[libpng16] Imported from libpng-1.6.18beta01.tar

have been combined with PNG_SET_USER_LIMITS_SUPPORTED (resolves
bug report by Andrew Church).

ANNOUNCE

@@ -1,4 +1,4 @@
-Libpng 1.6.17rc04 - March 16, 2015
+Libpng 1.6.18beta01 - April 1, 2015
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -8,82 +8,30 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   1.6.17rc04.tar.xz (LZMA-compressed, recommended)
-   1.6.17rc04.tar.gz
+   1.6.18beta01.tar.xz (LZMA-compressed, recommended)
+   1.6.18beta01.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lp1617r04.7z  (LZMA-compressed, recommended)
-   lp1617r04.zip
+   lp1618b01.7z  (LZMA-compressed, recommended)
+   lp1618b01.zip
 
 Other information:
 
-   1.6.17rc04-README.txt
-   1.6.17rc04-LICENSE.txt
-   libpng-1.6.17rc04-*.asc (armored detached GPG signatures)
+   1.6.18beta01-README.txt
+   1.6.18beta01-LICENSE.txt
+   libpng-1.6.18beta01-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.6.16):
+Changes since the last public release (1.6.17):
 
-Version 1.6.17beta01 [January 29, 2015]
-  Removed duplicate PNG_SAFE_LIMITS_SUPPORTED handling from pngconf.h
-  Corrected the width limit calculation in png_check_IHDR().
-  Removed user limits from pngfix. Also pass NULL pointers to
-    png_read_row to skip the unnecessary row de-interlace stuff.
-  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().
-  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.
-  Added #ifndef __COVERITY__ where needed in png.c, pngrutil.c and
-    pngset.c to avoid warnings about dead code.
-  Added "& 0xff" to many instances of expressions that are typecast
-    to (png_byte), to avoid Coverity gripes.
-
-Version 1.6.17beta02 [February 7, 2015]
-  Work around one more Coverity-scan dead-code warning.
-  Do not build png_product2() when it is unused.
-
-Version 1.6.17beta03 [February 17, 2015]
-  Display user limits in the output from pngtest.
-  Eliminated the PNG_SAFE_LIMITS macro and restored the 1-million-column
-    and 1-million-row default limits in pnglibconf.dfa, that can be reset
-    by the user at build time or run time.  This provides a more robust
-    defense against DOS and as-yet undiscovered overflows.
-
-Version 1.6.17beta04 [February 21, 2015]
-  Added PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED macro, on by default.
-  Allow user to call png_get_IHDR() with NULL arguments (Reuben Hawkins).
-  Rebuilt configure scripts with automake-1.15 and libtool-2.4.6
-
-Version 1.6.17beta05 [February 25, 2015]
-  Restored compiling of png_reciprocal2 with PNG_NO_16BIT.
-
-Version 1.6.17beta06 [February 27, 2015]
-  Moved png_set_filter() prototype into a PNG_WRITE_SUPPORTED block
-    of png.h.
-  Avoid runtime checks when converting integer to png_byte with
-    Visual Studio (Sergey Kosarevsky)
-
-Version 1.6.17rc01 [March 4, 2015]
-  No changes.
-
-Version 1.6.17rc02 [March 9, 2015]
-  Removed some comments that the configure script did not handle
-    properly from scripts/pnglibconf.dfa and pnglibconf.h.prebuilt.
-  Free the unknown_chunks structure even when it contains no data.
-
-Version 1.6.17rc03 [March 12, 2015]
-  Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
-    for consistency, and remove some useless tests (Alexey Petruchik).
-
-Version 1.6.17rc04 [March 16, 2015]
-  Remove pnglibconf.h, pnglibconf.c, and pnglibconf.out instead of
-    pnglibconf.* in "make clean" (Cosmin).
-  Fix bug in calculation of maxbits, in png_write_sBIT, introduced
-    in libpng-1.6.17beta01 (John Bowler).
+Version 1.6.18beta01 [April 1, 2015]
+  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.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -5186,6 +5186,33 @@ Version 1.6.17rc04 [March 16, 2015]
   Fix bug in calculation of maxbits, in png_write_sBIT, introduced
     in libpng-1.6.17beta01 (John Bowler).
 
+Version 1.6.17rc05 [March 21, 2015]
+  Define PNG_FILTER_* and PNG_FILTER_VALUE_* in png.h even when WRITE
+    is not supported (John Bowler).  This fixes an error introduced in
+    libpng-1.6.17beta06.
+  Reverted "& 0xff" additions of version 1.6.17beta01. Libpng passes
+    the Coverity scan without them.
+
+Version 1.6.17rc06 [March 23, 2015]
+  Remove pnglibconf.dfn and pnglibconf.pre with "make clean".
+  Reformatted some "&0xff" instances to "& 0xff".
+  Fixed simplified 8-bit-linear to sRGB alpha. The calculated alpha
+    value was wrong.  It's not clear if this affected the final stored
+    value; in the obvious code path the upper and lower 8-bits of the
+    alpha value were identical and the alpha was truncated to 8-bits
+    rather than dividing by 257 (John Bowler).
+
+Version 1.6.17 [March 26, 2015]
+  No changes.
+
+Version 1.6.18beta01 [April 1, 2015]
+  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.
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement

CMakeLists.txt

@@ -16,7 +16,7 @@ enable_testing()
 
 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 17)
+set(PNGLIB_RELEASE 18)
 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}.1.6.17rc04
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.18beta01
     VERSION 16.${PNGLIB_RELEASE}.0
     SOVERSION 16
     CLEAN_DIRECT_OUTPUT 1)

LICENSE

@@ -10,7 +10,7 @@ this sentence.
 
 This code is released under the libpng license.
 
-libpng versions 1.2.6, August 15, 2004, through 1.6.17rc04, March 16, 2015, are
+libpng versions 1.2.6, August 15, 2004, through 1.6.18beta01, April 1, 2015, are
 Copyright (c) 2004, 2006-2015 Glenn Randers-Pehrson, and are
 distributed according to the same disclaimer and license as libpng-1.2.5
 with the following individual added to the list of Contributing Authors
@@ -108,4 +108,4 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-March 16, 2015
+April 1, 2015

Makefile.am

@@ -134,7 +134,7 @@ SCRIPT_CLEANFILES=scripts/*.out scripts/*.chk
 CLEANFILES= *.tf? pngout.png libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc \
 	libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config libpng.vers libpng.sym \
 	check.new pnglibconf.h pngprefix.h symbols.new pngtest-log.txt \
-	pnglibconf.out pnglibconf.c \
+	pnglibconf.out pnglibconf.c pnglibconf.pre pnglibconf.dfn \
 	$(SCRIPT_CLEANFILES)
 
 MAINTAINERCLEANFILES = Makefile.in aclocal.m4 config.guess config.h.in \

README

@@ -1,4 +1,4 @@
-README for libpng version 1.6.17rc04 - March 16, 2015 (shared library 16.0)
+README for libpng version 1.6.18beta01 - April 1, 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.

autogen.sh

@@ -73,8 +73,9 @@ done
 # present bad things are happening.
 #
 # The autotools generated files:
-libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in\
-   config.sub configure depcomp install-sh ltmain.sh missing test-driver"
+libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
+   config.h.in~ 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):

configure.ac

@@ -18,7 +18,7 @@ AC_PREREQ([2.68])
 
 dnl Version number stuff here:
 
-AC_INIT([libpng],[1.6.17rc04],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.18beta01],[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=1.6.17rc04
+PNGLIB_VERSION=1.6.18beta01
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=17
+PNGLIB_RELEASE=18
 
 dnl End of version number stuff
 

contrib/libtests/pngvalid.c

@@ -258,7 +258,7 @@ make_four_random_bytes(png_uint_32* seed, png_bytep bytes)
    make_random_bytes(seed, bytes, 4);
 }
 
-#ifdef PNG_READ_SUPPORTED
+#if defined PNG_READ_SUPPORTED || defined PNG_WRITE_tRNS_SUPPORTED
 static void
 randomize(void *pv, size_t size)
 {
@@ -267,7 +267,9 @@ randomize(void *pv, size_t size)
 }
 
 #define RANDOMIZE(this) randomize(&(this), sizeof (this))
+#endif /* READ || WRITE_tRNS */
 
+#ifdef PNG_READ_SUPPORTED
 static unsigned int
 random_mod(unsigned int max)
 {
@@ -295,7 +297,8 @@ random_choice(void)
 /* A numeric ID based on PNG file characteristics.  The 'do_interlace' field
  * simply records whether pngvalid did the interlace itself or whether it
  * was done by libpng.  Width and height must be less than 256.  'palette' is an
- * index of the palette to use for formats with a palette (0 otherwise.)
+ * index of the palette to use for formats with a palette otherwise a boolean
+ * indicating if a tRNS chunk was generated.
  */
 #define FILEID(col, depth, palette, interlace, width, height, do_interlace) \
    ((png_uint_32)((col) + ((depth)<<3) + ((palette)<<8) + ((interlace)<<13) + \
@@ -316,12 +319,16 @@ standard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type,
     png_uint_32 w, png_uint_32 h, int do_interlace)
 {
    pos = safecat(buffer, bufsize, pos, colour_types[colour_type]);
-   if (npalette > 0)
+   if (colour_type == 3) /* must have a palette */
    {
       pos = safecat(buffer, bufsize, pos, "[");
       pos = safecatn(buffer, bufsize, pos, npalette);
       pos = safecat(buffer, bufsize, pos, "]");
    }
+
+   else if (npalette != 0)
+      pos = safecat(buffer, bufsize, pos, "+tRNS");
+
    pos = safecat(buffer, bufsize, pos, " ");
    pos = safecatn(buffer, bufsize, pos, bit_depth);
    pos = safecat(buffer, bufsize, pos, " bit");
@@ -378,25 +385,32 @@ standard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id)
 
 static int
 next_format(png_bytep colour_type, png_bytep bit_depth,
-   unsigned int* palette_number, int no_low_depth_gray)
+   unsigned int* palette_number, int low_depth_gray, int tRNS)
 {
    if (*bit_depth == 0)
    {
       *colour_type = 0;
-      if (no_low_depth_gray)
-         *bit_depth = 8;
-      else
+      if (low_depth_gray)
          *bit_depth = 1;
+      else
+         *bit_depth = 8;
       *palette_number = 0;
       return 1;
    }
 
-   if (*colour_type == 3)
+   if  (*colour_type < 4/*no alpha channel*/)
    {
-      /* Add multiple palettes for colour type 3. */
-      if (++*palette_number < PALETTE_COUNT(*bit_depth))
+      /* Add multiple palettes for colour type 3, one image with tRNS
+       * and one without for other non-alpha formats:
+       */
+      unsigned int pn = ++*palette_number;
+      png_byte ct = *colour_type;
+
+      if (((ct == 0/*GRAY*/ || ct/*RGB*/ == 2) && tRNS && pn < 2) ||
+          (ct == 3/*PALETTE*/ && pn < PALETTE_COUNT(*bit_depth)))
          return 1;
 
+      /* No: next bit depth */
       *palette_number = 0;
    }
 
@@ -1959,6 +1973,7 @@ typedef struct png_modifier
 
    /* Run tests on reading with a combination of transforms, */
    unsigned int             test_transform :1;
+   unsigned int             test_tRNS :1; /* Includes tRNS images */
 
    /* When to use the use_input_precision option, this controls the gamma
     * validation code checks.  If set any value that is within the transformed
@@ -1990,6 +2005,16 @@ 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
+    * gamma images in some cases because of gross inaccuracies in the grayscale
+    * gamma handling for low bit depth.
+    */
+   unsigned int             test_lbg :1;
+   unsigned int             test_lbg_gamma_threshold :1;
+   unsigned int             test_lbg_gamma_transform :1;
+   unsigned int             test_lbg_gamma_sbit :1;
+   unsigned int             test_lbg_gamma_composition :1;
+
    unsigned int             log :1;   /* Log max error */
 
