @@ for applications, is an unsigned integer of the form xyyzz corresponding
 to the source version x.y.z (leading zeros in y and z).  Beta versions
 were given the previous public release number plus a letter, until
 version 1.0.6j; from then on they were given the upcoming public
-release number plus "betaNN" or "rcN".
+release number plus "betaNN" or "rcNN".
 
 .SH "SEE ALSO"
-.BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
-
+.IR libpngpf(3) ", " png(5)
 .LP
 .IR libpng :
 .IP
@@ -6070,7 +5969,7 @@ ftp://ftp.info-zip.org/pub/infozip/zlib
 .I libpng
 or at
 .br
-ftp://ds.internic.net/rfc/rfc2083.txt
+ftp://ftp.rfc-editor.org:/in-notes/rfc2083.txt
 .br
 or (as a W3C Recommendation) at
 .br
@@ -6090,7 +5989,7 @@ possible without all of you.
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.6.18 - July 23, 2015:
+Libpng version 1.6.19 - November 12, 2015:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -6102,21 +6001,24 @@ png-mng-implement at lists.sourceforge.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe).
 
-.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+.SH NOTICES:
 
-(This copy of the libpng notices is provided for your convenience.  In case of
+This copy of the libpng notices is provided for your convenience.  In case of
 any discrepancy between this copy and the notices in the file png.h that is
-included in the libpng distribution, the latter shall prevail.)
+included in the libpng distribution, the latter shall prevail.
+
+COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
 
 If you modify libpng you may insert additional notices immediately following
 this sentence.
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000, through 1.6.18, July 23, 2015, are
-Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, and are
-distributed according to the same disclaimer and license as libpng-1.0.6
-with the following individuals added to the list of Contributing Authors:
+libpng versions 1.0.7, July 1, 2000, through 1.6.19, November 12, 2015, are
+Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+derived from libpng-1.0.6, and are distributed according to the same
+disclaimer and license as libpng-1.0.6 with the following individuals
+added to the list of Contributing Authors:
 
    Simon-Pierre Cadieux
    Eric S. Raymond
@@ -6135,18 +6037,20 @@ and with the following additions to the disclaimer:
    the user.
 
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
-Copyright (c) 1998-2000 Glenn Randers-Pehrson, and are distributed according
-to the same disclaimer and license as libpng-0.96, with the following
-individuals added to the list of Contributing Authors:
+Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+libpng-0.96, and are distributed according to the same disclaimer and
+license as libpng-0.96, with the following individuals added to the list
+of Contributing Authors:
 
    Tom Lane
    Glenn Randers-Pehrson
    Willem van Schaik
 
 libpng versions 0.89, June 1996, through 0.96, May 1997, are
-Copyright (c) 1996-1997 Andreas Dilger, and are
-distributed according to the same disclaimer and license as libpng-0.88,
-with the following individuals added to the list of Contributing Authors:
+Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+and are distributed according to the same disclaimer and license as
+libpng-0.88, with the following individuals added to the list of
+Contributing Authors:
 
    John Bowler
    Kevin Bracey
@@ -6193,6 +6097,8 @@ supporting the PNG file format in commercial products.  If you use this
 source code in a product, acknowledgment is not required but would be
 appreciated.
 
+END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
+
 A "png_get_copyright" function is available, for convenient use in "about"
 boxes and the like:
 
@@ -6207,7 +6113,7 @@ the additional disclaimers inserted at version 1.0.7.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-July 23, 2015
+November 12, 2015
 
 .\" end of man page
 
diff --git a/libpngpf.3 b/libpngpf.3
index f5511dd2a..00cf487d2 100644
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "July 23, 2015"
+.TH LIBPNGPF 3 "November 12, 2015"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.18
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.19
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
diff --git a/png.5 b/png.5
index 37a8525c6..1e515b7f5 100644
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "July 23, 2015"
+.TH PNG 5 "November 12, 2015"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
@@ -27,7 +27,7 @@ PNG specification (second edition), November 2003:
 PNG 1.2 specification, July 1999:
 .IP
 .br
-http://www.libpng.org/pub/png
+http://png-mng.sourceforge.net/pub/png/spec/1.2/
 .LP
 PNG 1.0 specification, October 1996:
 .IP
@@ -39,7 +39,7 @@ ftp://ds.internic.net/rfc/rfc2083.txt
 .br
 or (as a W3C Recommendation) at
 .br
-http://www.w3.org/TR/REC-png.html
+http://www.w3.org/TR/REC-png-961001
 .SH AUTHORS
 This man page: Glenn Randers-Pehrson
 .LP
diff --git a/png.c b/png.c
index f6e353ace..6fcfad72e 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -14,7 +14,7 @@
 #include "pngpriv.h"
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_18 Your_png_h_is_not_version_1_6_18;
+typedef png_libpng_version_1_6_19 Your_png_h_is_not_version_1_6_19;
 
 /* Tells libpng that we have already handled the first "num_bytes" bytes
  * of the PNG file signature.  If the PNG data is embedded into another
@@ -26,15 +26,20 @@ typedef png_libpng_version_1_6_18 Your_png_h_is_not_version_1_6_18;
 void PNGAPI
 png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
 {
+   unsigned int nb = (unsigned int)num_bytes;
+
    png_debug(1, "in png_set_sig_bytes");
 
    if (png_ptr == NULL)
       return;
 
-   if (num_bytes > 8)
+   if (num_bytes < 0)
+      nb = 0;
+
+   if (nb > 8)
       png_error(png_ptr, "Too many bytes for PNG signature");
 
-   png_ptr->sig_bytes = (png_byte)((num_bytes < 0 ? 0 : num_bytes) & 0xff);
+   png_ptr->sig_bytes = (png_byte)nb;
 }
 
 /* Checks whether the supplied bytes match the PNG signature.  We allow
@@ -413,6 +418,8 @@ png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
       free(info_ptr);
       info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
          (sizeof *info_ptr)));
+      if (info_ptr == NULL)
+         return;
       *ptr_ptr = info_ptr;
    }
 
@@ -664,19 +671,20 @@ png_init_io(png_structrp png_ptr, png_FILE_p fp)
 #  endif
 
 #  ifdef PNG_SAVE_INT_32_SUPPORTED
-/* The png_save_int_32 function assumes integers are stored in two's
- * complement format.  If this isn't the case, then this routine needs to
- * be modified to write data in two's complement format.  Note that,
- * the following works correctly even if png_int_32 has more than 32 bits
- * (compare the more complex code required on read for sign extension.)
+/* PNG signed integers are saved in 32-bit 2's complement format.  ANSI C-90
+ * defines a cast of a signed integer to an unsigned integer either to preserve
+ * the value, if it is positive, or to calculate:
+ *
+ *     (UNSIGNED_MAX+1) + integer
+ *
+ * Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
+ * negative integral value is added the result will be an unsigned value
+ * correspnding to the 2's complement representation.
  */
 void PNGAPI
 png_save_int_32(png_bytep buf, png_int_32 i)
 {
-   buf[0] = (png_byte)((i >> 24) & 0xff);
-   buf[1] = (png_byte)((i >> 16) & 0xff);
-   buf[2] = (png_byte)((i >> 8) & 0xff);
-   buf[3] = (png_byte)(i & 0xff);
+   png_save_uint_32(buf, i);
 }
 #  endif
 
@@ -722,6 +730,7 @@ png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
       APPEND(':');
       APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
       APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
+      PNG_UNUSED (pos)
 
 #     undef APPEND
 #     undef APPEND_NUMBER
@@ -766,13 +775,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-      "libpng version 1.6.18 - July 23, 2015" PNG_STRING_NEWLINE \
+      "libpng version 1.6.19 - November 12, 2015" PNG_STRING_NEWLINE \
       "Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
       "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
       "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
       PNG_STRING_NEWLINE;
 #  else
-   return "libpng version 1.6.18 - July 23, 2015\
+   return "libpng version 1.6.19 - November 12, 2015\
       Copyright (c) 1998-2015 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -1703,7 +1712,6 @@ png_colorspace_set_chromaticities(png_const_structrp png_ptr,
           */
          colorspace->flags |= PNG_COLORSPACE_INVALID;
          png_error(png_ptr, "internal error checking chromaticities");
-         break;
    }
 
    return 0; /* failed */
@@ -1731,7 +1739,6 @@ png_colorspace_set_endpoints(png_const_structrp png_ptr,
       default:
          colorspace->flags |= PNG_COLORSPACE_INVALID;
          png_error(png_ptr, "internal error checking chromaticities");
-         break;
    }
 
    return 0; /* failed */
@@ -2057,8 +2064,8 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
    temp = png_get_uint_32(profile+12); /* profile/device class */
    switch (temp)
    {
-      case 0x73636E72: /* 'scnr' */
-      case 0x6D6E7472: /* 'mntr' */
+      case 0x73636e72: /* 'scnr' */
+      case 0x6d6e7472: /* 'mntr' */
       case 0x70727472: /* 'prtr' */
       case 0x73706163: /* 'spac' */
          /* All supported */
@@ -2069,7 +2076,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
          return png_icc_profile_error(png_ptr, colorspace, name, temp,
             "invalid embedded Abstract ICC profile");
 
-      case 0x6C696E6B: /* 'link' */
+      case 0x6c696e6b: /* 'link' */
          /* DeviceLink profiles cannot be interpreted in a non-device specific
           * fashion, if an app uses the AToB0Tag in the profile the results are
           * undefined unless the result is sent to the intended device,
@@ -2079,7 +2086,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
          return png_icc_profile_error(png_ptr, colorspace, name, temp,
             "unexpected DeviceLink ICC profile class");
 
-      case 0x6E6D636C: /* 'nmcl' */
+      case 0x6e6d636c: /* 'nmcl' */
          /* A NamedColor profile is also device specific, however it doesn't
           * contain an AToB0 tag that is open to misinterpretation.  Almost
           * certainly it will fail the tests below.
@@ -2105,8 +2112,8 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
    temp = png_get_uint_32(profile+20);
    switch (temp)
    {
-      case 0x58595A20: /* 'XYZ ' */
-      case 0x4C616220: /* 'Lab ' */
+      case 0x58595a20: /* 'XYZ ' */
+      case 0x4c616220: /* 'Lab ' */
          break;
 
       default:
@@ -2276,7 +2283,7 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
          }
 
          /* Length *and* intent must match */
-         if (length == png_sRGB_checks[i].length &&
+         if (length == (png_uint_32) png_sRGB_checks[i].length &&
             intent == (png_uint_32) png_sRGB_checks[i].intent)
          {
             /* Now calculate the adler32 if not done already. */
@@ -3144,7 +3151,7 @@ png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
 