    /* Buffer information, the buffer size limits the size of the chunks that can
@@ -2042,6 +2067,11 @@ modifier_init(png_modifier *pm)
    pm->test_standard = 0;
    pm->test_size = 0;
    pm->test_transform = 0;
+#  ifdef PNG_WRITE_tRNS_SUPPORTED
+      pm->test_tRNS = 1;
+#  else
+      pm->test_tRNS = 0;
+#  endif
    pm->use_input_precision = 0;
    pm->use_input_precision_sbit = 0;
    pm->use_input_precision_16to8 = 0;
@@ -2054,6 +2084,11 @@ modifier_init(png_modifier *pm)
    pm->test_gamma_background = 0;
    pm->test_gamma_alpha_mode = 0;
    pm->test_gamma_expand16 = 0;
+   pm->test_lbg = 1;
+   pm->test_lbg_gamma_threshold = 1;
+   pm->test_lbg_gamma_transform = 1;
+   pm->test_lbg_gamma_sbit = 1;
+   pm->test_lbg_gamma_composition = 1;
    pm->test_exhaustive = 0;
    pm->log = 0;
 
@@ -3192,6 +3227,45 @@ 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)
+{
+   /* 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
+    * that the test image contains all the gray values.  For RGB we need more
+    * method as only 65536 different RGB values are generated.
+    */
+   png_color_16 tRNS;
+   const png_uint_16 mask = (png_uint_16)((1U << bit_depth)-1);
+
+   RANDOMIZE(tRNS);
+
+   if (colour_type & 2/*RGB*/)
+   {
+      if (bit_depth == 8)
+      {
+         tRNS.blue = tRNS.red ^ tRNS.green;
+         tRNS.red &= mask;
+         tRNS.green &= mask;
+         tRNS.blue &= mask;
+      }
+
+      else /* bit_depth == 16 */
+      {
+         tRNS.green = (png_uint_16)(tRNS.red * 257);
+         tRNS.blue = (png_uint_16)(tRNS.green * 17);
+      }
+   }
+
+   else
+      tRNS.gray &= mask;
+
+   png_set_tRNS(pp, pi, NULL, 0, &tRNS);
+}
+#endif
+
 /* The number of passes is related to the interlace type. There was no libpng
  * API to determine this prior to 1.5, so we need an inquiry function:
  */
@@ -3525,6 +3599,11 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
       if (colour_type == 3) /* palette */
          init_standard_palette(ps, pp, pi, 1U << bit_depth, 1/*do tRNS*/);
 
+#     ifdef PNG_WRITE_tRNS_SUPPORTED
+         else if (palette_number)
+            set_random_tRNS(pp, pi, colour_type, bit_depth);
+#     endif
+
       png_write_info(pp, pi);
 
       if (png_get_rowbytes(pp, pi) !=
@@ -3598,19 +3677,20 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
 }
 
 static void
-make_transform_images(png_store *ps)
+make_transform_images(png_modifier *pm)
 {
    png_byte colour_type = 0;
    png_byte bit_depth = 0;
    unsigned int palette_number = 0;
 
    /* This is in case of errors. */
-   safecat(ps->test, sizeof ps->test, 0, "make standard images");
+   safecat(pm->this.test, sizeof pm->this.test, 0, "make standard images");
 
    /* Use next_format to enumerate all the combinations we test, including
-    * generating multiple low bit depth palette images.
+    * generating multiple low bit depth palette images. Non-A images (palette
+    * and direct) are created with and without tRNS chunks.
     */
-   while (next_format(&colour_type, &bit_depth, &palette_number, 0))
+   while (next_format(&colour_type, &bit_depth, &palette_number, 1, 1))
    {
       int interlace_type;
 
@@ -3621,7 +3701,7 @@ make_transform_images(png_store *ps)
 
          standard_name(name, sizeof name, 0, colour_type, bit_depth,
             palette_number, interlace_type, 0, 0, 0);
-         make_transform_image(ps, colour_type, bit_depth, palette_number,
+         make_transform_image(&pm->this, colour_type, bit_depth, palette_number,
             interlace_type, name);
       }
    }
@@ -4287,6 +4367,7 @@ typedef struct standard_display
    size_t      cbRow;          /* Bytes in a row of the output image */
    int         do_interlace;   /* Do interlacing internally */
    int         is_transparent; /* Transparency information was present. */
+   int         has_tRNS;       /* color type GRAY or RGB with a tRNS chunk. */
    int         speed;          /* Doing a speed test */
    int         use_update_info;/* Call update_info, not start_image */
    struct
@@ -4619,14 +4700,14 @@ standard_info_part1(standard_display *dp, png_structp pp, png_infop pi)
          case 0:
             dp->transparent.red = dp->transparent.green = dp->transparent.blue =
                trans_color->gray;
-            dp->is_transparent = 1;
+            dp->has_tRNS = 1;
             break;
 
          case 2:
             dp->transparent.red = trans_color->red;
             dp->transparent.green = trans_color->green;
             dp->transparent.blue = trans_color->blue;
-            dp->is_transparent = 1;
+            dp->has_tRNS = 1;
             break;
 
          case 3:
@@ -5518,7 +5599,7 @@ 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 = 8;
+            this->bit_depth = this->sample_depth = 8;
 
          if (this->have_tRNS)
          {
@@ -5553,9 +5634,11 @@ image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
                this->alphaf = 0;
             else
                this->alphaf = 1;
-
-            this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
          }
+         else
+            this->alphaf = 1;
+
+         this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
       }
 
       /* The error in the alpha is zero and the sBIT value comes from the
@@ -5848,8 +5931,9 @@ transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
    /* If png_set_filler is in action then fake the output color type to include
     * an alpha channel where appropriate.
     */
-   if (dp->output_bit_depth >= 8 && (dp->output_colour_type == PNG_COLOR_TYPE_RGB ||
-       dp->output_colour_type == PNG_COLOR_TYPE_GRAY) && dp->this.filler)
+   if (dp->output_bit_depth >= 8 &&
+       (dp->output_colour_type == PNG_COLOR_TYPE_RGB ||
+        dp->output_colour_type == PNG_COLOR_TYPE_GRAY) && dp->this.filler)
        dp->output_colour_type |= 4;
 
    /* Validate the combination of colour type and bit depth that we are getting
@@ -6372,6 +6456,13 @@ image_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this,
    transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_tRNS_to_alpha(pp);
+
+   /* If there was a tRNS chunk that would get expanded and add an alpha
+    * channel is_transparent must be updated:
+    */
+   if (that->this.has_tRNS)
+      that->this.is_transparent = 1;
+
    this->next->set(this->next, that, pp, pi);
 }
 
@@ -6430,6 +6521,7 @@ image_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_gray_to_rgb(pp);
+   /* NOTE: this doesn't result in tRNS expansion. */
    this->next->set(this->next, that, pp, pi);
 }
 
@@ -6489,6 +6581,10 @@ image_transform_png_set_expand_set(PNG_CONST image_transform *this,
     transform_display *that, png_structp pp, png_infop pi)
 {
    png_set_expand(pp);
+
+   if (that->this.has_tRNS)
+      that->this.is_transparent = 1;
+
    this->next->set(this->next, that, pp, pi);
 }
 
@@ -6539,6 +6635,7 @@ image_transform_png_set_expand_gray_1_2_4_to_8_set(
     png_infop pi)
 {
    png_set_expand_gray_1_2_4_to_8(pp);
+   /* NOTE: don't expect this to expand tRNS */
    this->next->set(this->next, that, pp, pi);
 }
 
@@ -6570,6 +6667,11 @@ image_transform_png_set_expand_16_set(PNG_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;
+
    this->next->set(this->next, that, pp, pi);
 }
 
@@ -6940,14 +7042,14 @@ image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
           * When DIGITIZE is set because a pre-1.7 version of libpng is being
           * tested allow a bigger slack.
           *
-          * NOTE: this magic number was determined by experiment to be 1.25.
-          * There's no great merit to the value below, however it only affects
-          * the limit used for checking for internal calculation errors, not
-          * the actual limit imposed by pngvalid on the output errors.
+          * NOTE: this magic number was determined by experiment to be about
+          * 1.263.  There's no great merit to the value below, however it only
+          * 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(
 #        if DIGITIZE
-            1.25
+            1.3
 #        else
             1.0
 #        endif
@@ -7111,7 +7213,8 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
          const unsigned int sample_depth = that->sample_depth;
          const unsigned int calc_depth = (pm->assume_16_bit_calculations ? 16 :
             sample_depth);
-         const unsigned int gamma_depth = (sample_depth == 16 ? 16 :
+         const unsigned int gamma_depth = (sample_depth == 16 ?
+            PNG_MAX_GAMMA_8 :
             (pm->assume_16_bit_calculations ? PNG_MAX_GAMMA_8 : sample_depth));
          int isgray;
          double r, g, b;
@@ -7125,56 +7228,73 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
           * will be identical after this operation if there is only one
           * transform, feel free to delete the png_error checks on this below in
           * the future (this is just me trying to ensure it works!)
+          *
+          * Interval arithmetic is exact, but to implement it it must be
+          * possible to control the floating point implementation rounding mode.
+          * This cannot be done in ANSI-C, so instead I reduce the 'lo' values
+          * by DBL_EPSILON and increase the 'hi' values by the same.
           */
+#        define DD(v,d,r) (digitize(v*(1-DBL_EPSILON), d, r) * (1-DBL_EPSILON))
+#        define DU(v,d,r) (digitize(v*(1+DBL_EPSILON), d, r) * (1+DBL_EPSILON))
+
          r = rlo = rhi = that->redf;
          rlo -= that->rede;
-         rlo = digitize(rlo, calc_depth, 1/*round*/);
+         rlo = DD(rlo, calc_depth, 1/*round*/);
          rhi += that->rede;
-         rhi = digitize(rhi, calc_depth, 1/*round*/);
+         rhi = DU(rhi, calc_depth, 1/*round*/);
 
          g = glo = ghi = that->greenf;
          glo -= that->greene;
-         glo = digitize(glo, calc_depth, 1/*round*/);
+         glo = DD(glo, calc_depth, 1/*round*/);
          ghi += that->greene;
-         ghi = digitize(ghi, calc_depth, 1/*round*/);
+         ghi = DU(ghi, calc_depth, 1/*round*/);
 
          b = blo = bhi = that->bluef;
          blo -= that->bluee;
-         blo = digitize(blo, calc_depth, 1/*round*/);
+         blo = DD(blo, calc_depth, 1/*round*/);
          bhi += that->greene;
-         bhi = digitize(bhi, calc_depth, 1/*round*/);
+         bhi = DU(bhi, calc_depth, 1/*round*/);
 
          isgray = r==g && g==b;
 
          if (data.gamma != 1)
          {
             PNG_CONST double power = 1/data.gamma;
-            PNG_CONST double abse = calc_depth == 16 ? .5/65535 : .5/255;
+            PNG_CONST double abse = .5/(sample_depth == 16 ? 65535 : 255);
 
-            /* 'abse' is the absolute error permitted in linear calculations. It
-             * is used here to capture the error permitted in the handling
-             * (undoing) of the gamma encoding.  Once again digitization occurs
-             * to handle the upper and lower bounds of the values.  This is
-             * where the real errors are introduced.
+            /* If a gamma calculation is done it is done using lookup tables of
+             * precision gamma_depth, so the already digitized value above may
+             * need to be further digitized here.
              */
+            if (gamma_depth != calc_depth)
+            {
+               rlo = DD(rlo, gamma_depth, 0/*truncate*/);
+               rhi = DU(rhi, gamma_depth, 0/*truncate*/);
+               glo = DD(glo, gamma_depth, 0/*truncate*/);
+               ghi = DU(ghi, gamma_depth, 0/*truncate*/);
+               blo = DD(blo, gamma_depth, 0/*truncate*/);
+               bhi = DU(bhi, gamma_depth, 0/*truncate*/);
+            }
+
+            /* 'abse' is the error in the gamma table calculation itself. */
             r = pow(r, power);
-            rlo = digitize(pow(rlo, power)-abse, calc_depth, 1);
-            rhi = digitize(pow(rhi, power)+abse, calc_depth, 1);
+            rlo = DD(pow(rlo, power)-abse, calc_depth, 1);
+            rhi = DU(pow(rhi, power)+abse, calc_depth, 1);
 
             g = pow(g, power);
-            glo = digitize(pow(glo, power)-abse, calc_depth, 1);
-            ghi = digitize(pow(ghi, power)+abse, calc_depth, 1);
+            glo = DD(pow(glo, power)-abse, calc_depth, 1);
+            ghi = DU(pow(ghi, power)+abse, calc_depth, 1);
 
             b = pow(b, power);
-            blo = digitize(pow(blo, power)-abse, calc_depth, 1);
-            bhi = digitize(pow(bhi, power)+abse, calc_depth, 1);
+            blo = DD(pow(blo, power)-abse, calc_depth, 1);
+            bhi = DU(pow(bhi, power)+abse, calc_depth, 1);
          }
 
          /* Now calculate the actual gray values.  Although the error in the
           * coefficients depends on whether they were specified on the command
           * line (in which case truncation to 15 bits happened) or not (rounding
           * was used) the maxium error in an individual coefficient is always
-          * 1/32768, because even in the rounding case the requirement that
+          * 2/32768, because even in the rounding case the requirement that
           * coefficients add up to 32768 can cause a larger rounding error.
           *
           * The only time when rounding doesn't occur in 1.5.5 and later is when
@@ -7185,19 +7305,19 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
 
          {
             PNG_CONST int do_round = data.gamma != 1 || calc_depth == 16;
-            PNG_CONST double ce = 1. / 32768;
+            PNG_CONST double ce = 2. / 32768;
 
-            graylo = digitize(rlo * (data.red_coefficient-ce) +
+            graylo = DD(rlo * (data.red_coefficient-ce) +
                glo * (data.green_coefficient-ce) +
-               blo * (data.blue_coefficient-ce), gamma_depth, do_round);
-            if (graylo <= 0)
-               graylo = 0;
+               blo * (data.blue_coefficient-ce), calc_depth, do_round);
+            if (graylo > gray) /* always accept the right answer */
+               graylo = gray;
 
-            grayhi = digitize(rhi * (data.red_coefficient+ce) +
+            grayhi = DU(rhi * (data.red_coefficient+ce) +
                ghi * (data.green_coefficient+ce) +
-               bhi * (data.blue_coefficient+ce), gamma_depth, do_round);
-            if (grayhi >= 1)
-               grayhi = 1;
+               bhi * (data.blue_coefficient+ce), calc_depth, do_round);
+            if (grayhi < gray)
+               grayhi = gray;
          }
 
          /* And invert the gamma. */
@@ -7205,11 +7325,25 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
          {
             PNG_CONST double power = data.gamma;
 
+            /* And this happens yet again, shifting the values once more. */
+            if (gamma_depth != sample_depth)
+            {
+               rlo = DD(rlo, gamma_depth, 0/*truncate*/);
+               rhi = DU(rhi, gamma_depth, 0/*truncate*/);
+               glo = DD(glo, gamma_depth, 0/*truncate*/);
+               ghi = DU(ghi, gamma_depth, 0/*truncate*/);
+               blo = DD(blo, gamma_depth, 0/*truncate*/);
+               bhi = DU(bhi, gamma_depth, 0/*truncate*/);
+            }
+
             gray = pow(gray, power);
-            graylo = digitize(pow(graylo, power), sample_depth, 1);
-            grayhi = digitize(pow(grayhi, power), sample_depth, 1);
+            graylo = DD(pow(graylo, power), sample_depth, 1);
+            grayhi = DU(pow(grayhi, power), sample_depth, 1);
          }
 
+#        undef DD
+#        undef DU
+
          /* Now the error can be calculated.
           *
           * If r==g==b because there is no overall gamma correction libpng
@@ -7260,16 +7394,28 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
          {
             /* 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
-             * built in 1/32768 error in the coefficients because they only have
-             * 15 bits and are adjusted to make sure they add up to 32768, so
-             * the result may have an additional error up to 1/32768.  (Note
-             * that adding the 1/32768 here avoids needing to increase the
-             * global error limits to take this into account.)
+             * built in error in the coefficients because they only have 15 bits
+             * and are adjusted to make sure they add up to 32768.  This
+             * involves a integer calculation with truncation of the form:
+             *
+             *     ((int)(coefficient * 100000) * 32768)/100000
+             *
+             * This is done to the red and green coefficients (the ones
+             * provided to the API) then blue is calculated from them so the
+             * result adds up to 32768.  In the worst case this can result in
+             * a -1 error in red and green and a +2 error in blue.  Consequently
+             * the worst case in the calculation below is 2/32768 error.
+             *
+             * TODO: consider fixing this in libpng by rounding the calculation
+             * limiting the error to 1/32768.
+             *
+             * Handling this by adding 2/32768 here avoids needing to increase
+             * the global error limits to take this into account.)
              */
             gray = r * data.red_coefficient + g * data.green_coefficient +
                b * data.blue_coefficient;
             err = re * data.red_coefficient + ge * data.green_coefficient +
-               be * data.blue_coefficient + 1./32768 + gray * 5 * DBL_EPSILON;
+               be * data.blue_coefficient + 2./32768 + gray * 5 * DBL_EPSILON;
          }
 
          else
@@ -7304,7 +7450,7 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
              * previously added input quantization error at this point.
              */
             gray = r * data.red_coefficient + g * data.green_coefficient +
-               b * data.blue_coefficient - 1./32768 - out_qe;
+               b * data.blue_coefficient - 2./32768 - out_qe;
             if (gray <= 0)
                gray = 0;
             else
@@ -7314,7 +7460,7 @@ image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
             }
 
             grayhi = rhi * data.red_coefficient + ghi * data.green_coefficient +
-               bhi * data.blue_coefficient + 1./32768 + out_qe;
+               bhi * data.blue_coefficient + 2./32768 + out_qe;
             grayhi *= (1 + 6 * DBL_EPSILON);
             if (grayhi >= 1)
                grayhi = 1;
@@ -7429,6 +7575,9 @@ image_transform_png_set_background_set(PNG_CONST image_transform *this,
 
    else
    {
+      if (that->this.has_tRNS)
+         that->this.is_transparent = 1;
+
       bit_depth = that->this.bit_depth;
       expand = 1;
    }
@@ -7506,14 +7655,14 @@ image_transform_png_set_background_mod(PNG_CONST image_transform *this,
       /* Remove the alpha type and set the alpha (not in that order.) */
       that->alphaf = 1;
       that->alphae = 0;
-
-      if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
-         that->colour_type = PNG_COLOR_TYPE_RGB;
-      else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
-         that->colour_type = PNG_COLOR_TYPE_GRAY;
-      /* PNG_COLOR_TYPE_PALETTE is not changed */
    }
 
+   if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
+      that->colour_type = PNG_COLOR_TYPE_RGB;
+   else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+      that->colour_type = PNG_COLOR_TYPE_GRAY;
+   /* PNG_COLOR_TYPE_PALETTE is not changed */
+
    this->next->mod(this->next, that, pp, display);
 }
 
@@ -8301,7 +8450,8 @@ perform_transform_test(png_modifier *pm)
    png_byte bit_depth = 0;
    unsigned int palette_number = 0;
 
-   while (next_format(&colour_type, &bit_depth, &palette_number, 0))
+   while (next_format(&colour_type, &bit_depth, &palette_number, pm->test_lbg,
+            pm->test_tRNS))
    {
       png_uint_32 counter = 0;
       size_t base_pos;
@@ -8604,7 +8754,9 @@ init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
    vi->outlog = outlog(dp->pm, in_depth, out_depth);
 
    if ((dp->this.colour_type & PNG_COLOR_MASK_ALPHA) != 0 ||
-      (dp->this.colour_type == 3 && dp->this.is_transparent))
+      (dp->this.colour_type == 3 && dp->this.is_transparent) ||
+      ((dp->this.colour_type == 0 || dp->this.colour_type == 2) &&
+       dp->this.has_tRNS))
    {
       vi->do_background = dp->do_background;
 
@@ -8634,7 +8786,7 @@ init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
          vi->background_blue = b;
       }
    }
-   else
+   else /* Do not expect any background processing */
       vi->do_background = 0;
 
    if (vi->do_background == 0)
@@ -9350,6 +9502,7 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
    png_uint_32 y;
    PNG_CONST store_palette_entry *in_palette = dp->this.palette;
    PNG_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 */
    store_palette out_palette;
@@ -9365,6 +9518,7 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
 
    processing = (vi.gamma_correction > 0 && !dp->threshold_test)
       || in_bd != out_bd || in_ct != out_ct || vi.do_background;
+   process_tRNS = dp->this.has_tRNS && vi.do_background;
 
    /* TODO: FIX THIS: MAJOR BUG!  If the transformations all happen inside
     * the palette there is no way of finding out, because libpng fails to
@@ -9403,8 +9557,8 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
             /* Handle input alpha - png_set_background will cause the output
              * alpha to disappear so there is nothing to check.
              */
-            if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 || (in_ct == 3 &&
-               in_is_transparent))
+            if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 ||
+                (in_ct == 3 && in_is_transparent))
             {
                PNG_CONST unsigned int input_alpha = in_ct == 3 ?
                   dp->this.palette[in_index].alpha :
@@ -9436,6 +9590,35 @@ gamma_image_validate(gamma_display *dp, png_const_structp pp,
                }
             }
 
+            else if (process_tRNS)
+            {
+               /* alpha needs to be set appropriately for this pixel, it is
+                * currently 1 and needs to be 0 for an input pixel which matches
+                * the values in tRNS.
+                */
+               switch (in_ct)
+               {
+                  case 0: /* gray */
+                     if (sample(std, in_ct, in_bd, x, 0, 0, 0) ==
+                           dp->this.transparent.red)
+                        alpha = 0;
+                     break;
+
+                  case 2: /* RGB */
+                     if (sample(std, in_ct, in_bd, x, 0, 0, 0) ==
+                           dp->this.transparent.red &&
+                         sample(std, in_ct, in_bd, x, 1, 0, 0) ==
+                           dp->this.transparent.green &&
+                         sample(std, in_ct, in_bd, x, 2, 0, 0) ==
+                           dp->this.transparent.blue)
+                        alpha = 0;
+                     break;
+
+                  default:
+                     break;
+               }
+            }
+
             /* Handle grayscale or RGB components. */
             if ((in_ct & PNG_COLOR_MASK_COLOR) == 0) /* grayscale */
                (void)gamma_component_validate("gray", &vi,
@@ -9545,7 +9728,7 @@ gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn,
 
       modification_reset(d.pm->modifications);
 
-      /* Get a png_struct for writing the image. */
+      /* Get a png_struct for reading the image. */
       pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
       standard_palette_init(&d.this);
 