       /* Avoid overflow here on the minimum integer. */
       if (fp < 0)
-         *ascii++ = 45, --size, num = -fp;
+         *ascii++ = 45, num = -fp;
       else
          num = fp;
 
@@ -3675,7 +3682,7 @@ png_exp(png_fixed_point x)
    if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
    {
       /* Obtain a 4-bit approximation */
-      png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf];
+      png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f];
 
       /* Incorporate the low 12 bits - these decrease the returned value by
        * multiplying by a number less than 1 if the bit is set.  The multiplier
diff --git a/png.h b/png.h
index f2013cf75..c83051b1c 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.6.18, July 23, 2015
+ * libpng version 1.6.19, November 12, 2015
  *
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,234 +12,8 @@
  * Authors and maintainers:
  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.18, July 23, 2015: Glenn
+ *   libpng versions 0.97, January 1998, through 1.6.19, November 12, 2015: Glenn
  *   See also "Contributing Authors", below.
- *
- * Note about libpng version numbers:
- *
- *   Due to various miscommunications, unforeseen code incompatibilities
- *   and occasional factors outside the authors' control, version numbering
- *   on the library has not always been consistent and straightforward.
- *   The following table summarizes matters since version 0.89c, which was
- *   the first widely used release:
- *
- *    source                 png.h  png.h  shared-lib
- *    version                string   int  version
- *    -------                ------ -----  ----------
- *    0.89c "1.0 beta 3"     0.89      89  1.0.89
- *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
- *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
- *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
- *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
- *    0.97c                  0.97      97  2.0.97
- *    0.98                   0.98      98  2.0.98
- *    0.99                   0.99      98  2.0.99
- *    0.99a-m                0.99      99  2.0.99
- *    1.00                   1.00     100  2.1.0 [100 should be 10000]
- *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
- *    1.0.1       png.h string is   10001  2.1.0
- *    1.0.1a-e    identical to the  10002  from here on, the shared library
- *    1.0.2       source version)   10002  is 2.V where V is the source code
- *    1.0.2a-b                      10003  version, except as noted.
- *    1.0.3                         10003
- *    1.0.3a-d                      10004
- *    1.0.4                         10004
- *    1.0.4a-f                      10005
- *    1.0.5 (+ 2 patches)           10005
- *    1.0.5a-d                      10006
- *    1.0.5e-r                      10100 (not source compatible)
- *    1.0.5s-v                      10006 (not binary compatible)
- *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
- *    1.0.6d-f                      10007 (still binary incompatible)
- *    1.0.6g                        10007
- *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
- *    1.0.6i                        10007  10.6i
- *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
- *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
- *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
- *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
- *    1.0.7                    1    10007  (still compatible)
- *    1.0.8beta1-4             1    10008  2.1.0.8beta1-4
- *    1.0.8rc1                 1    10008  2.1.0.8rc1
- *    1.0.8                    1    10008  2.1.0.8
- *    1.0.9beta1-6             1    10009  2.1.0.9beta1-6
- *    1.0.9rc1                 1    10009  2.1.0.9rc1
- *    1.0.9beta7-10            1    10009  2.1.0.9beta7-10
- *    1.0.9rc2                 1    10009  2.1.0.9rc2
- *    1.0.9                    1    10009  2.1.0.9
- *    1.0.10beta1              1    10010  2.1.0.10beta1
- *    1.0.10rc1                1    10010  2.1.0.10rc1
- *    1.0.10                   1    10010  2.1.0.10
- *    1.0.11beta1-3            1    10011  2.1.0.11beta1-3
- *    1.0.11rc1                1    10011  2.1.0.11rc1
- *    1.0.11                   1    10011  2.1.0.11
- *    1.0.12beta1-2            2    10012  2.1.0.12beta1-2
- *    1.0.12rc1                2    10012  2.1.0.12rc1
- *    1.0.12                   2    10012  2.1.0.12
- *    1.1.0a-f                 -    10100  2.1.1.0a-f (branch abandoned)
- *    1.2.0beta1-2             2    10200  2.1.2.0beta1-2
- *    1.2.0beta3-5             3    10200  3.1.2.0beta3-5
- *    1.2.0rc1                 3    10200  3.1.2.0rc1
- *    1.2.0                    3    10200  3.1.2.0
- *    1.2.1beta1-4             3    10201  3.1.2.1beta1-4
- *    1.2.1rc1-2               3    10201  3.1.2.1rc1-2
- *    1.2.1                    3    10201  3.1.2.1
- *    1.2.2beta1-6            12    10202  12.so.0.1.2.2beta1-6
- *    1.0.13beta1             10    10013  10.so.0.1.0.13beta1
- *    1.0.13rc1               10    10013  10.so.0.1.0.13rc1
- *    1.2.2rc1                12    10202  12.so.0.1.2.2rc1
- *    1.0.13                  10    10013  10.so.0.1.0.13
- *    1.2.2                   12    10202  12.so.0.1.2.2
- *    1.2.3rc1-6              12    10203  12.so.0.1.2.3rc1-6
- *    1.2.3                   12    10203  12.so.0.1.2.3
- *    1.2.4beta1-3            13    10204  12.so.0.1.2.4beta1-3
- *    1.0.14rc1               13    10014  10.so.0.1.0.14rc1
- *    1.2.4rc1                13    10204  12.so.0.1.2.4rc1
- *    1.0.14                  10    10014  10.so.0.1.0.14
- *    1.2.4                   13    10204  12.so.0.1.2.4
- *    1.2.5beta1-2            13    10205  12.so.0.1.2.5beta1-2
- *    1.0.15rc1-3             10    10015  10.so.0.1.0.15rc1-3
- *    1.2.5rc1-3              13    10205  12.so.0.1.2.5rc1-3
- *    1.0.15                  10    10015  10.so.0.1.0.15
- *    1.2.5                   13    10205  12.so.0.1.2.5
- *    1.2.6beta1-4            13    10206  12.so.0.1.2.6beta1-4
- *    1.0.16                  10    10016  10.so.0.1.0.16
- *    1.2.6                   13    10206  12.so.0.1.2.6
- *    1.2.7beta1-2            13    10207  12.so.0.1.2.7beta1-2
- *    1.0.17rc1               10    10017  12.so.0.1.0.17rc1
- *    1.2.7rc1                13    10207  12.so.0.1.2.7rc1
- *    1.0.17                  10    10017  12.so.0.1.0.17
- *    1.2.7                   13    10207  12.so.0.1.2.7
- *    1.2.8beta1-5            13    10208  12.so.0.1.2.8beta1-5
- *    1.0.18rc1-5             10    10018  12.so.0.1.0.18rc1-5
- *    1.2.8rc1-5              13    10208  12.so.0.1.2.8rc1-5
- *    1.0.18                  10    10018  12.so.0.1.0.18
- *    1.2.8                   13    10208  12.so.0.1.2.8
- *    1.2.9beta1-3            13    10209  12.so.0.1.2.9beta1-3
- *    1.2.9beta4-11           13    10209  12.so.0.9[.0]
- *    1.2.9rc1                13    10209  12.so.0.9[.0]
- *    1.2.9                   13    10209  12.so.0.9[.0]
- *    1.2.10beta1-7           13    10210  12.so.0.10[.0]
- *    1.2.10rc1-2             13    10210  12.so.0.10[.0]
- *    1.2.10                  13    10210  12.so.0.10[.0]
- *    1.4.0beta1-5            14    10400  14.so.0.0[.0]
- *    1.2.11beta1-4           13    10211  12.so.0.11[.0]
- *    1.4.0beta7-8            14    10400  14.so.0.0[.0]
- *    1.2.11                  13    10211  12.so.0.11[.0]
- *    1.2.12                  13    10212  12.so.0.12[.0]
- *    1.4.0beta9-14           14    10400  14.so.0.0[.0]
- *    1.2.13                  13    10213  12.so.0.13[.0]
- *    1.4.0beta15-36          14    10400  14.so.0.0[.0]
- *    1.4.0beta37-87          14    10400  14.so.14.0[.0]
- *    1.4.0rc01               14    10400  14.so.14.0[.0]
- *    1.4.0beta88-109         14    10400  14.so.14.0[.0]
- *    1.4.0rc02-08            14    10400  14.so.14.0[.0]
- *    1.4.0                   14    10400  14.so.14.0[.0]
- *    1.4.1beta01-03          14    10401  14.so.14.1[.0]
- *    1.4.1rc01               14    10401  14.so.14.1[.0]
- *    1.4.1beta04-12          14    10401  14.so.14.1[.0]
- *    1.4.1                   14    10401  14.so.14.1[.0]
- *    1.4.2                   14    10402  14.so.14.2[.0]
- *    1.4.3                   14    10403  14.so.14.3[.0]
- *    1.4.4                   14    10404  14.so.14.4[.0]
- *    1.5.0beta01-58          15    10500  15.so.15.0[.0]
- *    1.5.0rc01-07            15    10500  15.so.15.0[.0]
- *    1.5.0                   15    10500  15.so.15.0[.0]
- *    1.5.1beta01-11          15    10501  15.so.15.1[.0]
- *    1.5.1rc01-02            15    10501  15.so.15.1[.0]
- *    1.5.1                   15    10501  15.so.15.1[.0]
- *    1.5.2beta01-03          15    10502  15.so.15.2[.0]
- *    1.5.2rc01-03            15    10502  15.so.15.2[.0]
- *    1.5.2                   15    10502  15.so.15.2[.0]
- *    1.5.3beta01-10          15    10503  15.so.15.3[.0]
- *    1.5.3rc01-02            15    10503  15.so.15.3[.0]
- *    1.5.3beta11             15    10503  15.so.15.3[.0]
- *    1.5.3 [omitted]
- *    1.5.4beta01-08          15    10504  15.so.15.4[.0]
- *    1.5.4rc01               15    10504  15.so.15.4[.0]
- *    1.5.4                   15    10504  15.so.15.4[.0]
- *    1.5.5beta01-08          15    10505  15.so.15.5[.0]
- *    1.5.5rc01               15    10505  15.so.15.5[.0]
- *    1.5.5                   15    10505  15.so.15.5[.0]
- *    1.5.6beta01-07          15    10506  15.so.15.6[.0]
- *    1.5.6rc01-03            15    10506  15.so.15.6[.0]
- *    1.5.6                   15    10506  15.so.15.6[.0]
- *    1.5.7beta01-05          15    10507  15.so.15.7[.0]
- *    1.5.7rc01-03            15    10507  15.so.15.7[.0]
- *    1.5.7                   15    10507  15.so.15.7[.0]
- *    1.6.0beta01-40          16    10600  16.so.16.0[.0]
- *    1.6.0rc01-08            16    10600  16.so.16.0[.0]
- *    1.6.0                   16    10600  16.so.16.0[.0]
- *    1.6.1beta01-09          16    10601  16.so.16.1[.0]
- *    1.6.1rc01               16    10601  16.so.16.1[.0]
- *    1.6.1                   16    10601  16.so.16.1[.0]
- *    1.6.2beta01             16    10602  16.so.16.2[.0]
- *    1.6.2rc01-06            16    10602  16.so.16.2[.0]
- *    1.6.2                   16    10602  16.so.16.2[.0]
- *    1.6.3beta01-11          16    10603  16.so.16.3[.0]
- *    1.6.3rc01               16    10603  16.so.16.3[.0]
- *    1.6.3                   16    10603  16.so.16.3[.0]
- *    1.6.4beta01-02          16    10604  16.so.16.4[.0]
- *    1.6.4rc01               16    10604  16.so.16.4[.0]
- *    1.6.4                   16    10604  16.so.16.4[.0]
- *    1.6.5                   16    10605  16.so.16.5[.0]
- *    1.6.6                   16    10606  16.so.16.6[.0]
- *    1.6.7beta01-04          16    10607  16.so.16.7[.0]
- *    1.6.7rc01-03            16    10607  16.so.16.7[.0]
- *    1.6.7                   16    10607  16.so.16.7[.0]
- *    1.6.8beta01-02          16    10608  16.so.16.8[.0]
- *    1.6.8rc01-02            16    10608  16.so.16.8[.0]
- *    1.6.8                   16    10608  16.so.16.8[.0]
- *    1.6.9beta01-04          16    10609  16.so.16.9[.0]
- *    1.6.9rc01-02            16    10609  16.so.16.9[.0]
- *    1.6.9                   16    10609  16.so.16.9[.0]
- *    1.6.10beta01-03         16    10610  16.so.16.10[.0]
- *    1.6.10rc01-03           16    10610  16.so.16.10[.0]
- *    1.6.10                  16    10610  16.so.16.10[.0]
- *    1.6.11beta01-06         16    10611  16.so.16.11[.0]
- *    1.6.11rc01-02           16    10611  16.so.16.11[.0]
- *    1.6.11                  16    10611  16.so.16.11[.0]
- *    1.6.12rc01-03           16    10612  16.so.16.12[.0]
- *    1.6.12                  16    10612  16.so.16.12[.0]
- *    1.6.13beta01-04         16    10613  16.so.16.13[.0]
- *    1.6.13rc01-02           16    10613  16.so.16.13[.0]
- *    1.6.13                  16    10613  16.so.16.13[.0]
- *    1.6.14beta01-07         16    10614  16.so.16.14[.0]
- *    1.6.14rc01-02           16    10614  16.so.16.14[.0]
- *    1.6.14                  16    10614  16.so.16.14[.0]
- *    1.6.15beta01-08         16    10615  16.so.16.15[.0]
- *    1.6.15rc01-03           16    10615  16.so.16.15[.0]
- *    1.6.15                  16    10615  16.so.16.15[.0]
- *    1.6.16beta01-03         16    10616  16.so.16.16[.0]
- *    1.6.16rc01-02           16    10616  16.so.16.16[.0]
- *    1.6.16                  16    10616  16.so.16.16[.0]
- *    1.6.17beta01-06         16    10617  16.so.16.17[.0]
- *    1.6.17rc01-06           16    10617  16.so.16.17[.0]
- *    1.6.17                  16    10617  16.so.16.17[.0]
- *    1.6.18beta01-09         16    10618  16.so.16.18[.0]
- *    1.6.18rc01-03           16    10618  16.so.16.18[.0]
- *    1.6.18                  16    10618  16.so.16.18[.0]
- *
- *   Henceforth the source version will match the shared-library major
- *   and minor numbers; the shared-library major version number will be
- *   used for changes in backward compatibility, as it is intended.  The
- *   PNG_LIBPNG_VER macro, which is not used within libpng but is available
- *   for applications, is an unsigned integer of the form xyyzz corresponding
- *   to the source version x.y.z (leading zeros in y and z).  Beta versions
- *   were given the previous public release number plus a letter, until
- *   version 1.0.6j; from then on they were given the upcoming public
- *   release number plus "betaNN" or "rcNN".
- *
- *   Binary incompatibility exists only when applications make direct access
- *   to the info_ptr or png_ptr members through png.h, and the compiled
- *   application is loaded with a different version of the library.
- *
- *   DLLNUM will change each time there are forward or backward changes
- *   in binary compatibility (e.g., when a new feature is added).
- *
- * See libpng-manual.txt or libpng.3 for more information.  The PNG
- * specification is available as a W3C Recommendation and as an ISO
- * Specification, <http://www.w3.org/TR/2003/REC-PNG-20031110/
  */
 
 /*
@@ -250,12 +24,14 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.0.7, July 1, 2000, through 1.6.18, July 23, 2015, are
- * Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, and are
- * distributed according to the same disclaimer and license as libpng-1.0.6
- * with the following individuals added to the list of Contributing Authors:
+ * libpng versions 1.0.7, July 1, 2000, through 1.6.19, November 12, 2015, are
+ * Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+ * derived from libpng-1.0.6, and are distributed according to the same
+ * disclaimer and license as libpng-1.0.6 with the following individuals
+ * added to the list of Contributing Authors:
  *
  *    Simon-Pierre Cadieux
+ *    Eric S. Raymond
  *    Mans Rullgard
  *    Cosmin Truta
  *    Gilles Vollant
@@ -271,19 +47,20 @@
  *    the user.
  *
  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
- * Copyright (c) 1998-2000 Glenn Randers-Pehrson, and are distributed according
- * to the same disclaimer and license as libpng-0.96, with the following
- * individuals added to the list of Contributing Authors:
+ * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+ * libpng-0.96, and are distributed according to the same disclaimer and
+ * license as libpng-0.96, with the following individuals added to the list
+ * of Contributing Authors:
  *
  *    Tom Lane
  *    Glenn Randers-Pehrson
- *    Eric S. Raymond
  *    Willem van Schaik
  *
  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
- * Copyright (c) 1996-1997 Andreas Dilger, and are
- * distributed according to the same disclaimer and license as libpng-0.88,
- * with the following individuals added to the list of Contributing Authors:
+ * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+ * and are distributed according to the same disclaimer and license as
+ * libpng-0.88, with the following individuals added to the list of
+ * Contributing Authors:
  *
  *    John Bowler
  *    Kevin Bracey
@@ -329,6 +106,8 @@
  * supporting the PNG file format in commercial products.  If you use this
  * source code in a product, acknowledgment is not required but would be
  * appreciated.
+ *
+ * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
  */
 
 /*
@@ -355,17 +134,92 @@
  * Thanks to Frank J. T. Wojcik for helping with the documentation.
  */
 
+/* Note about libpng version numbers:
+ *
+ *    Due to various miscommunications, unforeseen code incompatibilities
+ *    and occasional factors outside the authors' control, version numbering
+ *    on the library has not always been consistent and straightforward.
+ *    The following table summarizes matters since version 0.89c, which was
+ *    the first widely used release:
+ *
+ *    source                 png.h  png.h  shared-lib
+ *    version                string   int  version
+ *    -------                ------ -----  ----------
+ *    0.89c "1.0 beta 3"     0.89      89  1.0.89
+ *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
+ *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
+ *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
+ *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
+ *    0.97c                  0.97      97  2.0.97
+ *    0.98                   0.98      98  2.0.98
+ *    0.99                   0.99      98  2.0.99
+ *    0.99a-m                0.99      99  2.0.99
+ *    1.00                   1.00     100  2.1.0 [100 should be 10000]
+ *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
+ *    1.0.1       png.h string is   10001  2.1.0
+ *    1.0.1a-e    identical to the  10002  from here on, the shared library
+ *    1.0.2       source version)   10002  is 2.V where V is the source code
+ *    1.0.2a-b                      10003  version, except as noted.
+ *    1.0.3                         10003
+ *    1.0.3a-d                      10004
+ *    1.0.4                         10004
+ *    1.0.4a-f                      10005
+ *    1.0.5 (+ 2 patches)           10005
+ *    1.0.5a-d                      10006
+ *    1.0.5e-r                      10100 (not source compatible)
+ *    1.0.5s-v                      10006 (not binary compatible)
+ *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
+ *    1.0.6d-f                      10007 (still binary incompatible)
+ *    1.0.6g                        10007
+ *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
+ *    1.0.6i                        10007  10.6i
+ *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
+ *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
+ *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
+ *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
+ *    1.0.7                    1    10007  (still compatible)
+ *    ...
+ *    1.0.19                  10    10019  10.so.0.19[.0]
+ *    ...
+ *    1.2.53                  13    10253  12.so.0.53[.0]
+ *    ...
+ *    1.5.23                  15    10523  15.so.15.23[.0]
+ *    ...
+ *    1.6.19                  16    10619  16.so.16.19[.0]
+ *
+ *    Henceforth the source version will match the shared-library major
+ *    and minor numbers; the shared-library major version number will be
+ *    used for changes in backward compatibility, as it is intended.  The
+ *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
+ *    for applications, is an unsigned integer of the form xyyzz corresponding
+ *    to the source version x.y.z (leading zeros in y and z).  Beta versions
+ *    were given the previous public release number plus a letter, until
+ *    version 1.0.6j; from then on they were given the upcoming public
+ *    release number plus "betaNN" or "rcNN".
+ *
+ *    Binary incompatibility exists only when applications make direct access
+ *    to the info_ptr or png_ptr members through png.h, and the compiled
+ *    application is loaded with a different version of the library.
+ *
+ *    DLLNUM will change each time there are forward or backward changes
+ *    in binary compatibility (e.g., when a new feature is added).
+ *
+ * See libpng.txt or libpng.3 for more information.  The PNG specification
+ * is available as a W3C Recommendation and as an ISO Specification,
+ * <http://www.w3.org/TR/2003/REC-PNG-20031110/
+ */
+
 /*
  * Y2K compliance in libpng:
  * =========================
  *
- *    July 23, 2015
+ *    November 12, 2015
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.6.18 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.19 are Y2K compliant.  It is my belief that
  *    earlier versions were also Y2K compliant.
  *
  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -427,9 +281,9 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.18"
+#define PNG_LIBPNG_VER_STRING "1.6.19"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.18 - July 23, 2015\n"
+     " libpng version 1.6.19 - November 12, 2015\n"
 
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -437,7 +291,7 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   6
-#define PNG_LIBPNG_VER_RELEASE 18
+#define PNG_LIBPNG_VER_RELEASE 19
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -468,7 +322,7 @@
  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  */
-#define PNG_LIBPNG_VER 10618 /* 1.6.18 */
+#define PNG_LIBPNG_VER 10619 /* 1.6.19 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -525,17 +379,22 @@ extern "C" {
 