@@ -9684,9 +9867,13 @@ perform_gamma_threshold_tests(png_modifier *pm)
    /* Don't test more than one instance of each palette - it's pointless, in
     * fact this test is somewhat excessive since libpng doesn't make this
     * decision based on colour type or bit depth!
+    *
+    * CHANGED: now test two palettes and, as a side effect, images with and
+    * without tRNS.
     */
-   while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
-      if (palette_number == 0)
+   while (next_format(&colour_type, &bit_depth, &palette_number,
+                      pm->test_lbg_gamma_threshold, pm->test_tRNS))
+      if (palette_number < 2)
    {
       double test_gamma = 1.0;
       while (test_gamma >= .4)
@@ -9746,7 +9933,8 @@ static void perform_gamma_transform_tests(png_modifier *pm)
    png_byte bit_depth = 0;
    unsigned int palette_number = 0;
 
-   while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
+   while (next_format(&colour_type, &bit_depth, &palette_number,
+                      pm->test_lbg_gamma_transform, pm->test_tRNS))
    {
       unsigned int i, j;
 
@@ -9776,7 +9964,8 @@ static void perform_gamma_sbit_tests(png_modifier *pm)
       png_byte colour_type = 0, bit_depth = 0;
       unsigned int npalette = 0;
 
-      while (next_format(&colour_type, &bit_depth, &npalette, 1/*gamma*/))
+      while (next_format(&colour_type, &bit_depth, &npalette,
+                         pm->test_lbg_gamma_sbit, pm->test_tRNS))
          if ((colour_type & PNG_COLOR_MASK_ALPHA) == 0 &&
             ((colour_type == 3 && sbit < 8) ||
             (colour_type != 3 && sbit < bit_depth)))
@@ -9967,8 +10156,17 @@ static void gamma_composition_test(png_modifier *pm,
    }
 
    background.index = 193; /* rgb(193,193,193) to detect errors */
+
    if (!(colour_type & PNG_COLOR_MASK_COLOR))
    {
+      /* Because, currently, png_set_background is always called with
+       * 'need_expand' false in this case and because the gamma test itself
+       * doesn't cause an expand to 8-bit for lower bit depths the colour must
+       * be reduced to the correct range.
+       */
+      if (bit_depth < 8)
+         background.gray &= (png_uint_16)((1U << bit_depth)-1);
+
       /* Grayscale input, we do not convert to RGB (TBD), so we must set the
        * background to gray - else libpng seems to fail.
        */
@@ -10017,9 +10215,18 @@ perform_gamma_composition_tests(png_modifier *pm, int do_background,
 
    /* Skip the non-alpha cases - there is no setting of a transparency colour at
     * present.
+    *
+    * TODO: incorrect; the palette case sets tRNS and, now RGB and gray do,
+    * however the palette case fails miserably so is commented out below.
     */
-   while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
-      if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0)
+   while (next_format(&colour_type, &bit_depth, &palette_number,
+                      pm->test_lbg_gamma_composition, pm->test_tRNS))
+      if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0
+#if 0 /* TODO: FIXME */
+          /*TODO: FIXME: this should work */
+          || colour_type == 3
+#endif
+          || (colour_type != 3 && palette_number != 0))
    {
       unsigned int i, j;
 
@@ -10751,6 +10958,18 @@ int main(int argc, char **argv)
    pm.ngammas = ARRAY_SIZE(gammas);
    pm.ngamma_tests = 0; /* default to off */
 
+   /* Low bit depth gray images don't do well in the gamma tests, until
+    * this is fixed turn them off for some gamma cases:
+    */
+#  ifdef PNG_WRITE_tRNS_SUPPORTED
+      pm.test_tRNS = 1;
+#  endif
+   pm.test_lbg = 0;
+   pm.test_lbg_gamma_threshold = 1;
+   pm.test_lbg_gamma_transform = 0/*PNG_LIBPNG_VER >= 10700*/;
+   pm.test_lbg_gamma_sbit = 1;
+   pm.test_lbg_gamma_composition = 0;
+
    /* And the test encodings */
    pm.encodings = test_encodings;
    pm.nencodings = ARRAY_SIZE(test_encodings);
@@ -10863,7 +11082,7 @@ int main(int argc, char **argv)
          pm.test_gamma_transform = 1;
          pm.test_gamma_sbit = 1;
          pm.test_gamma_scale16 = 1;
-         pm.test_gamma_background = 1;
+         pm.test_gamma_background = 1; /* composition */
          pm.test_gamma_alpha_mode = 1;
          }
 
@@ -10912,6 +11131,24 @@ int main(int argc, char **argv)
       else if (strcmp(*argv, "--noexpand16") == 0)
          pm.test_gamma_expand16 = 0;
 
+      else if (strcmp(*argv, "--low-depth-gray") == 0)
+         pm.test_lbg = pm.test_lbg_gamma_threshold =
+            pm.test_lbg_gamma_transform = pm.test_lbg_gamma_sbit =
+            pm.test_lbg_gamma_composition = 1;
+
+      else if (strcmp(*argv, "--nolow-depth-gray") == 0)
+         pm.test_lbg = pm.test_lbg_gamma_threshold =
+            pm.test_lbg_gamma_transform = pm.test_lbg_gamma_sbit =
+            pm.test_lbg_gamma_composition = 0;
+
+#     ifdef PNG_WRITE_tRNS_SUPPORTED
+         else if (strcmp(*argv, "--tRNS") == 0)
+            pm.test_tRNS = 1;
+#     endif
+
+      else if (strcmp(*argv, "--notRNS") == 0)
+         pm.test_tRNS = 0;
+
       else if (strcmp(*argv, "--more-gammas") == 0)
          pm.ngamma_tests = 3U;
 
@@ -11102,7 +11339,7 @@ int main(int argc, char **argv)
    Try
    {
       /* Make useful base images */
-      make_transform_images(&pm.this);
+      make_transform_images(&pm);
 
       /* Perform the standard and gamma tests. */
       if (pm.test_standard)

libpng-manual.txt

@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.17rc04 - March 16, 2015
+ libpng version 1.6.18beta01 - April 1, 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 1.6.17rc04 - March 16, 2015
+ libpng versions 0.97, January 1998, through 1.6.18beta01 - April 1, 2015
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
 
@@ -5279,13 +5279,13 @@ Other rules can be inferred by inspecting the libpng source.
 
 XVI. Y2K Compliance in libpng
 
-March 16, 2015
+April 1, 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 1.6.17rc04 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.18beta01 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

libpng.3

@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "March 16, 2015"
+.TH LIBPNG 3 "April 1, 2015"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.17rc04
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.18beta01
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -504,7 +504,7 @@ 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 1.6.17rc04 - March 16, 2015
+ libpng version 1.6.18beta01 - April 1, 2015
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
@@ -515,7 +515,7 @@ libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.17rc04 - March 16, 2015
+ libpng versions 0.97, January 1998, through 1.6.18beta01 - April 1, 2015
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2015 Glenn Randers-Pehrson
 
@@ -5783,13 +5783,13 @@ Other rules can be inferred by inspecting the libpng source.
 
 .SH XVI. Y2K Compliance in libpng
 
-March 16, 2015
+April 1, 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 1.6.17rc04 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.18beta01 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
@@ -6042,7 +6042,9 @@ the first widely used release:
  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]
- 1.6.17rc01-04       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        16    10618  16.so.16.18[.0]
 
 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6099,7 +6101,7 @@ possible without all of you.
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.6.17rc04 - March 16, 2015:
+Libpng version 1.6.18beta01 - April 1, 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).
 
@@ -6122,8 +6124,8 @@ this sentence.
 
 This code is released under the libpng license.
 
-libpng versions 1.2.6, August 15, 2004, through 1.6.17rc04, March 16, 2015, are
-Copyright (c) 2004,2006-2014 Glenn Randers-Pehrson, and are
+libpng versions 1.2.6, August 15, 2004, through 1.6.18beta01, April 1, 2015, are
+Copyright (c) 2004,2006-2015 Glenn Randers-Pehrson, and are
 distributed according to the same disclaimer and license as libpng-1.2.5
 with the following individual added to the list of Contributing Authors
 
@@ -6221,7 +6223,7 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-March 16, 2015
+April 1, 2015
 
 .\" end of man page
 

libpngpf.3

@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "March 16, 2015"
+.TH LIBPNGPF 3 "April 1, 2015"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.17rc04
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.18beta01
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"

png.5

@@ -1,4 +1,4 @@
-.TH PNG 5 "March 16, 2015"
+.TH PNG 5 "April 1, 2015"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION

png.c

@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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_17rc04 Your_png_h_is_not_version_1_6_17rc04;
+typedef png_libpng_version_1_6_18beta01 Your_png_h_is_not_version_1_6_18beta01;
 
 /* 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
@@ -766,13 +766,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.6.17rc04 - March 16, 2015" PNG_STRING_NEWLINE \
+     "libpng version 1.6.18beta01 - April 1, 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 1.6.17rc04 - March 16, 2015\
+      return "libpng version 1.6.18beta01 - April 1, 2015\
       Copyright (c) 1998-2015 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -3034,7 +3034,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
             /* Check for an exponent, if we don't need one we are
              * done and just need to terminate the string.  At
              * this point exp_b10==(-1) is effectively if flag - it got
-             * to '-1' because of the decrement after outputing
+             * to '-1' because of the decrement after outputting
              * the decimal point above (the exponent required is
              * *not* -1!)
              */
@@ -3042,7 +3042,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
             {
                /* The following only happens if we didn't output the
                 * leading zeros above for negative exponent, so this
-                * doest add to the digit requirement.  Note that the
+                * doesn't add to the digit requirement.  Note that the
                 * two zeros here can only be output if the two leading
                 * zeros were *not* output, so this doesn't increase
                 * the output count.

png.h

@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.6.17rc04, March 16, 2015
+ * libpng version 1.6.18beta01, April 1, 2015
  *
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,7 +12,7 @@
  * Authors and maintainers:
  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *   libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.17rc04, March 16, 2015: Glenn
+ *   libpng versions 0.97, January 1998, through 1.6.18beta01, April 1, 2015: Glenn
  *   See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -214,7 +214,9 @@
  *    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]
- *    1.6.17rc01-04           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            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
@@ -246,7 +248,7 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.6.17rc04, March 16, 2015, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.6.18beta01, April 1, 2015, are
  * Copyright (c) 2004, 2006-2015 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.2.5
  * with the following individual added to the list of Contributing Authors:
@@ -358,13 +360,13 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    March 16, 2015
+ *    April 1, 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 1.6.17rc04 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.18beta01 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
@@ -426,9 +428,9 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.17rc04"
+#define PNG_LIBPNG_VER_STRING "1.6.18beta01"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.17rc04 - March 16, 2015\n"
+     " libpng version 1.6.18beta01 - April 1, 2015\n"
 
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -436,13 +438,13 @@
 /* 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 17
+#define PNG_LIBPNG_VER_RELEASE 18
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
  */
 
-#define PNG_LIBPNG_VER_BUILD  04
+#define PNG_LIBPNG_VER_BUILD  01
 
 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
@@ -459,7 +461,7 @@
 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
                                        PNG_LIBPNG_BUILD_PRIVATE */
 
-#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_RC
+#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_BETA
 
 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
  * We must not include leading zeros.
@@ -467,7 +469,7 @@
  * 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 10617 /* 1.6.17 */
+#define PNG_LIBPNG_VER 10618 /* 1.6.18 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -572,7 +574,7 @@ 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_17rc04;
+typedef char* png_libpng_version_1_6_18beta01;
 
 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
  *
@@ -1595,6 +1597,7 @@ PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
  */
 PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
     int filters));
+#endif /* WRITE */
 
 /* Flags for png_set_filter() to say which filters to use.  The flags
  * are chosen so that they don't conflict with real filter types
@@ -1620,6 +1623,7 @@ PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
 #define PNG_FILTER_VALUE_PAETH 4
 #define PNG_FILTER_VALUE_LAST  5
 