 /* This file is arranged in several sections:
  *
- * 1. Any configuration options that can be specified by for the application
+ * 1. [omitted]
+ * 2. Any configuration options that can be specified by for the application
  *    code when it is built.  (Build time configuration is in pnglibconf.h)
- * 2. Type definitions (base types are defined in pngconf.h), structure
+ * 3. Type definitions (base types are defined in pngconf.h), structure
  *    definitions.
- * 3. Exported library functions.
- * 4. Simplified API.
+ * 4. Exported library functions.
+ * 5. Simplified API.
+ * 6. Implementation options.
  *
  * The library source code has additional files (principally pngpriv.h) that
  * allow configuration of the library.
  */
-/* Section 1: run time configuration
+
+/* Section 1: [omitted] */
+
+/* Section 2: run time configuration
  * See pnglibconf.h for build time configuration
  *
  * Run time configuration allows the application to choose between
@@ -565,7 +424,7 @@ extern "C" {
  * Otherwise the calls are mapped to png_error.
  */
 
-/* Section 2: type definitions, including structures and compile time
+/* Section 3: type definitions, including structures and compile time
  * constants.
  * See pngconf.h for base types that vary by machine/system
  */
@@ -573,7 +432,7 @@ extern "C" {
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
-typedef char* png_libpng_version_1_6_18;
+typedef char* png_libpng_version_1_6_19;
 
 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
  *
@@ -889,7 +748,9 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
 #define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */
 #define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */
 #define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
+#if INT_MAX >= 0x8000 /* else this might break */
 #define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */
+#endif
 
 /* This is used for the transformation routines, as some of them
  * change these values for the row.  It also should enable using
@@ -993,7 +854,9 @@ PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
 #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */
 /* Added to libpng-1.5.4 */
 #define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */
+#if INT_MAX >= 0x8000 /* else this might break */
 #define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */
+#endif
 
 /* Flags for MNG supported features */
 #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
@@ -1010,7 +873,7 @@ typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
     png_alloc_size_t));
 typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
 
-/* Section 3: exported functions
+/* Section 4: exported functions
  * Here are the function definitions most commonly used.  This is not
  * the place to find out how to use libpng.  See libpng-manual.txt for the
  * full explanation, see example.c for the summary.  This just provides
@@ -1383,13 +1246,13 @@ PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
 #endif
 
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
-/* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
+/* Add a filler byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
 PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
     int flags));
 /* The values of the PNG_FILLER_ defines should NOT be changed */
 #  define PNG_FILLER_BEFORE 0
 #  define PNG_FILLER_AFTER 1
-/* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
+/* Add an alpha byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
 PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
     png_uint_32 filler, int flags));
 #endif /* READ_FILLER || WRITE_FILLER */
@@ -2714,7 +2577,7 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
 
 #  define PNG_get_int_32(buf) \
      ((png_int_32)((*(buf) & 0x80) \
-      ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
+      ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
       : (png_int_32)png_get_uint_32(buf)))
 
    /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
@@ -2734,10 +2597,17 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
 #  endif
 #endif
 
-#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
-    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+PNG_EXPORT(242, void, png_set_check_for_invalid_index,
+    (png_structrp png_ptr, int allowed));
+#  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
+PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
+    png_const_infop info_ptr));
+#  endif
+#endif /* CHECK_FOR_INVALID_INDEX */
+
 /*******************************************************************************
- *  SIMPLIFIED API
+ * Section 5: SIMPLIFIED API
  *******************************************************************************
  *
  * Please read the documentation in libpng-manual.txt (TODO: write said
@@ -2782,6 +2652,9 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
  * when it is being read or defines the in-memory format of an image that you
  * need to write:
  */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
+    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+
 #define PNG_IMAGE_VERSION 1
 
 typedef struct png_control *png_controlp;
@@ -2881,7 +2754,7 @@ typedef struct
  * called to read or write the color-map and set the format correctly for the
  * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
  *
- * NOTE: libpng can be built with particular features disabled, if you see
+ * NOTE: libpng can be built with particular features disabled. If you see
  * compiler errors because the definition of one of the following flags has been
  * compiled out it is because libpng does not have the required support.  It is
  * possible, however, for the libpng configuration to enable the format on just
@@ -2893,7 +2766,7 @@ typedef struct
  */
 #define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */
 #define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */
-#define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2 byte channels else 1 byte */
+#define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2-byte channels else 1-byte */
 #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
 
 #ifdef PNG_FORMAT_BGR_SUPPORTED
@@ -3193,17 +3066,8 @@ PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
  ******************************************************************************/
 #endif /* SIMPLIFIED_{READ|WRITE} */
 
-#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
-PNG_EXPORT(242, void, png_set_check_for_invalid_index,
-    (png_structrp png_ptr, int allowed));
-#  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
-PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
-    png_const_infop info_ptr));
-#  endif
-#endif /* CHECK_FOR_INVALID_INDEX */
-
 /*******************************************************************************
- *  IMPLEMENTATION OPTIONS
+ * Section 6: IMPLEMENTATION OPTIONS
  *******************************************************************************
  *
  * Support for arbitrary implementation-specific optimizations.  The API allows
diff --git a/pngconf.h b/pngconf.h
index 62e37cf2b..f1b795b47 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.6.18, July 23, 2015
+ * libpng version 1.6.19, July 23, 2015
  *
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -63,7 +63,7 @@
  */
 #define PNG_CONST const /* backward compatibility only */
 
-/* This controls optimization of the reading of 16 and 32 bit values
+/* This controls optimization of the reading of 16-bit and 32-bit values
  * from PNG files.  It can be set on a per-app-file basis - it
  * just changes whether a macro is used when the function is called.
  * The library builder sets the default; if read functions are not
@@ -480,7 +480,7 @@
 #if CHAR_BIT == 8 && UCHAR_MAX == 255
    typedef unsigned char png_byte;
 #else
-#  error "libpng requires 8 bit bytes"
+#  error "libpng requires 8-bit bytes"
 #endif
 
 #if INT_MIN == -32768 && INT_MAX == 32767
@@ -488,7 +488,7 @@
 #elif SHRT_MIN == -32768 && SHRT_MAX == 32767
    typedef short png_int_16;
 #else
-#  error "libpng requires a signed 16 bit type"
+#  error "libpng requires a signed 16-bit type"
 #endif
 
 #if UINT_MAX == 65535
@@ -496,7 +496,7 @@
 #elif USHRT_MAX == 65535
    typedef unsigned short png_uint_16;
 #else
-#  error "libpng requires an unsigned 16 bit type"
+#  error "libpng requires an unsigned 16-bit type"
 #endif
 
 #if INT_MIN < -2147483646 && INT_MAX > 2147483646
@@ -504,7 +504,7 @@
 #elif LONG_MIN < -2147483646 && LONG_MAX > 2147483646
    typedef long int png_int_32;
 #else
-#  error "libpng requires a signed 32 bit (or more) type"
+#  error "libpng requires a signed 32-bit (or more) type"
 #endif
 
 #if UINT_MAX > 4294967294
@@ -512,7 +512,7 @@
 #elif ULONG_MAX > 4294967294
    typedef unsigned long int png_uint_32;
 #else
-#  error "libpng requires an unsigned 32 bit (or more) type"
+#  error "libpng requires an unsigned 32-bit (or more) type"
 #endif
 
 /* Prior to 1.6.0 it was possible to disable the use of size_t, 1.6.0, however,
diff --git a/pngpread.c b/pngpread.c
index 2d4a86269..9f68f9902 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -563,7 +563,7 @@ png_push_read_IDAT(png_structrp png_ptr)
        * are of different types and we don't know which variable has the fewest
        * bits.  Carefully select the smaller and cast it to the type of the
        * larger - this cannot overflow.  Do not cast in the following test - it
-       * will break on either 16 or 64 bit platforms.
+       * will break on either 16-bit or 64-bit platforms.
        */
       if (idat_size < save_size)
          save_size = (png_size_t)idat_size;
diff --git a/pngpriv.h b/pngpriv.h
index 199750328..c466d4bfe 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -575,10 +575,6 @@
 #define PNG_STRUCT_PNG   0x0001
 #define PNG_STRUCT_INFO  0x0002
 
-/* Scaling factor for filter heuristic weighting calculations */
-#define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
-#define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))
-
 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
 #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
 #define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
@@ -669,7 +665,7 @@
 /* The fixed point conversion performs range checking and evaluates
  * its argument multiple times, so must be used with care.  The
  * range checking uses the PNG specification values for a signed
- * 32 bit fixed point value except that the values are deliberately
+ * 32-bit fixed point value except that the values are deliberately
  * rounded-to-zero to an integral value - 21474 (21474.83 is roughly
  * (2^31-1) * 100000). 's' is a string that describes the value being
  * converted.
@@ -816,7 +812,7 @@
     */
 #endif
 
-/* This is used for 16 bit gamma tables -- only the top level pointers are
+/* This is used for 16-bit gamma tables -- only the top level pointers are
  * const; this could be changed:
  */
 typedef const png_uint_16p * png_const_uint_16pp;
diff --git a/pngread.c b/pngread.c
index e88151c20..48aae8488 100644
--- a/pngread.c
+++ b/pngread.c
@@ -1683,10 +1683,11 @@ decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
          value *= 257;
          break;
 
+#ifdef __GNUC__
       default:
          png_error(display->image->opaque->png_ptr,
             "unexpected encoding (internal error)");
-         break;
+#endif
    }
 
    return value;
@@ -2847,10 +2848,6 @@ png_image_read_colormap(png_voidp argument)
 
    switch (data_encoding)
    {
-      default:
-         png_error(png_ptr, "bad data option (internal error)");
-         break;
-
       case P_sRGB:
          /* Change to 8-bit sRGB */
          png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
@@ -2860,6 +2857,11 @@ png_image_read_colormap(png_voidp argument)
          if (png_ptr->bit_depth > 8)
             png_set_scale_16(png_ptr);
          break;
+
+#ifdef __GNUC__
+      default:
+         png_error(png_ptr, "bad data option (internal error)");
+#endif
    }
 
    if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
@@ -3410,10 +3412,6 @@ png_image_read_background(png_voidp argument)
     */
    switch (info_ptr->bit_depth)
    {
-      default:
-         png_error(png_ptr, "unexpected bit depth");
-         break;
-
       case 8:
          /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
           * to be removed by composing on a background: either the row if
@@ -3631,6 +3629,11 @@ png_image_read_background(png_voidp argument)
             }
          }
          break;
+
+#ifdef __GNUC__
+      default:
+         png_error(png_ptr, "unexpected bit depth");
+#endif
    }
 
    return 1;
diff --git a/pngrio.c b/pngrio.c
index bb5c82510..38f7fd49d 100644
--- a/pngrio.c
+++ b/pngrio.c
@@ -26,7 +26,7 @@
  * reads from a file pointer.  Note that this routine sometimes gets called
  * with very small lengths, so you should implement some kind of simple
  * buffering if you are using unbuffered reads.  This should never be asked
- * to read more than 64K on a 16 bit machine.
+ * to read more than 64K on a 16-bit machine.
  */
 void /* PRIVATE */
 png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length)
diff --git a/pngrtran.c b/pngrtran.c
index 4c84d30f2..f129ef129 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1,7 +1,7 @@
 
 /* pngrtran.c - transforms the data in a row for PNG readers
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -976,7 +976,6 @@ png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,
 
       default:
          png_error(png_ptr, "invalid error action to rgb_to_gray");
-         break;
    }
 
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
@@ -1997,7 +1996,7 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
 #     endif
 
 #  else
-      /* No 16 bit support: force chopping 16-bit input down to 8, in this case
+      /* No 16-bit support: force chopping 16-bit input down to 8, in this case
        * the app program can chose if both APIs are available by setting the
        * correct scaling to use.
        */
@@ -2098,10 +2097,10 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
    if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
    {
-      if (info_ptr->bit_depth < png_ptr->user_transform_depth)
+      if (png_ptr->user_transform_depth != 0)
          info_ptr->bit_depth = png_ptr->user_transform_depth;
 
-      if (info_ptr->channels < png_ptr->user_transform_channels)
+      if (png_ptr->user_transform_channels != 0)
          info_ptr->channels = png_ptr->user_transform_channels;
    }
 #endif
@@ -2382,8 +2381,8 @@ png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
 
       while (sp < ep)
       {
-         /* The input is an array of 16 bit components, these must be scaled to
-          * 8 bits each.  For a 16 bit value V the required value (from the PNG
+         /* The input is an array of 16-bit components, these must be scaled to
+          * 8 bits each.  For a 16-bit value V the required value (from the PNG
           * specification) is:
           *
           *    (V * 255) / 65535
@@ -2404,7 +2403,7 @@ png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
           *
           * The approximate differs from the exact answer only when (vlo-vhi) is
           * 128; it then gives a correction of +1 when the exact correction is
-          * 0.  This gives 128 errors.  The exact answer (correct for all 16 bit
+          * 0.  This gives 128 errors.  The exact answer (correct for all 16-bit
           * input values) is:
           *
           *    error = (vlo-vhi+128)*65535 >> 24;
@@ -3148,9 +3147,9 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
                if (red != green || red != blue)
                   rgb_error |= 1;
 
-               /* From 1.5.5 in the 16 bit case do the accurate conversion even
+               /* From 1.5.5 in the 16-bit case do the accurate conversion even
                 * in the 'fast' case - this is because this is where the code
-                * ends up when handling linear 16 bit data.
+                * ends up when handling linear 16-bit data.
                 */
                gray16  = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
                   15);
@@ -3315,7 +3314,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         if ((png_uint_16)((*sp >> shift) & 0x0f)
                             == png_ptr->trans_color.gray)
                         {
-                           unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+                           unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
                            tmp |= png_ptr->background.gray << shift;
                            *sp = (png_byte)(tmp & 0xff);
                         }
@@ -3325,7 +3324,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                            unsigned int p = (*sp >> shift) & 0x0f;
                            unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
                               0x0f;
-                           unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+                           unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
                            tmp |= g << shift;
                            *sp = (png_byte)(tmp & 0xff);
                         }
@@ -3351,7 +3350,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         if ((png_uint_16)((*sp >> shift) & 0x0f)
                             == png_ptr->trans_color.gray)
                         {
-                           unsigned int tmp = *sp & (0xf0f >> (4 - shift));
+                           unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
                            tmp |= png_ptr->background.gray << shift;
                            *sp = (png_byte)(tmp & 0xff);
                         }
diff --git a/pngrutil.c b/pngrutil.c
index 8f8edbc58..ee584a8c4 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -89,7 +89,13 @@ png_get_int_32)(png_const_bytep buf)
       return uval;
 
    uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
-   return -(png_int_32)uval;
+   if ((uval & 0x80000000) == 0) /* no overflow */
+       return -(png_int_32)uval;
+   /* The following has to be safe; this function only gets called on PNG data
+    * and if we get here that data is invalid.  0 is the most safe value and
+    * if not then an attacker would surely just generate a PNG with 0 instead.
+    */
+   return 0;
 }
 
 /* Grab an unsigned 16-bit integer from a buffer in big-endian format. */
@@ -98,7 +104,7 @@ png_get_uint_16)(png_const_bytep buf)
 {
    /* ANSI-C requires an int value to accomodate at least 16 bits so this
     * works and allows the compiler not to worry about possible narrowing
-    * on 32 bit systems.  (Pre-ANSI systems did not make integers smaller
+    * on 32-bit systems.  (Pre-ANSI systems did not make integers smaller
     * than 16 bits either.)
     */
    unsigned int val =
@@ -866,7 +872,7 @@ void /* PRIVATE */
 png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
    png_color palette[PNG_MAX_PALETTE_LENGTH];
-   int num, i;
+   int max_palette_length, num, i;
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    png_colorp pal_ptr;
 #endif
@@ -927,6 +933,19 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    /* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
    num = (int)length / 3;
 
+   /* If the palette has 256 or fewer entries but is too large for the bit
+    * depth, we don't issue an error, to preserve the behavior of previous
+    * libpng versions. We silently truncate the unused extra palette entries
+    * here.
+    */
+   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+      max_palette_length = (1 << png_ptr->bit_depth);
+   else
+      max_palette_length = PNG_MAX_PALETTE_LENGTH;
+
+   if (num > max_palette_length)
+      num = max_palette_length;
+
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
    {
@@ -959,7 +978,7 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
    {
-      png_crc_finish(png_ptr, 0);
+      png_crc_finish(png_ptr, (int) length - num * 3);
    }
 
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
@@ -1818,7 +1837,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
          return;
       }
 
-      if (length > png_ptr->num_palette ||
+      if (length > (unsigned int) png_ptr->num_palette ||
          length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
          length == 0)
       {
@@ -1982,7 +2001,8 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 
    num = length / 2 ;
 
-   if (num != png_ptr->num_palette || num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
+   if (num != (unsigned int) png_ptr->num_palette ||
+       num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
    {
       png_crc_finish(png_ptr, length);
       png_chunk_benign_error(png_ptr, "invalid");
diff --git a/pngset.c b/pngset.c
index 5f62af168..05a2134db 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -123,12 +123,12 @@ png_set_cHRM_XYZ(png_const_structrp png_ptr, png_inforp info_ptr, double red_X,
       png_fixed(png_ptr, red_X, "cHRM Red X"),
       png_fixed(png_ptr, red_Y, "cHRM Red Y"),
       png_fixed(png_ptr, red_Z, "cHRM Red Z"),
-      png_fixed(png_ptr, green_X, "cHRM Red X"),
-      png_fixed(png_ptr, green_Y, "cHRM Red Y"),
-      png_fixed(png_ptr, green_Z, "cHRM Red Z"),
-      png_fixed(png_ptr, blue_X, "cHRM Red X"),
-      png_fixed(png_ptr, blue_Y, "cHRM Red Y"),
-      png_fixed(png_ptr, blue_Z, "cHRM Red Z"));
+      png_fixed(png_ptr, green_X, "cHRM Green X"),
+      png_fixed(png_ptr, green_Y, "cHRM Green Y"),
+      png_fixed(png_ptr, green_Z, "cHRM Green Z"),
+      png_fixed(png_ptr, blue_X, "cHRM Blue X"),
+      png_fixed(png_ptr, blue_Y, "cHRM Blue Y"),
+      png_fixed(png_ptr, blue_Z, "cHRM Blue Z"));
 }
 #  endif /* FLOATING_POINT */
 
@@ -513,12 +513,17 @@ png_set_PLTE(png_structrp png_ptr, png_inforp info_ptr,
     png_const_colorp palette, int num_palette)
 {
 
+   png_uint_32 max_palette_length;
+
    png_debug1(1, "in %s storage function", "PLTE");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   if (num_palette < 0 || num_palette > PNG_MAX_PALETTE_LENGTH)
+   max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
+      (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
+
+   if (num_palette < 0 || num_palette > (int) max_palette_length)
    {
       if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
          png_error(png_ptr, "Invalid palette length");
@@ -551,8 +556,8 @@ png_set_PLTE(png_structrp png_ptr, png_inforp info_ptr,
    png_free_data(png_ptr, info_ptr, PNG_FREE_PLTE, 0);
 
    /* Changed in libpng-1.2.1 to allocate PNG_MAX_PALETTE_LENGTH instead
-    * of num_palette entries, in case of an invalid PNG file that has
-    * too-large sample values.
+    * of num_palette entries, in case of an invalid PNG file or incorrect
+    * call to png_set_PLTE() with too-large sample values.
     */
    png_ptr->palette = png_voidcast(png_colorp, png_calloc(png_ptr,
        PNG_MAX_PALETTE_LENGTH * (sizeof (png_color))));
@@ -709,7 +714,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
 {
    int i;
 
-   png_debug1(1, "in %lx storage function", png_ptr == NULL ? 0xabadca11 :
+   png_debug1(1, "in %lx storage function", png_ptr == NULL ? 0xabadca11U :
       (unsigned long)png_ptr->chunk_name);
 
    if (png_ptr == NULL || info_ptr == NULL || num_text <= 0 || text_ptr == NULL)
@@ -1568,7 +1573,7 @@ png_set_user_limits (png_structrp png_ptr, png_uint_32 user_width_max,
 {
    /* Images with dimensions larger than these limits will be
     * rejected by png_set_IHDR().  To accept any PNG datastream
-    * regardless of dimensions, set both limits to 0x7ffffffL.
+    * regardless of dimensions, set both limits to 0x7ffffff.
     */
    if (png_ptr == NULL)
       return;
diff --git a/pngtest.c b/pngtest.c
index 84745b6d4..bb0a0b534 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -1,7 +1,7 @@
 