+#ifdef PNG_WRITE_SUPPORTED
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
 /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
  * defines, either the default (minimum-sum-of-absolute-differences), or

pngconf.h

@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.6.17rc04, (PENDING RELEASE)
+ * libpng version 1.6.18beta01, (PENDING RELEASE)
  *
  * Copyright (c) 1998-2015 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

pngget.c

@@ -1,7 +1,7 @@
 
 /* pngget.c - retrieval of values from info struct
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -1123,7 +1123,7 @@ png_get_unknown_chunks(png_const_structrp png_ptr, png_inforp info_ptr,
 png_byte PNGAPI
 png_get_rgb_to_gray_status (png_const_structrp png_ptr)
 {
-   return (png_byte)((png_ptr ? png_ptr->rgb_to_gray_status : 0) & 0xff);
+   return (png_byte)(png_ptr ? png_ptr->rgb_to_gray_status : 0);
 }
 #endif
 

pngpread.c

@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -168,7 +168,7 @@ png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 
    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
        num_to_check);
-   png_ptr->sig_bytes = (png_byte)((png_ptr->sig_bytes + num_to_check) & 0xff);
+   png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
 
    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
    {

pngpriv.h

@@ -1,7 +1,7 @@
 
 /* pngpriv.h - private declarations for use inside libpng
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)

pngread.c

@@ -1,7 +1,7 @@
 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -1823,6 +1823,7 @@ png_create_colormap_entry(png_image_read_control *display,
             y = (y + 128) >> 8;
             y *= 255;
             y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
+            alpha = PNG_DIV257(alpha);
             encoding = P_sRGB;
          }
 
@@ -2052,7 +2053,7 @@ make_rgb_colormap(png_image_read_control *display)
 
 /* Return a palette index to the above palette given three 8-bit sRGB values. */
 #define PNG_RGB_INDEX(r,g,b) \
-   ((png_byte)(0xff & (6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))))
+   ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
 
 static int
 png_image_read_colormap(png_voidp argument)
@@ -3025,8 +3026,7 @@ png_image_read_and_map(png_voidp argument)
                         *outrow = gray;
 
                      else
-                        *outrow =
-                            (png_byte)(0xff & (PNG_CMAP_TRANS_BACKGROUND+1));
+                        *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
                   }
                   break;
 

pngrio.c

@@ -1,7 +1,7 @@
 
 /* pngrio.c - functions for data input
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)

pngrtran.c

@@ -1,7 +1,7 @@
 
 /* pngrtran.c - transforms the data in a row for PNG readers
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -143,7 +143,7 @@ png_set_background_fixed(png_structrp png_ptr,
 
    png_ptr->background = *background_color;
    png_ptr->background_gamma = background_gamma;
-   png_ptr->background_gamma_type = (png_byte)(0xff & background_gamma_code);
+   png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
    if (need_expand != 0)
       png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
    else
@@ -1176,8 +1176,8 @@ png_init_palette_transformations(png_structrp png_ptr)
               int i, istop = png_ptr->num_trans;
 
               for (i=0; i<istop; i++)
-                 png_ptr->trans_alpha[i] = (png_byte)(0xff & (255 -
-                    png_ptr->trans_alpha[i]));
+                 png_ptr->trans_alpha[i] = (png_byte)(255 -
+                    png_ptr->trans_alpha[i]);
            }
         }
 #endif /* READ_INVERT_ALPHA */
@@ -2023,14 +2023,14 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
-      info_ptr->color_type = (png_byte)(0xff & (info_ptr->color_type |
-         PNG_COLOR_MASK_COLOR));
+      info_ptr->color_type = (png_byte)(info_ptr->color_type |
+         PNG_COLOR_MASK_COLOR);
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
-      info_ptr->color_type = (png_byte)(0xff & (info_ptr->color_type &
-         ~PNG_COLOR_MASK_COLOR));
+      info_ptr->color_type = (png_byte)(info_ptr->color_type &
+         ~PNG_COLOR_MASK_COLOR);
 #endif
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
@@ -2072,8 +2072,8 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
    if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
    {
-      info_ptr->color_type = (png_byte)(0xff & (info_ptr->color_type &
-         ~PNG_COLOR_MASK_ALPHA));
+      info_ptr->color_type = (png_byte)(info_ptr->color_type &
+         ~PNG_COLOR_MASK_ALPHA);
       info_ptr->num_trans = 0;
    }
 #endif
@@ -2106,8 +2106,8 @@ defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
    }
 #endif
 
-   info_ptr->pixel_depth = (png_byte)(0xff & (info_ptr->channels *
-       info_ptr->bit_depth));
+   info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
+       info_ptr->bit_depth);
 
    info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
 
@@ -2218,7 +2218,7 @@ png_do_unpack(png_row_infop row_info, png_bytep row)
             break;
       }
       row_info->bit_depth = 8;
-      row_info->pixel_depth = (png_byte)(0xff & (8 * row_info->channels));
+      row_info->pixel_depth = (png_byte)(8 * row_info->channels);
       row_info->rowbytes = row_width * row_info->channels;
    }
 }
@@ -2356,8 +2356,8 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
                value >>= shift[channel];
                if (++channel >= channels)
                   channel = 0;
-               *bp++ = (png_byte)(0xff & (value >> 8));
-               *bp++ = (png_byte)(0xff & value);
+               *bp++ = (png_byte)(value >> 8);
+               *bp++ = (png_byte)value;
             }
             break;
          }
@@ -2420,7 +2420,7 @@ png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
       }
 
       row_info->bit_depth = 8;
-      row_info->pixel_depth = (png_byte)(0xff & (8 * row_info->channels));
+      row_info->pixel_depth = (png_byte)(8 * row_info->channels);
       row_info->rowbytes = row_info->width * row_info->channels;
    }
 }
@@ -2448,7 +2448,7 @@ png_do_chop(png_row_infop row_info, png_bytep row)
       }
 
       row_info->bit_depth = 8;
-      row_info->pixel_depth = (png_byte)(0xff & (8 * row_info->channels));
+      row_info->pixel_depth = (png_byte)(8 * row_info->channels);
       row_info->rowbytes = row_info->width * row_info->channels;
    }
 }
@@ -2570,7 +2570,7 @@ png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 
          for (i = 0; i < row_width; i++)
          {
-            *(--dp) = (png_byte)(0xff & (255 - *(--sp)));
+            *(--dp) = (png_byte)(255 - *(--sp));
 
 /*          This does nothing:
             *(--dp) = *(--sp);
@@ -2593,8 +2593,8 @@ png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 
          for (i = 0; i < row_width; i++)
          {
-            *(--dp) = (png_byte)(0xff & (255 - *(--sp)));
-            *(--dp) = (png_byte)(0xff & (255 - *(--sp)));
+            *(--dp) = (png_byte)(255 - *(--sp));
+            *(--dp) = (png_byte)(255 - *(--sp));
 
 /*          This does nothing:
             *(--dp) = *(--sp);
@@ -2622,7 +2622,7 @@ png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 
          for (i = 0; i < row_width; i++)
          {
-            *(--dp) = (png_byte)(0xff & (255 - *(--sp)));
+            *(--dp) = (png_byte)(255 - *(--sp));
             *(--dp) = *(--sp);
          }
       }
@@ -2637,8 +2637,8 @@ png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 
          for (i = 0; i < row_width; i++)
          {
-            *(--dp) = (png_byte)(0xff & (255 - *(--sp)));
-            *(--dp) = (png_byte)(0xff & (255 - *(--sp)));
+            *(--dp) = (png_byte)(255 - *(--sp));
+            *(--dp) = (png_byte)(255 - *(--sp));
 /*
             *(--dp) = *(--sp);
             *(--dp) = *(--sp);
@@ -2662,9 +2662,9 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
    png_uint_32 row_width = row_info->width;
 
 #ifdef PNG_READ_16BIT_SUPPORTED
-   png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
+   png_byte hi_filler = (png_byte)(filler>>8);
 #endif
-   png_byte lo_filler = (png_byte)(filler & 0xff);
+   png_byte lo_filler = (png_byte)filler;
 
    png_debug(1, "in png_do_read_filler");
 
@@ -2918,10 +2918,10 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
             }
          }
       }
-      row_info->channels = (png_byte)(0xff & (row_info->channels + 2));
+      row_info->channels = (png_byte)(row_info->channels + 2);
       row_info->color_type |= PNG_COLOR_MASK_COLOR;
-      row_info->pixel_depth = (png_byte)(0xff & (row_info->channels *
-          row_info->bit_depth));
+      row_info->pixel_depth = (png_byte)(row_info->channels *
+          row_info->bit_depth);
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
    }
 }
@@ -3063,8 +3063,7 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
                   /* NOTE: this is the historical approach which simply
                    * truncates the results.
                    */
-                  *(dp++) =
-                      (png_byte)(0xff & ((rc*red + gc*green + bc*blue)>>15));
+                  *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
                }
 
                else
@@ -3106,16 +3105,16 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
 
                else
                {
-                  png_uint_16 red_1   = png_ptr->gamma_16_to_1[(red&0xff)
+                  png_uint_16 red_1   = png_ptr->gamma_16_to_1[(red & 0xff)
                       >> png_ptr->gamma_shift][red>>8];
                   png_uint_16 green_1 =
-                      png_ptr->gamma_16_to_1[(green&0xff) >>
+                      png_ptr->gamma_16_to_1[(green & 0xff) >>
                       png_ptr->gamma_shift][green>>8];
-                  png_uint_16 blue_1  = png_ptr->gamma_16_to_1[(blue&0xff)
+                  png_uint_16 blue_1  = png_ptr->gamma_16_to_1[(blue & 0xff)
                       >> png_ptr->gamma_shift][blue>>8];
                   png_uint_16 gray16  = (png_uint_16)((rc*red_1 + gc*green_1
                       + bc*blue_1 + 16384)>>15);
-                  w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
+                  w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >>
                       png_ptr->gamma_shift][gray16 >> 8];
                   rgb_error |= 1;
                }
@@ -3167,11 +3166,11 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
          }
       }
 
-      row_info->channels = (png_byte)(0xff & (row_info->channels - 2));
-      row_info->color_type = (png_byte)(0xff & (row_info->color_type &
-          ~PNG_COLOR_MASK_COLOR));
-      row_info->pixel_depth = (png_byte)(0xff & (row_info->channels *
-          row_info->bit_depth));
+      row_info->channels = (png_byte)(row_info->channels - 2);
+      row_info->color_type = (png_byte)(row_info->color_type &
+          ~PNG_COLOR_MASK_COLOR);
+      row_info->pixel_depth = (png_byte)(row_info->channels *
+          row_info->bit_depth);
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
    }
    return rgb_error;
@@ -3413,10 +3412,10 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         if (v == png_ptr->trans_color.gray)
                         {
                            /* Background is already in screen gamma */
-                           *sp = (png_byte)(0xff &
-                                (png_ptr->background.gray >> 8));
-                           *(sp + 1) = (png_byte)(0xff &
-                                png_ptr->background.gray);
+                           *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
+                           *(sp + 1) = (png_byte)(png_ptr->background.gray
+                                & 0xff);
                         }
 
                         else
@@ -3439,10 +3438,10 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 
                         if (v == png_ptr->trans_color.gray)
                         {
-                           *sp = (png_byte)(0xff &
-                               (png_ptr->background.gray >> 8));
-                           *(sp + 1) = (png_byte)(0xff &
-                                png_ptr->background.gray);
+                           *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
+                           *(sp + 1) = (png_byte)(png_ptr->background.gray
+                                & 0xff);
                         }
                      }
                   }
@@ -3520,18 +3519,15 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                          b == png_ptr->trans_color.blue)
                      {
                         /* Background is already in screen gamma */
-                        *sp = (png_byte)(0xff &
-                            (png_ptr->background.red >> 8));
-                        *(sp + 1) = (png_byte)(0xff &
-                            png_ptr->background.red);
-                        *(sp + 2) = (png_byte)(0xff &
-                            (png_ptr->background.green >> 8));
-                        *(sp + 3) = (png_byte)(0xff &
-                            png_ptr->background.green);
-                        *(sp + 4) = (png_byte)(0xff &
-                            (png_ptr->background.blue >> 8));
-                        *(sp + 5) = (png_byte)(0xff &
-                            png_ptr->background.blue);
+                        *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+                        *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
+                        *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
 
                      else
@@ -3569,15 +3565,15 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                          g == png_ptr->trans_color.green &&
                          b == png_ptr->trans_color.blue)
                      {
-                        *sp = (png_byte)(0xff & (png_ptr->background.red >> 8));
-                        *(sp + 1) = (png_byte)(0xff & png_ptr->background.red);
-                        *(sp + 2) = (png_byte)(0xff &
-                            (png_ptr->background.green >> 8));
-                        *(sp + 3) = (png_byte)(0xff &
-                             png_ptr->background.green);
-                        *(sp + 4) = (png_byte)(0xff &
-                             (png_ptr->background.blue >> 8));
-                        *(sp + 5) = (png_byte)(0xff & png_ptr->background.blue);
+                        *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+                        *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
+                        *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
                   }
                }
@@ -3659,9 +3655,9 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                      else if (a == 0)
                      {
                         /* Background is already in screen gamma */
-                        *sp = (png_byte)(0xff &
-                            (png_ptr->background.gray >> 8));
-                        *(sp + 1) = (png_byte)(0xff & png_ptr->background.gray);
+                        *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
+                        *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
                      }
 
                      else
@@ -3673,7 +3669,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         if (optimize != 0)
                            w = v;
                         else
-                           w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
+                           w = gamma_16_from_1[(v & 0xff) >>
+                               gamma_shift][v >> 8];
                         *sp = (png_byte)((w >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(w & 0xff);
                      }
@@ -3690,9 +3687,9 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 
                      if (a == 0)
                      {
-                        *sp = (png_byte)(0xff &
-                            (png_ptr->background.gray >> 8));
-                        *(sp + 1) = (png_byte)(0xff & png_ptr->background.gray);
+                        *sp = (png_byte)((png_ptr->background.gray >> 8)
+                                & 0xff);
+                        *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
                      }
 
                      else if (a < 0xffff)
@@ -3819,15 +3816,15 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                      else if (a == 0)
                      {
                         /* Background is already in screen gamma */
-                        *sp = (png_byte)(0xff & (png_ptr->background.red >> 8));
-                        *(sp + 1) = (png_byte)(0xff & png_ptr->background.red );
-                        *(sp + 2) = (png_byte)(0xff &
-                             (png_ptr->background.green >> 8));
-                        *(sp + 3) = (png_byte)(0xff &
-                                png_ptr->background.green);
-                        *(sp + 4) = (png_byte)(0xff &
-                               (png_ptr->background.blue >> 8));
-                        *(sp + 5) = (png_byte)(0xff & png_ptr->background.blue);
+                        *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+                        *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
+                        *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
 
                      else
@@ -3837,15 +3834,15 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
                         png_composite_16(w, v, a, png_ptr->background_1.red);
                         if (optimize == 0)
-                           w = gamma_16_from_1[((w & 0xff) >>
-                                gamma_shift)][w >> 8];
+                           w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
+                                8];
                         *sp = (png_byte)((w >> 8) & 0xff);
                         *(sp + 1) = (png_byte)(w & 0xff);
 
                         v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
                         png_composite_16(w, v, a, png_ptr->background_1.green);
                         if (optimize == 0)
-                           w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
+                           w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
                                 8];
 
                         *(sp + 2) = (png_byte)((w >> 8) & 0xff);
@@ -3854,7 +3851,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
                         png_composite_16(w, v, a, png_ptr->background_1.blue);
                         if (optimize == 0)
-                           w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
+                           w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >>
                                 8];
 
                         *(sp + 4) = (png_byte)((w >> 8) & 0xff);
@@ -3874,16 +3871,15 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 
                      if (a == 0)
                      {
-                        *sp = (png_byte)(0xff & (png_ptr->background.red >> 8));
-                        *(sp + 1) = (png_byte)(0xff & png_ptr->background.red);
-                        *(sp + 2) = (png_byte)(0xff &
-                               (png_ptr->background.green >> 8));
-                        *(sp + 3) = (png_byte)(0xff &
-                                png_ptr->background.green);
-                        *(sp + 4) = (png_byte)(0xff &
-                                (png_ptr->background.blue >> 8));
-                        *(sp + 5) = (png_byte)(0xff &
-                                png_ptr->background.blue & 0xff);
+                        *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
+                        *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
+                        *(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
+                                & 0xff);
+                        *(sp + 3) = (png_byte)(png_ptr->background.green
+                                & 0xff);
+                        *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
+                                & 0xff);
+                        *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
                      }
 
                      else if (a < 0xffff)
@@ -4070,12 +4066,11 @@ png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                   int c = *sp & 0x0c;
                   int d = *sp & 0x03;
 
-                  *sp = (png_byte)(0xff &
-                      (((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)])  ) & 0xc0)|
+                  *sp = (png_byte)(
+                      ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)])   ) & 0xc0)|
                       ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
                       ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
-                      ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) & 0xff))
-                      );
+                      ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
                   sp++;
                }
             }
@@ -4406,8 +4401,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
                   for (i = 0; i < row_width; i++)
                   {
                      value = (*sp >> shift) & 0x03;
-                     *dp = (png_byte)(0xff & (value | (value << 2) |
-                        (value << 4) | (value << 6)));
+                     *dp = (png_byte)(value | (value << 2) | (value << 4) |
+                        (value << 6));
                      if (shift == 6)
                      {
                         shift = 0;
@@ -4431,7 +4426,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
                   for (i = 0; i < row_width; i++)
                   {
                      value = (*sp >> shift) & 0x0f;
-                     *dp = (png_byte)(0xff & (value | (value << 4)));
+                     *dp = (png_byte)(value | (value << 4));
                      if (shift == 4)
                      {
                         shift = 0;
@@ -4502,8 +4497,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
 
             row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
             row_info->channels = 2;
-            row_info->pixel_depth =
-               (png_byte)(0xff & (row_info->bit_depth << 1));
+            row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
             row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
                row_width);
          }
@@ -4570,7 +4564,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
          }
          row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
          row_info->channels = 4;
-         row_info->pixel_depth = (png_byte)(0xff & (row_info->bit_depth << 2));
+         row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
          row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
       }
    }
@@ -4603,7 +4597,7 @@ png_do_expand_16(png_row_infop row_info, png_bytep row)
 
       row_info->rowbytes *= 2;
       row_info->bit_depth = 16;
-      row_info->pixel_depth = (png_byte)(0xff & (row_info->channels * 16));
+      row_info->pixel_depth = (png_byte)(row_info->channels * 16);
    }
 }
 #endif
@@ -4991,8 +4985,8 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
       if (png_ptr->user_transform_channels != 0)
          row_info->channels = png_ptr->user_transform_channels;
 #endif
-      row_info->pixel_depth = (png_byte)(0xff & (row_info->bit_depth *
-          row_info->channels));
+      row_info->pixel_depth = (png_byte)(row_info->bit_depth *
+          row_info->channels);
 
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
    }

pngrutil.c

@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.18 [(PENDING RELEASE)]
  * 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.)
@@ -575,7 +575,7 @@ png_decompress_chunk(png_structrp png_ptr,
     */
    png_alloc_size_t limit = PNG_SIZE_MAX;
 
-# ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
    if (png_ptr->user_chunk_malloc_max > 0 &&
        png_ptr->user_chunk_malloc_max < limit)
       limit = png_ptr->user_chunk_malloc_max;
@@ -822,13 +822,13 @@ png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    /* Set internal variables */
    png_ptr->width = width;
    png_ptr->height = height;
-   png_ptr->bit_depth = (png_byte)(bit_depth & 0xff);
-   png_ptr->interlaced = (png_byte)(interlace_type & 0xff);
-   png_ptr->color_type = (png_byte)(color_type & 0xff);
+   png_ptr->bit_depth = (png_byte)bit_depth;
+   png_ptr->interlaced = (png_byte)interlace_type;
+   png_ptr->color_type = (png_byte)color_type;
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   png_ptr->filter_type = (png_byte)(filter_type & 0xff);
+   png_ptr->filter_type = (png_byte)filter_type;
 #endif
-   png_ptr->compression_type = (png_byte)(compression_type & 0xff);
+   png_ptr->compression_type = (png_byte)compression_type;
 
    /* Find number of channels */
    switch (png_ptr->color_type)
@@ -853,8 +853,7 @@ png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    }
 
    /* Set up other useful info */
-   png_ptr->pixel_depth =
-       (png_byte)(0xff & (png_ptr->bit_depth * png_ptr->channels));
+   png_ptr->pixel_depth = (png_byte)(png_ptr->bit_depth * png_ptr->channels);
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->width);
    png_debug1(3, "bit_depth = %d", png_ptr->bit_depth);
    png_debug1(3, "channels = %d", png_ptr->channels);
@@ -2716,7 +2715,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
       png_ptr->unknown_chunk.data = NULL;
    }
 
-#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
       if (png_ptr->user_chunk_malloc_max > 0 &&
           png_ptr->user_chunk_malloc_max < limit)
          limit = png_ptr->user_chunk_malloc_max;
@@ -2732,8 +2731,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
       /* The following is safe because of the PNG_SIZE_MAX init above */
       png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
       /* 'mode' is a flag array, only the bottom four bits matter here */
-      png_ptr->unknown_chunk.location =
-          (png_byte)(0xff & png_ptr->mode/*SAFE*/);
+      png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
 
       if (length == 0)
          png_ptr->unknown_chunk.data = NULL;
@@ -3230,7 +3228,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
             if (m != 0) /* something to copy */
             {
                if (m != 0xff)
-                  *dp = (png_byte)(((*dp & ~m) | (*sp & m)) & 0xff);
+                  *dp = (png_byte)((*dp & ~m) | (*sp & m));
                else
                   *dp = *sp;
             }
@@ -3482,8 +3480,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
 
    /* Restore the overwritten bits from the last byte if necessary. */
    if (end_ptr != NULL)
-      *end_ptr =
-          (png_byte)(0xff & ((end_byte & end_mask) | (*end_ptr & ~end_mask)));
+      *end_ptr = (png_byte)((end_byte & end_mask) | (*end_ptr & ~end_mask));
 }
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
@@ -3777,14 +3774,16 @@ png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
 
    for (i = 0; i < bpp; i++)
    {
-      *rp = (png_byte)(((int)(*rp) + ((int)(*pp++) / 2 )) & 0xff);
+      *rp = (png_byte)(((int)(*rp) +
+         ((int)(*pp++) / 2 )) & 0xff);
 
       rp++;
    }
 
    for (i = 0; i < istop; i++)
    {
-      *rp = (png_byte)(((int)(*rp) + (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+      *rp = (png_byte)(((int)(*rp) +
+         (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
 
       rp++;
    }
@@ -3800,7 +3799,7 @@ png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
    /* First pixel/byte */
    c = *prev_row++;
    a = *row + c;
-   *row++ = (png_byte)(a & 0xff);
+   *row++ = (png_byte)a;
 
    /* Remainder */
    while (row < rp_end)
@@ -3834,7 +3833,7 @@ png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
        */
       c = b;
       a += *row;
-      *row++ = (png_byte)(a & 0xff);
+      *row++ = (png_byte)a;
    }
 }
 