 /* pngtest.c - a simple test program to test libpng
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -60,6 +60,7 @@
    defined PNG_READ_pHYs_SUPPORTED &&\
    defined PNG_READ_sBIT_SUPPORTED &&\
    defined PNG_READ_sCAL_SUPPORTED &&\
+   defined PNG_READ_sPLT_SUPPORTED &&\
    defined PNG_READ_sRGB_SUPPORTED &&\
    defined PNG_READ_tEXt_SUPPORTED &&\
    defined PNG_READ_tIME_SUPPORTED &&\
@@ -1057,7 +1058,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #ifndef PNG_READ_INTERLACING_SUPPORTED
          /* num_pass will not be set below, set it here if the image is
           * interlaced: what happens is that write interlacing is *not* turned
-          * on an the partial interlaced rows are written directly.
+          * on and the partial interlaced rows are written directly.
           */
          switch (interlace_type)
          {
@@ -1076,6 +1077,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #endif
       }
    }
+
 #ifdef PNG_FIXED_POINT_SUPPORTED
 #ifdef PNG_cHRM_SUPPORTED
    {
@@ -1090,6 +1092,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
+
 #ifdef PNG_gAMA_SUPPORTED
    {
       png_fixed_point gamma;
@@ -1123,6 +1126,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #endif
 #endif /* Floating point */
 #endif /* Fixed point */
+
 #ifdef PNG_iCCP_SUPPORTED
    {
       png_charp name;
@@ -1138,6 +1142,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
+
 #ifdef PNG_sRGB_SUPPORTED
    {
       int intent;
@@ -1146,6 +1151,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_set_sRGB(write_ptr, write_info_ptr, intent);
    }
 #endif
+
    {
       png_colorp palette;
       int num_palette;
@@ -1153,6 +1159,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       if (png_get_PLTE(read_ptr, read_info_ptr, &palette, &num_palette) != 0)
          png_set_PLTE(write_ptr, write_info_ptr, palette, num_palette);
    }
+
 #ifdef PNG_bKGD_SUPPORTED
    {
       png_color_16p background;
@@ -1163,6 +1170,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
+
 #ifdef PNG_hIST_SUPPORTED
    {
       png_uint_16p hist;
@@ -1171,6 +1179,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_set_hIST(write_ptr, write_info_ptr, hist);
    }
 #endif
+
 #ifdef PNG_oFFs_SUPPORTED
    {
       png_int_32 offset_x, offset_y;
@@ -1183,6 +1192,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
+
 #ifdef PNG_pCAL_SUPPORTED
    {
       png_charp purpose, units;
@@ -1198,6 +1208,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       }
    }
 #endif
+
 #ifdef PNG_pHYs_SUPPORTED
    {
       png_uint_32 res_x, res_y;
@@ -1208,6 +1219,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_set_pHYs(write_ptr, write_info_ptr, res_x, res_y, unit_type);
    }
 #endif
+
 #ifdef PNG_sBIT_SUPPORTED
    {
       png_color_8p sig_bit;
@@ -1216,6 +1228,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_set_sBIT(write_ptr, write_info_ptr, sig_bit);
    }
 #endif
+
 #ifdef PNG_sCAL_SUPPORTED
 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
    defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
@@ -1242,9 +1255,22 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
              scal_height);
       }
    }
-#endif
-#endif
-#endif
+#endif /* FIXED_POINT */
+#endif /* FLOATING_POINT */
+#endif /* sCAL */
+
+#ifdef PNG_sPLT_SUPPORTED
+   {
+       png_sPLT_tp entries;
+
+       int num_entries = (int) png_get_sPLT(read_ptr, read_info_ptr, &entries);
+       if (num_entries)
+       {
+           png_set_sPLT(write_ptr, write_info_ptr, entries, num_entries);
+       }
+   }
+#endif /* sPLT */
+
 #ifdef PNG_TEXT_SUPPORTED
    {
       png_textp text_ptr;
@@ -1271,7 +1297,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_set_text(write_ptr, write_info_ptr, text_ptr, num_text);
       }
    }
-#endif
+#endif /* TEXT */
+
 #ifdef PNG_tIME_SUPPORTED
    {
       png_timep mod_time;
@@ -1293,7 +1320,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #endif /* TIME_RFC1123 */
       }
    }
-#endif
+#endif /* tIME */
+
 #ifdef PNG_tRNS_SUPPORTED
    {
       png_bytep trans_alpha;
@@ -1315,7 +1343,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
                trans_color);
       }
    }
-#endif
+#endif /* tRNS */
+
 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
    {
       png_unknown_chunkp unknowns;
@@ -2028,4 +2057,4 @@ main(void)
 #endif
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_18 Your_png_h_is_not_version_1_6_18;
+typedef png_libpng_version_1_6_19 Your_png_h_is_not_version_1_6_19;
diff --git a/pngtrans.c b/pngtrans.c
index 439201744..0c0d92d8f 100644
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -30,7 +30,7 @@ png_set_bgr(png_structrp png_ptr)
 #endif
 
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
-/* Turn on 16 bit byte swapping */
+/* Turn on 16-bit byte swapping */
 void PNGAPI
 png_set_swap(png_structrp png_ptr)
 {
@@ -313,7 +313,7 @@ png_do_invert(png_row_infop row_info, png_bytep row)
 
 #ifdef PNG_16BIT_SUPPORTED
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
-/* Swaps byte order on 16 bit depth images */
+/* Swaps byte order on 16-bit depth images */
 void /* PRIVATE */
 png_do_swap(png_row_infop row_info, png_bytep row)
 {
diff --git a/pngwio.c b/pngwio.c
index 0a40948aa..db76e6b8d 100644
--- a/pngwio.c
+++ b/pngwio.c
@@ -26,7 +26,7 @@
  * writes to a file pointer.  Note that this routine sometimes gets called
  * with very small lengths, so you should implement some kind of simple
  * buffering if you are using unbuffered writes.  This should never be asked
- * to write more than 64K on a 16 bit machine.
+ * to write more than 64K on a 16-bit machine.
  */
 
 void /* PRIVATE */
diff --git a/pngwrite.c b/pngwrite.c
index 3c8cbbe5e..0d4ee9f7a 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,7 +1,7 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -206,7 +206,7 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
       png_write_PLTE(png_ptr, info_ptr->palette,
           (png_uint_32)info_ptr->num_palette);
 
-   else if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) !=0)
+   else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       png_error(png_ptr, "Valid palette required for paletted images");
 
 #ifdef PNG_WRITE_tRNS_SUPPORTED
@@ -1422,7 +1422,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
       png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
 #endif
 
-   /* Swap bits of 1, 2, 4 bit packed pixel formats */
+   /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
    if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
       png_set_packswap(png_ptr);
@@ -1998,7 +1998,7 @@ png_image_write_main(png_voidp argument)
    /* Now set up the data transformations (*after* the header is written),
     * remove the handled transformations from the 'format' flags for checking.
     *
-    * First check for a little endian system if writing 16 bit files.
+    * First check for a little endian system if writing 16-bit files.
     */
    if (write_16bit != 0)
    {
diff --git a/pngwutil.c b/pngwutil.c
index 9e6019e55..adc4729c2 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Last changed in libpng 1.6.19 [November 12, 2015]
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -179,7 +179,7 @@ png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
    if (png_ptr == NULL)
       return;
 
-   /* On 64 bit architectures 'length' may not fit in a png_uint_32. */
+   /* On 64-bit architectures 'length' may not fit in a png_uint_32. */
    if (length > PNG_UINT_31_MAX)
       png_error(png_ptr, "length exceeds PNG maximum");
 
@@ -922,17 +922,20 @@ void /* PRIVATE */
 png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
     png_uint_32 num_pal)
 {
-   png_uint_32 i;
+   png_uint_32 max_palette_length, i;
    png_const_colorp pal_ptr;
    png_byte buf[3];
 
    png_debug(1, "in png_write_PLTE");
 
+   max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
+      (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
+
    if ((
 #ifdef PNG_MNG_FEATURES_SUPPORTED
        (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
 #endif
-       num_pal == 0) || num_pal > 256)
+       num_pal == 0) || num_pal > max_palette_length)
    {
       if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
@@ -1444,7 +1447,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
 
    else if (color_type == PNG_COLOR_TYPE_GRAY)
    {
-      /* One 16 bit value */
+      /* One 16-bit value */
       if (tran->gray >= (1 << png_ptr->bit_depth))
       {
          png_app_warning(png_ptr,
@@ -1459,7 +1462,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
 
    else if (color_type == PNG_COLOR_TYPE_RGB)
    {
-      /* Three 16 bit values */
+      /* Three 16-bit values */
       png_save_uint_16(buf, tran->red);
       png_save_uint_16(buf + 2, tran->green);
       png_save_uint_16(buf + 4, tran->blue);
@@ -2651,7 +2654,6 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 
       if (sum < mins)
       {
-         mins = sum;
          best_row = png_ptr->try_row;
          if (png_ptr->tst_row != NULL)
          {
diff --git a/projects/vstudio/readme.txt b/projects/vstudio/readme.txt
index 096e86fb1..089296873 100644
--- a/projects/vstudio/readme.txt
+++ b/projects/vstudio/readme.txt
@@ -1,7 +1,7 @@
 
 VisualStudio instructions
 
-libpng version 1.6.18 - July 23, 2015
+libpng version 1.6.19 - November 12, 2015
 
 Copyright (c) 1998-2010 Glenn Randers-Pehrson
 
diff --git a/projects/vstudio/zlib.props b/projects/vstudio/zlib.props
index 89c38f3e1..f137678fc 100644
--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
  * zlib.props - location of zlib source
  *
- * libpng version 1.6.18 - July 23, 2015
+ * libpng version 1.6.19 - November 12, 2015
  *
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  *
diff --git a/scripts/README.txt b/scripts/README.txt
index 7d98b6629..71841899c 100644
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@
 
-Makefiles for  libpng version 1.6.18 - July 23, 2015
+Makefiles for  libpng version 1.6.19 - November 12, 2015
 
 pnglibconf.h.prebuilt       =>  Stores configuration settings
  makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.18)
+                       (gcc, creates libpng16.so.16.1.6.19)
  makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
  makefile.knr      =>  Archaic UNIX Makefile that converts files with
                        ansi2knr (Requires ansi2knr.c from
@@ -33,12 +33,12 @@ pnglibconf.h.prebuilt       =>  Stores configuration settings
  makefile.os2      =>  OS/2 Makefile (gcc and emx, requires libpng.def)
  makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
  makefile.sggcc    =>  Silicon Graphics (gcc,
-                       creates libpng16.so.16.1.6.18)
+                       creates libpng16.so.16.1.6.19)
  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
  makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.18)
+                       creates libpng16.so.16.1.6.19)
  makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.18)
+                       creates libpng16.so.16.1.6.19)
  makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
  makefile.sunos    =>  Sun makefile
  makefile.32sunu   =>  Sun Ultra 32-bit makefile
diff --git a/scripts/def.c b/scripts/def.c
index ad68d3b0c..38a9a1663 100644
--- a/scripts/def.c
+++ b/scripts/def.c
@@ -21,7 +21,7 @@ PNG_DFN "OS2 DESCRIPTION "PNG image compression library""
 PNG_DFN "OS2 CODE PRELOAD MOVEABLE DISCARDABLE"
 PNG_DFN ""
 PNG_DFN "EXPORTS"
-PNG_DFN ";Version 1.6.18"
+PNG_DFN ";Version 1.6.19"
 