@@ -3851,7 +3850,7 @@ png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
    while (row < rp_end)
    {
       int a = *row + *prev_row++;
-      *row++ = (png_byte)(a & 0xff);
+      *row++ = (png_byte)a;
    }
 
    /* Remainder */
@@ -3882,7 +3881,7 @@ png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
       if (pc < pa) a = c;
 
       a += *row;
-      *row++ = (png_byte)(a & 0xff);
+      *row++ = (png_byte)a;
    }
 }
 
@@ -4375,7 +4374,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    /* This value is stored in png_struct and double checked in the row read
     * code.
     */
-   png_ptr->maximum_pixel_depth = (png_byte)(max_pixel_depth & 0xff);
+   png_ptr->maximum_pixel_depth = (png_byte)max_pixel_depth;
    png_ptr->transformed_pixel_depth = 0; /* calculated on demand */
 
    /* Align the width on the next larger 8 pixels.  Mainly used
@@ -4447,11 +4446,8 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    png_debug1(3, "height = %u,", png_ptr->height);
    png_debug1(3, "iwidth = %u,", png_ptr->iwidth);
    png_debug1(3, "num_rows = %u,", png_ptr->num_rows);
-   png_debug1(3, "row_bytes = %lu,", (unsigned long)row_bytes);
-   png_debug1(3, "png_ptr->rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
-   png_debug1(3, "png_ptr->info_rowbytes = %lu,",
-       (unsigned long)png_ptr->info_rowbytes);
-   png_debug1(3, "PNG_ROWBYTES = %lu",
+   png_debug1(3, "rowbytes = %lu,", (unsigned long)png_ptr->rowbytes);
+   png_debug1(3, "irowbytes = %lu",
        (unsigned long)PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
 
    /* The sequential reader needs a buffer for IDAT, but the progressive reader

pngset.c

@@ -1,7 +1,7 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)

pngtest.c

@@ -1,7 +1,7 @@
 
 /* pngtest.c - a simple test program to test libpng
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -2028,4 +2028,4 @@ main(void)
 #endif
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_17rc04 Your_png_h_is_not_version_1_6_17rc04;
+typedef png_libpng_version_1_6_18beta01 Your_png_h_is_not_version_1_6_18beta01;

pngtrans.c

@@ -1,7 +1,7 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -273,7 +273,7 @@ png_do_invert(png_row_infop row_info, png_bytep row)
 
       for (i = 0; i < istop; i++)
       {
-         *rp = (png_byte)((~(*rp)) & 0xff);
+         *rp = (png_byte)(~(*rp));
          rp++;
       }
    }
@@ -287,7 +287,7 @@ png_do_invert(png_row_infop row_info, png_bytep row)
 
       for (i = 0; i < istop; i += 2)
       {
-         *rp = (png_byte)((~(*rp)) & 0xff);
+         *rp = (png_byte)(~(*rp));
          rp += 2;
       }
    }
@@ -302,8 +302,8 @@ png_do_invert(png_row_infop row_info, png_bytep row)
 
       for (i = 0; i < istop; i += 4)
       {
-         *rp = (png_byte)((~(*rp)) & 0xff);
-         *(rp + 1) = (png_byte)((~(*(rp + 1))) & 0xff);
+         *rp = (png_byte)(~(*rp));
+         *(rp + 1) = (png_byte)(~(*(rp + 1)));
          rp += 4;
       }
    }
@@ -803,9 +803,8 @@ png_set_user_transform_info(png_structrp png_ptr, png_voidp
 #endif
 
    png_ptr->user_transform_ptr = user_transform_ptr;
-   png_ptr->user_transform_depth = (png_byte)(user_transform_depth & 0xff);
-   png_ptr->user_transform_channels =
-       (png_byte)(user_transform_channels & 0xff);
+   png_ptr->user_transform_depth = (png_byte)user_transform_depth;
+   png_ptr->user_transform_channels = (png_byte)user_transform_channels;
 }
 #endif
 

pngwrite.c

@@ -1,7 +1,7 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -219,7 +219,7 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
          int j;
          for (j = 0; j<(int)info_ptr->num_trans; j++)
             info_ptr->trans_alpha[j] =
-               (png_byte)((255 - info_ptr->trans_alpha[j]) & 0xff);
+               (png_byte)(255 - info_ptr->trans_alpha[j]);
       }
 #endif
       png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
@@ -457,11 +457,11 @@ png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
    png_debug(1, "in png_convert_from_struct_tm");
 
    ptime->year = (png_uint_16)(1900 + ttime->tm_year);
-   ptime->month = (png_byte)((ttime->tm_mon + 1) & 0xff);
-   ptime->day = (png_byte)(ttime->tm_mday & 0xff);
-   ptime->hour = (png_byte)(ttime->tm_hour & 0xff);
-   ptime->minute = (png_byte)(ttime->tm_min & 0xff);
-   ptime->second = (png_byte)(ttime->tm_sec & 0xff);
+   ptime->month = (png_byte)(ttime->tm_mon + 1);
+   ptime->day = (png_byte)ttime->tm_mday;
+   ptime->hour = (png_byte)ttime->tm_hour;
+   ptime->minute = (png_byte)ttime->tm_min;
+   ptime->second = (png_byte)ttime->tm_sec;
 }
 
 void PNGAPI
@@ -638,8 +638,8 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 
          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
          {
-            *(rp)     = (png_byte)((*rp       - *(rp + 1)) & 0xff);
-            *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
+            *(rp)     = (png_byte)(*rp       - *(rp + 1));
+            *(rp + 2) = (png_byte)(*(rp + 2) - *(rp + 1));
          }
       }
 
@@ -665,10 +665,10 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
             png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
             png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
             png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
-            *(rp    ) = (png_byte)((red >> 8) & 0xff);
-            *(rp + 1) = (png_byte)(red & 0xff);
-            *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
-            *(rp + 5) = (png_byte)(blue & 0xff);
+            *(rp    ) = (png_byte)(red >> 8);
+            *(rp + 1) = (png_byte)red;
+            *(rp + 4) = (png_byte)(blue >> 8);
+            *(rp + 5) = (png_byte)blue;
          }
       }
 #endif /* WRITE_16BIT */
@@ -811,8 +811,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
    row_info.width = png_ptr->usr_width;
    row_info.channels = png_ptr->usr_channels;
    row_info.bit_depth = png_ptr->usr_bit_depth;
-   row_info.pixel_depth =
-       (png_byte)(0xff & (row_info.bit_depth * row_info.channels));
+   row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
    row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
 
    png_debug1(3, "row_info->color_type = %d", row_info.color_type);
@@ -1038,7 +1037,7 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
             png_ptr->do_filter = PNG_FILTER_PAETH; break;
 
          default:
-            png_ptr->do_filter = (png_byte)(filters & 0xff); break;
+            png_ptr->do_filter = (png_byte)filters; break;
 #else
          default:
             png_app_error(png_ptr, "Unknown row filter for method 0");
@@ -1071,8 +1070,8 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
             if (png_ptr->prev_row == NULL)
             {
                png_warning(png_ptr, "Can't add Up filter after starting");
-               png_ptr->do_filter =
-                  (png_byte)((png_ptr->do_filter & ~PNG_FILTER_UP) & 0xff);
+               png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
+                   ~PNG_FILTER_UP);
             }
 
             else
@@ -1089,8 +1088,8 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
             if (png_ptr->prev_row == NULL)
             {
                png_warning(png_ptr, "Can't add Average filter after starting");
-               png_ptr->do_filter =
-                   (png_byte)((png_ptr->do_filter & ~PNG_FILTER_AVG) & 0xff);
+               png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
+                   ~PNG_FILTER_AVG);
             }
 
             else
@@ -1107,7 +1106,7 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
             if (png_ptr->prev_row == NULL)
             {
                png_warning(png_ptr, "Can't add Paeth filter after starting");
-               png_ptr->do_filter &= (png_byte)((~PNG_FILTER_PAETH) & 0xff);
+               png_ptr->do_filter &= (png_byte)(~PNG_FILTER_PAETH);
             }
 
             else
@@ -1211,7 +1210,7 @@ png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
          }
 
          /* Safe to set this now */
-         png_ptr->num_prev_filters = (png_byte)(num_weights & 0xff);
+         png_ptr->num_prev_filters = (png_byte)num_weights;
       }
 
       /* If, in the future, there are other filter methods, this would
@@ -1891,7 +1890,7 @@ png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
          component *= 255;
 
       /* Convert the component to sRGB. */
-      return (png_byte)(PNG_sRGB_FROM_LINEAR(component) & 0xff);
+      return (png_byte)PNG_sRGB_FROM_LINEAR(component);
    }
 
    else
@@ -1940,7 +1939,7 @@ png_write_image_8bit(png_voidp argument)
          while (out_ptr < row_end)
          {
             png_uint_16 alpha = in_ptr[aindex];
-            png_byte alphabyte = (png_byte)(PNG_DIV257(alpha) & 0xff);
+            png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
             png_uint_32 reciprocal = 0;
             int c;
 
@@ -1983,7 +1982,7 @@ png_write_image_8bit(png_voidp argument)
             png_uint_32 component = *in_ptr++;
 
             component *= 255;
-            *out_ptr++ = (png_byte)(PNG_sRGB_FROM_LINEAR(component) & 0xff);
+            *out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
          }
 
          png_write_row(png_ptr, output_row);
@@ -2042,23 +2041,23 @@ png_image_set_PLTE(png_image_write_control *display)
          {
             if (channels >= 3) /* RGB */
             {
-               palette[i].blue = (png_byte)(0xff & PNG_sRGB_FROM_LINEAR(255 *
-                  entry[(2 ^ bgr)]));
-               palette[i].green = (png_byte)(0xff & PNG_sRGB_FROM_LINEAR(255 *
-                  entry[1]));
-               palette[i].red = (png_byte)(0xff & PNG_sRGB_FROM_LINEAR(255 *
-                  entry[bgr]));
+               palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
+                  entry[(2 ^ bgr)]);
+               palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
+                  entry[1]);
+               palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
+                  entry[bgr]);
             }
 
             else /* Gray */
                palette[i].blue = palette[i].red = palette[i].green =
-                  (png_byte)(PNG_sRGB_FROM_LINEAR((255 * *entry)) & 0xff);
+                  (png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
          }
 
          else /* alpha */
          {
             png_uint_16 alpha = entry[afirst ? 0 : channels-1];
-            png_byte alphabyte = (png_byte)(PNG_DIV257(alpha) & 0xff);
+            png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
             png_uint_32 reciprocal = 0;
 
             /* Calculate a reciprocal, as in the png_write_image_8bit code above

pngwtran.c

@@ -1,7 +1,7 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -56,14 +56,14 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
                else
                {
                   mask = 0x80;
-                  *dp = (png_byte)(v & 0xff);
+                  *dp = (png_byte)v;
                   dp++;
                   v = 0;
                }
             }
 
             if (mask != 0x80)
-               *dp = (png_byte)(v & 0xff);
+               *dp = (png_byte)v;
 
             break;
          }
@@ -90,7 +90,7 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
                if (shift == 0)
                {
                   shift = 6;
-                  *dp = (png_byte)(v & 0xff);
+                  *dp = (png_byte)v;
                   dp++;
                   v = 0;
                }
@@ -102,7 +102,7 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
             }
 
             if (shift != 6)
-               *dp = (png_byte)(v & 0xff);
+               *dp = (png_byte)v;
 
             break;
          }
@@ -129,7 +129,7 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
                if (shift == 0)
                {
                   shift = 4;
-                  *dp = (png_byte)(v & 0xff);
+                  *dp = (png_byte)v;
                   dp++;
                   v = 0;
                }
@@ -141,7 +141,7 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
             }
 
             if (shift != 4)
-               *dp = (png_byte)(v & 0xff);
+               *dp = (png_byte)v;
 
             break;
          }
@@ -150,9 +150,8 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
             break;
       }
 