 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
         PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"
diff --git a/scripts/libpng-config-head.in b/scripts/libpng-config-head.in
index 77fab3803..77652c600 100644
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@
 
 # Modeled after libxml-config.
 
-version=1.6.18
+version=1.6.19
 prefix=""
 libdir=""
 libs=""
diff --git a/scripts/libpng.pc.in b/scripts/libpng.pc.in
index d4536c564..8185c5d5a 100644
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@ includedir=@includedir@/libpng16
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.18
+Version: 1.6.19
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
diff --git a/scripts/makefile.cegcc b/scripts/makefile.cegcc
index 98ec5b4f9..1aa58243d 100644
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@
 
 VERMAJ = 1
 VERMIN = 6
-VERMIC = 18
+VERMIC = 19
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
diff --git a/scripts/makefile.linux b/scripts/makefile.linux
index 20193af69..6d45ea198 100644
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 18
+RELEASE = 19
 
 # Shared library names:
 LIBSO=$(LIBNAME).so
diff --git a/scripts/makefile.msys b/scripts/makefile.msys
index c16ec4039..9896761c5 100644
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@ exec_prefix=$(prefix)
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 18
+RELEASE = 19
 
 # Shared library names:
 LIBSO=$(LIBNAME).dll
diff --git a/scripts/makefile.ne12bsd b/scripts/makefile.ne12bsd
index cfcfcd3f2..6cf1fed70 100644
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include/libpng16
 
 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.18
+SHLIB_MINOR=	1.6.19
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.netbsd b/scripts/makefile.netbsd
index 079f708f1..a3b69e0d6 100644
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include
 
 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.18
+SHLIB_MINOR=	1.6.19
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.openbsd b/scripts/makefile.openbsd
index 360efd105..d8824d2e2 100644
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@ LIBDIR=	${PREFIX}/lib
 MANDIR= ${PREFIX}/man/cat
 
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.18
+SHLIB_MINOR=	1.6.19
 
 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
diff --git a/scripts/pnglibconf.dfa b/scripts/pnglibconf.dfa
index 07293ae64..b2b7b4309 100644
--- a/scripts/pnglibconf.dfa
+++ b/scripts/pnglibconf.dfa
@@ -515,9 +515,7 @@ option WRITE_USER_TRANSFORM requires WRITE_TRANSFORMS
 
 option WRITE_INTERLACING requires WRITE
 
-# The following depends, internally, on WEIGHT_SHIFT and COST_SHIFT
-# where are set below.
-
+# Deprecated, will be removed.
 option WRITE_WEIGHTED_FILTER requires WRITE
 
 option WRITE_FLUSH requires WRITE
@@ -668,11 +666,6 @@ setting MAX_GAMMA_8 default 11
 
 setting GAMMA_THRESHOLD_FIXED default 5000
 
-# Scaling factor for filter heuristic weighting calculations
-
-setting WEIGHT_SHIFT default 8
-setting COST_SHIFT default 3
-
 # Precision to use when converting a floating point value to a PNG
 # extension format string in an sCAL chunk (only relevant if the
 # floating point API is enabled)
diff --git a/scripts/pnglibconf.h.prebuilt b/scripts/pnglibconf.h.prebuilt
index 2719f0098..ff5d156a6 100644
--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,10 +1,10 @@
-/* libpng 1.6.18 STANDARD API DEFINITION */
+/* libpng 1.6.19 STANDARD API DEFINITION */
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng version 1.6.18 - July 23, 2015 */
+/* Libpng version 1.6.19 - November 12, 2015 */
 
-/* Copyright (c) 1998-2014 Glenn Randers-Pehrson */
+/* Copyright (c) 1998-2015 Glenn Randers-Pehrson */
 
 /* This code is released under the libpng license. */
 /* For conditions of distribution and use, see the disclaimer */
@@ -185,7 +185,6 @@
 /* end of options */
 /* settings */
 #define PNG_API_RULE 0
-#define PNG_COST_SHIFT 3
 #define PNG_DEFAULT_READ_MACROS 1
 #define PNG_GAMMA_THRESHOLD_FIXED 5000
 #define PNG_IDAT_READ_SIZE PNG_ZBUF_SIZE
@@ -204,7 +203,6 @@
 #define PNG_USER_CHUNK_MALLOC_MAX 8000000
 #define PNG_USER_HEIGHT_MAX 1000000
 #define PNG_USER_WIDTH_MAX 1000000
-#define PNG_WEIGHT_SHIFT 8
 #define PNG_ZBUF_SIZE 8192
 #define PNG_ZLIB_VERNUM 0 /* unknown */
 #define PNG_Z_DEFAULT_COMPRESSION (-1)
diff --git a/scripts/symbols.def b/scripts/symbols.def
index 2ec460514..5d3d53cc4 100644
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.18
+;Version 1.6.19
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng
diff --git a/tests/pngimage-full b/tests/pngimage-full
index f5eb9895e..1198ed05c 100755
--- a/tests/pngimage-full
+++ b/tests/pngimage-full
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngimage --exhaustive --log "${srcdir}/contrib/pngsuite/"*.png
+exec ./pngimage --exhaustive --list-combos --log "${srcdir}/contrib/pngsuite/"*.png
diff --git a/tests/pngimage-quick b/tests/pngimage-quick
index 2d4b5db22..328dc27b5 100755
--- a/tests/pngimage-quick
+++ b/tests/pngimage-quick
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngimage --log "${srcdir}/contrib/pngsuite/"*.png
+exec ./pngimage --list-combos --log "${srcdir}/contrib/pngsuite/"*.png
diff --git a/tests/pngstest b/tests/pngstest
index f5cbdbcae..255ed098f 100755
--- a/tests/pngstest
+++ b/tests/pngstest
@@ -2,12 +2,51 @@
 #
 # Usage:
 #
-#  tests/pngstest pattern
+#  tests/pngstest gamma alpha
 #
-# Runs pngstest on all the contrib/pngsuite/[^x]*${pattern}.png files
-# NOTE: pattern is used to name the temporary files pngstest generates
+# Run ./pngstest on the PNG files in $srcdir/contrib/testpngs which have the
+# given gamma and opacity:
 #
-pattern="$1"
+#  gamma: one of; linear, 1.8, sRGB, none.
+#  alpha: one of; opaque, tRNS, alpha, none.  'none' is equivalent to !alpha
+#
+# NOTE: the temporary files pngstest generates have the base name gamma-alpha to
+# avoid issues with make -j
+#
+gamma="$1"
 shift
-exec ./pngstest --strict --tmpfile "${pattern}" --log ${1+"$@"}\
-   "${srcdir}/contrib/pngsuite/"[a-wyz]*${pattern}".png"
+alpha="$1"
+shift
+exec ./pngstest --tmpfile "${gamma}-${alpha}-" --log ${1+"$@"} $(
+   for f in "${srcdir}/contrib/testpngs/"*.png
+   do
+      g=
+      case "$f" in
+         *-linear[.-]*)
+            test "$gamma" = "linear" && g="$f";;
+
+         *-sRGB[.-]*)
+            test "$gamma" = "sRGB" && g="$f";;
+
+         *-1.8[.-]*)
+            test "$gamma" = "1.8" && g="$f";;
+
+         *)
+            test "$gamma" = "none" && g="$f";;
+      esac
+
+      case "$g" in
+         "")
+            :;;
+
+         *-alpha[-.]*)
+            test "$alpha" = "alpha" && echo "$g";;
+
+         *-tRNS[-.]*)
+            test "$alpha" = "tRNS" -o "$alpha" = "none" && echo "$g";;
+
+         *)
+            test "$alpha" = "opaque" -o "$alpha" = "none" && echo "$g";;
+      esac
+   done
+)
diff --git a/tests/pngstest-0g01 b/tests/pngstest-0g01
deleted file mode 100755
index 4a495ccb8..000000000
--- a/tests/pngstest-0g01
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 0g01
diff --git a/tests/pngstest-0g02 b/tests/pngstest-0g02
deleted file mode 100755
index 1a607c8e1..000000000
--- a/tests/pngstest-0g02
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 0g02
diff --git a/tests/pngstest-0g04 b/tests/pngstest-0g04
deleted file mode 100755
index 595ba01e3..000000000
--- a/tests/pngstest-0g04
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 0g04
diff --git a/tests/pngstest-0g08 b/tests/pngstest-0g08
deleted file mode 100755
index 21a8b4bb4..000000000
--- a/tests/pngstest-0g08
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 0g08
diff --git a/tests/pngstest-0g16 b/tests/pngstest-0g16
deleted file mode 100755
index 0104c37bd..000000000
--- a/tests/pngstest-0g16
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 0g16
diff --git a/tests/pngstest-1.8 b/tests/pngstest-1.8
new file mode 100755
index 000000000..b2ec21bf6
--- /dev/null
+++ b/tests/pngstest-1.8
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" 1.8 none
diff --git a/tests/pngstest-1.8-alpha b/tests/pngstest-1.8-alpha
new file mode 100755
index 000000000..d00596d55
--- /dev/null
+++ b/tests/pngstest-1.8-alpha
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" 1.8 alpha
diff --git a/tests/pngstest-2c08 b/tests/pngstest-2c08
deleted file mode 100755
index 9e0de6f1e..000000000
--- a/tests/pngstest-2c08
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 2c08
diff --git a/tests/pngstest-2c16 b/tests/pngstest-2c16
deleted file mode 100755
index c1b88b04e..000000000
--- a/tests/pngstest-2c16
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 2c16
diff --git a/tests/pngstest-3p01 b/tests/pngstest-3p01
deleted file mode 100755
index 6aeb8d06c..000000000
--- a/tests/pngstest-3p01
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 3p01
diff --git a/tests/pngstest-3p02 b/tests/pngstest-3p02
deleted file mode 100755
index 770a75c0b..000000000
--- a/tests/pngstest-3p02
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 3p02
diff --git a/tests/pngstest-3p04 b/tests/pngstest-3p04
deleted file mode 100755
index 957d6ae34..000000000
--- a/tests/pngstest-3p04
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 3p04
diff --git a/tests/pngstest-3p08 b/tests/pngstest-3p08
deleted file mode 100755
index d0947afde..000000000
--- a/tests/pngstest-3p08
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 3p08
diff --git a/tests/pngstest-4a08 b/tests/pngstest-4a08
deleted file mode 100755
index 2fab57f01..000000000
--- a/tests/pngstest-4a08
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 4a08
diff --git a/tests/pngstest-4a16 b/tests/pngstest-4a16
deleted file mode 100755
index e4ad5aa9a..000000000
--- a/tests/pngstest-4a16
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 4a16
diff --git a/tests/pngstest-6a08 b/tests/pngstest-6a08
deleted file mode 100755
index aa6c03c3d..000000000
--- a/tests/pngstest-6a08
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 6a08
diff --git a/tests/pngstest-6a16 b/tests/pngstest-6a16
deleted file mode 100755
index 545b1b394..000000000
--- a/tests/pngstest-6a16
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec "${srcdir}/tests/pngstest" 6a16
diff --git a/tests/pngstest-error b/tests/pngstest-error
deleted file mode 100755
index ebf3a7b59..000000000
--- a/tests/pngstest-error
+++ /dev/null
@@ -1,14 +0,0 @@
-#!/bin/sh
-code=77 # skipped
-for t in "${srcdir}/contrib/pngsuite/"x*".png"
-do
-   if test "$t" != "${srcdir}/contrib/pngsuite/x*.png"
-   then
-      # not skipped, test it
-      if ./pngstest --strict --tmpfile "error" --log "$@" "$t"
-      then
-         code=0 # oops, success: should not happen!
-      fi
-   fi
-done
-exit $code
diff --git a/tests/pngstest-linear b/tests/pngstest-linear
new file mode 100755
index 000000000..4a5b3fe8c
--- /dev/null
+++ b/tests/pngstest-linear
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" linear none
diff --git a/tests/pngstest-linear-alpha b/tests/pngstest-linear-alpha
new file mode 100755
index 000000000..411421036
--- /dev/null
+++ b/tests/pngstest-linear-alpha
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" linear alpha
diff --git a/tests/pngstest-none b/tests/pngstest-none
new file mode 100755
index 000000000..09ad740b5
--- /dev/null
+++ b/tests/pngstest-none
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" none none
diff --git a/tests/pngstest-none-alpha b/tests/pngstest-none-alpha
new file mode 100755
index 000000000..af6083ff8
--- /dev/null
+++ b/tests/pngstest-none-alpha
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" none alpha
diff --git a/tests/pngstest-sRGB b/tests/pngstest-sRGB
new file mode 100755
index 000000000..d8460812c
--- /dev/null
+++ b/tests/pngstest-sRGB
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" sRGB none
diff --git a/tests/pngstest-sRGB-alpha b/tests/pngstest-sRGB-alpha
new file mode 100755
index 000000000..f1e57d339
--- /dev/null
+++ b/tests/pngstest-sRGB-alpha
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec "${srcdir}/tests/pngstest" sRGB alpha
diff --git a/tests/pngunknown-IDAT b/tests/pngunknown-IDAT
index 71d915a9c..8e7281aa8 100755
--- a/tests/pngunknown-IDAT
+++ b/tests/pngunknown-IDAT
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown default=discard IDAT=save "${srcdir}/pngtest.png"
+exec ./pngunknown --strict default=discard IDAT=save "${srcdir}/pngtest.png"
diff --git a/tests/pngunknown-discard b/tests/pngunknown-discard
index f1f02d4c7..c96dab370 100755
--- a/tests/pngunknown-discard
+++ b/tests/pngunknown-discard
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown default=discard "${srcdir}/pngtest.png"
+exec ./pngunknown --strict default=discard "${srcdir}/pngtest.png"
diff --git a/tests/pngunknown-if-safe b/tests/pngunknown-if-safe
index 7c52824f8..31a4954fb 100755
--- a/tests/pngunknown-if-safe
+++ b/tests/pngunknown-if-safe
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown default=if-safe "${srcdir}/pngtest.png"
+exec ./pngunknown --strict default=if-safe "${srcdir}/pngtest.png"
diff --git a/tests/pngunknown-sAPI b/tests/pngunknown-sAPI
index e087ef25a..4317b1847 100755
--- a/tests/pngunknown-sAPI
+++ b/tests/pngunknown-sAPI
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown bKGD=save cHRM=save gAMA=save all=discard iCCP=save sBIT=save sRGB=save "${srcdir}/pngtest.png"
+exec ./pngunknown --strict bKGD=save cHRM=save gAMA=save all=discard iCCP=save sBIT=save sRGB=save "${srcdir}/pngtest.png"
diff --git a/tests/pngunknown-sTER b/tests/pngunknown-sTER
index 1b945dc34..59c5ecd54 100755
--- a/tests/pngunknown-sTER
+++ b/tests/pngunknown-sTER
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown sTER=if-safe "${srcdir}/pngtest.png"
+exec ./pngunknown --strict sTER=if-safe "${srcdir}/pngtest.png"
diff --git a/tests/pngunknown-save b/tests/pngunknown-save
index ae849308c..21412c42a 100755
--- a/tests/pngunknown-save
+++ b/tests/pngunknown-save
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown default=save "${srcdir}/pngtest.png"
+exec ./pngunknown --strict default=save "${srcdir}/pngtest.png"
diff --git a/tests/pngunknown-vpAg b/tests/pngunknown-vpAg
index 396c6e40d..04f07b69a 100755
--- a/tests/pngunknown-vpAg
+++ b/tests/pngunknown-vpAg
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngunknown vpAg=if-safe "${srcdir}/pngtest.png"
+exec ./pngunknown --strict vpAg=if-safe "${srcdir}/pngtest.png"
diff --git a/tests/pngvalid-gamma-16-to-8 b/tests/pngvalid-gamma-16-to-8
index b32233829..074945d31 100755
--- a/tests/pngvalid-gamma-16-to-8
+++ b/tests/pngvalid-gamma-16-to-8
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-16-to-8
+exec ./pngvalid --strict --gamma-16-to-8
diff --git a/tests/pngvalid-gamma-alpha-mode b/tests/pngvalid-gamma-alpha-mode
index ed04fa511..b16e8abc4 100755
--- a/tests/pngvalid-gamma-alpha-mode
+++ b/tests/pngvalid-gamma-alpha-mode
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-alpha-mode
+exec ./pngvalid --strict --gamma-alpha-mode
diff --git a/tests/pngvalid-gamma-background b/tests/pngvalid-gamma-background
index 658e5fe4d..3dbf58d8a 100755
--- a/tests/pngvalid-gamma-background
+++ b/tests/pngvalid-gamma-background
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-background
+exec ./pngvalid --strict --gamma-background
diff --git a/tests/pngvalid-gamma-expand16-alpha-mode b/tests/pngvalid-gamma-expand16-alpha-mode
index bdda566a0..4fa10bde2 100755
--- a/tests/pngvalid-gamma-expand16-alpha-mode
+++ b/tests/pngvalid-gamma-expand16-alpha-mode
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-alpha-mode --expand16
+exec ./pngvalid --strict --gamma-alpha-mode --expand16
diff --git a/tests/pngvalid-gamma-expand16-background b/tests/pngvalid-gamma-expand16-background
index f993c21ae..ad9a91762 100755
--- a/tests/pngvalid-gamma-expand16-background
+++ b/tests/pngvalid-gamma-expand16-background
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-background --expand16
+exec ./pngvalid --strict --gamma-background --expand16
diff --git a/tests/pngvalid-gamma-expand16-transform b/tests/pngvalid-gamma-expand16-transform
index f462534e8..5fd1f280b 100755
--- a/tests/pngvalid-gamma-expand16-transform
+++ b/tests/pngvalid-gamma-expand16-transform
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-transform --expand16
+exec ./pngvalid --strict --gamma-transform --expand16
diff --git a/tests/pngvalid-gamma-sbit b/tests/pngvalid-gamma-sbit
index aa82fe04f..6ca08e9e3 100755
--- a/tests/pngvalid-gamma-sbit
+++ b/tests/pngvalid-gamma-sbit
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-sbit
+exec ./pngvalid --strict --gamma-sbit
diff --git a/tests/pngvalid-gamma-threshold b/tests/pngvalid-gamma-threshold
index 2cfca9146..3fe4edf77 100755
--- a/tests/pngvalid-gamma-threshold
+++ b/tests/pngvalid-gamma-threshold
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-threshold
+exec ./pngvalid --strict --gamma-threshold
diff --git a/tests/pngvalid-gamma-transform b/tests/pngvalid-gamma-transform
index a71ab4d5e..3fa62c688 100755
--- a/tests/pngvalid-gamma-transform
+++ b/tests/pngvalid-gamma-transform
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --gamma-transform
+exec ./pngvalid --strict --gamma-transform
diff --git a/tests/pngvalid-progressive-interlace-size b/tests/pngvalid-progressive-interlace-size
deleted file mode 100755
index a31b28355..000000000
--- a/tests/pngvalid-progressive-interlace-size
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec ./pngvalid --size --progressive-read
diff --git a/tests/pngvalid-progressive-interlace-standard b/tests/pngvalid-progressive-interlace-standard
index 59042eb17..a8cdf9e1a 100755
--- a/tests/pngvalid-progressive-interlace-standard
+++ b/tests/pngvalid-progressive-interlace-standard
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --standard --progressive-read --interlace
+exec ./pngvalid --strict --standard --progressive-read --interlace
diff --git a/tests/pngvalid-progressive-interlace-transform b/tests/pngvalid-progressive-interlace-transform
deleted file mode 100755
index edf9a8a79..000000000
--- a/tests/pngvalid-progressive-interlace-transform
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec ./pngvalid --transform
diff --git a/tests/pngvalid-progressive-size b/tests/pngvalid-progressive-size
new file mode 100755
index 000000000..868d6dcc3
--- /dev/null
+++ b/tests/pngvalid-progressive-size
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec ./pngvalid --strict --size --progressive-read
diff --git a/tests/pngvalid-progressive-standard b/tests/pngvalid-progressive-standard
index aa1b4b4db..bf7e5c1c2 100755
--- a/tests/pngvalid-progressive-standard
+++ b/tests/pngvalid-progressive-standard
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --standard --progressive-read
+exec ./pngvalid --strict --standard --progressive-read
diff --git a/tests/pngvalid-standard b/tests/pngvalid-standard
index aa1b4b4db..a89b88424 100755
--- a/tests/pngvalid-standard
+++ b/tests/pngvalid-standard
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec ./pngvalid --standard --progressive-read
+exec ./pngvalid --strict --standard
diff --git a/tests/pngvalid-transform b/tests/pngvalid-transform
new file mode 100755
index 000000000..c7536aeb8
--- /dev/null
+++ b/tests/pngvalid-transform
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec ./pngvalid --strict --transform