-      row_info->bit_depth = (png_byte)(bit_depth & 0xff);
-      row_info->pixel_depth =
-          (png_byte)((bit_depth * row_info->channels) & 0xff);
+      row_info->bit_depth = (png_byte)bit_depth;
+      row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
           row_info->width);
    }
@@ -423,7 +422,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = *(sp++);
                */
                sp+=3; dp = sp;
-               *(dp++) = (png_byte)((255 - *(sp++)) & 0xff);
+               *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
 
@@ -446,8 +445,8 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = *(sp++);
                */
                sp+=6; dp = sp;
-               *(dp++) = (png_byte)((255 - *(sp++)) & 0xff);
-               *(dp++) = (png_byte)((255 - *(sp++)) & 0xff);
+               *(dp++) = (png_byte)(255 - *(sp++));
+               *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
 #endif /* WRITE_16BIT */
@@ -465,7 +464,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
             for (i = 0, sp = dp = row; i < row_width; i++)
             {
                *(dp++) = *(sp++);
-               *(dp++) = (png_byte)((255 - *(sp++)) & 0xff);
+               *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
 
@@ -484,8 +483,8 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = *(sp++);
                */
                sp+=2; dp = sp;
-               *(dp++) = (png_byte)((255 - *(sp++)) & 0xff);
-               *(dp++) = (png_byte)((255 - *(sp++)) & 0xff);
+               *(dp++) = (png_byte)(255 - *(sp++));
+               *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
 #endif /* WRITE_16BIT */

pngwutil.c

@@ -1,7 +1,7 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 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.)
@@ -23,10 +23,10 @@
 void PNGAPI
 png_save_uint_32(png_bytep buf, png_uint_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);
+   buf[0] = (png_byte)(i >> 24);
+   buf[1] = (png_byte)(i >> 16);
+   buf[2] = (png_byte)(i >> 8);
+   buf[3] = (png_byte)(i     );
 }
 
 /* Place a 16-bit number into a buffer in PNG byte order.
@@ -36,8 +36,8 @@ png_save_uint_32(png_bytep buf, png_uint_32 i)
 void PNGAPI
 png_save_uint_16(png_bytep buf, unsigned int i)
 {
-   buf[0] = (png_byte)((i >> 8) & 0xff);
-   buf[1] = (png_byte)(i & 0xff);
+   buf[0] = (png_byte)(i >> 8);
+   buf[1] = (png_byte)(i     );
 }
 #endif
 
@@ -278,10 +278,10 @@ optimize_cmf(png_bytep data, png_alloc_size_t data_size)
 
             z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
 
-            data[0] = (png_byte)(z_cmf & 0xff);
+            data[0] = (png_byte)z_cmf;
             tmp = data[1] & 0xe0;
             tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f;
-            data[1] = (png_byte)(tmp & 0xff);
+            data[1] = (png_byte)tmp;
          }
       }
    }
@@ -695,7 +695,7 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
 
    while (*key && key_len < 79)
    {
-      png_byte ch = (png_byte)(0xff & *key++);
+      png_byte ch = (png_byte)*key++;
 
       if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
          *new_key++ = ch, ++key_len, space = 0;
@@ -872,17 +872,17 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
 #endif
 
    /* Save the relevant information */
-   png_ptr->bit_depth = (png_byte)(bit_depth & 0xff);
-   png_ptr->color_type = (png_byte)(color_type & 0xff);
-   png_ptr->interlaced = (png_byte)(interlace_type & 0xff);
+   png_ptr->bit_depth = (png_byte)bit_depth;
+   png_ptr->color_type = (png_byte)color_type;
+   png_ptr->interlaced = (png_byte)interlace_type;
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   png_ptr->filter_type = (png_byte)(filter_type & 0xff);
+   png_ptr->filter_type = (png_byte)filter_type;
 #endif
-   png_ptr->compression_type = (png_byte)(compression_type & 0xff);
+   png_ptr->compression_type = (png_byte)compression_type;
    png_ptr->width = width;
    png_ptr->height = height;
 
-   png_ptr->pixel_depth = (png_byte)((bit_depth * png_ptr->channels) & 0xff);
+   png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
    /* Set the usr info, so any transformations can modify it */
    png_ptr->usr_width = png_ptr->width;
@@ -892,11 +892,11 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
    /* Pack the header information into the buffer */
    png_save_uint_32(buf, width);
    png_save_uint_32(buf + 4, height);
-   buf[8] = (png_byte)(bit_depth & 0xff);
-   buf[9] = (png_byte)(color_type & 0xff);
-   buf[10] = (png_byte)(compression_type & 0xff);
-   buf[11] = (png_byte)(filter_type & 0xff);
-   buf[12] = (png_byte)(interlace_type & 0xff);
+   buf[8] = (png_byte)bit_depth;
+   buf[9] = (png_byte)color_type;
+   buf[10] = (png_byte)compression_type;
+   buf[11] = (png_byte)filter_type;
+   buf[12] = (png_byte)interlace_type;
 
    /* Write the chunk */
    png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
@@ -1181,7 +1181,7 @@ png_write_sRGB(png_structrp png_ptr, int srgb_intent)
       png_warning(png_ptr,
           "Invalid sRGB rendering intent specified");
 
-   buf[0]=(png_byte)(srgb_intent & 0xff);
+   buf[0]=(png_byte)srgb_intent;
    png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
 }
 #endif
@@ -1285,10 +1285,10 @@ png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
    {
       if (spalette->depth == 8)
       {
-         entrybuf[0] = (png_byte)(ep->red & 0xff);
-         entrybuf[1] = (png_byte)(ep->green & 0xff);
-         entrybuf[2] = (png_byte)(ep->blue & 0xff);
-         entrybuf[3] = (png_byte)(ep->alpha & 0xff);
+         entrybuf[0] = (png_byte)ep->red;
+         entrybuf[1] = (png_byte)ep->green;
+         entrybuf[2] = (png_byte)ep->blue;
+         entrybuf[3] = (png_byte)ep->alpha;
          png_save_uint_16(entrybuf + 4, ep->frequency);
       }
 
@@ -1309,10 +1309,10 @@ png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
    {
       if (spalette->depth == 8)
       {
-         entrybuf[0] = (png_byte)(ep[i].red & 0xff);
-         entrybuf[1] = (png_byte)(ep[i].green & 0xff);
-         entrybuf[2] = (png_byte)(ep[i].blue & 0xff);
-         entrybuf[3] = (png_byte)(ep[i].alpha & 0xff);
+         entrybuf[0] = (png_byte)ep[i].red;
+         entrybuf[1] = (png_byte)ep[i].green;
+         entrybuf[2] = (png_byte)ep[i].blue;
+         entrybuf[3] = (png_byte)ep[i].alpha;
          png_save_uint_16(entrybuf + 4, ep[i].frequency);
       }
 
@@ -1348,8 +1348,8 @@ png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
    {
       png_byte maxbits;
 
-      maxbits = (png_byte)((color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
-          png_ptr->usr_bit_depth) & 0xff);
+      maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
+          png_ptr->usr_bit_depth);
 
       if (sbit->red == 0 || sbit->red > maxbits ||
           sbit->green == 0 || sbit->green > maxbits ||
@@ -1786,7 +1786,7 @@ png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
 
    png_save_int_32(buf, x_offset);
    png_save_int_32(buf + 4, y_offset);
-   buf[8] = (png_byte)(unit_type & 0xff);
+   buf[8] = (png_byte)unit_type;
 
    png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
 }
@@ -1841,8 +1841,8 @@ png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
    png_write_chunk_data(png_ptr, new_purpose, purpose_len);
    png_save_int_32(buf, X0);
    png_save_int_32(buf + 4, X1);
-   buf[8] = (png_byte)(type & 0xff);
-   buf[9] = (png_byte)(nparams & 0xff);
+   buf[8] = (png_byte)type;
+   buf[9] = (png_byte)nparams;
    png_write_chunk_data(png_ptr, buf, (png_size_t)10);
    png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
 
@@ -1877,7 +1877,7 @@ png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
       return;
    }
 
-   buf[0] = (png_byte)(unit & 0xff);
+   buf[0] = (png_byte)unit;
    memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
    memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
 
@@ -1902,7 +1902,7 @@ png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
 
    png_save_uint_32(buf, x_pixels_per_unit);
    png_save_uint_32(buf + 4, y_pixels_per_unit);
-   buf[8] = (png_byte)(unit_type & 0xff);
+   buf[8] = (png_byte)unit_type;
 
    png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
 }
@@ -1968,7 +1968,7 @@ png_write_start_row(png_structrp png_ptr)
 
    /* 1.5.6: added to allow checking in the row write code. */
    png_ptr->transformed_pixel_depth = png_ptr->pixel_depth;
-   png_ptr->maximum_pixel_depth = (png_byte)(usr_pixel_depth & 0xff);
+   png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth;
 
    /* Set up row buffer */
    png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, buf_size);
@@ -2180,7 +2180,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
                if (shift == 0)
                {
                   shift = 7;
-                  *dp++ = (png_byte)(d & 0xff);
+                  *dp++ = (png_byte)d;
                   d = 0;
                }
 
@@ -2189,7 +2189,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 
             }
             if (shift != 7)
-               *dp = (png_byte)(d & 0xff);
+               *dp = (png_byte)d;
 
             break;
          }
@@ -2218,7 +2218,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
                if (shift == 0)
                {
                   shift = 6;
-                  *dp++ = (png_byte)(d & 0xff);
+                  *dp++ = (png_byte)d;
                   d = 0;
                }
 
@@ -2226,7 +2226,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
                   shift -= 2;
             }
             if (shift != 6)
-               *dp = (png_byte)(d & 0xff);
+               *dp = (png_byte)d;
 
             break;
          }
@@ -2254,7 +2254,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
                if (shift == 0)
                {
                   shift = 4;
-                  *dp++ = (png_byte)(d & 0xff);
+                  *dp++ = (png_byte)d;
                   d = 0;
                }
 
@@ -2262,7 +2262,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
                   shift -= 4;
             }
             if (shift != 4)
-               *dp = (png_byte)(d & 0xff);
+               *dp = (png_byte)d;
 
             break;
          }
@@ -2453,7 +2453,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (lp = row_buf + 1; i < row_bytes;
          i++, rp++, lp++, dp++)
       {
-         *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+         *dp = (png_byte)((int)*rp - (int)*lp);
       }
 
       best_row = png_ptr->sub_row;
@@ -2515,7 +2515,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (lp = row_buf + 1; i < row_bytes;
          i++, rp++, lp++, dp++)
       {
-         v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+         v = *dp = (png_byte)((int)*rp - (int)*lp);
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -2574,7 +2574,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
           pp = prev_row + 1; i < row_bytes;
           i++, rp++, pp++, dp++)
       {
-         *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
+         *dp = (png_byte)((int)*rp - (int)*pp);
       }
 
       best_row = png_ptr->up_row;
@@ -2625,7 +2625,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
           pp = prev_row + 1; i < row_bytes; i++)
       {
-         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -2683,13 +2683,13 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
            pp = prev_row + 1; i < bpp; i++)
       {
-         *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
+         *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2));
       }
 
       for (lp = row_buf + 1; i < row_bytes; i++)
       {
          *dp++ =
-             (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
+             (png_byte)((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2));
       }
       best_row = png_ptr->avg_row;
    }
@@ -2738,7 +2738,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
            pp = prev_row + 1; i < bpp; i++)
       {
-         v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - ((int)*pp++ / 2));
 
          sum += (v < 128) ? v : 256 - v;
       }
@@ -2746,7 +2746,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (lp = row_buf + 1; i < row_bytes; i++)
       {
          v = *dp++ =
-             (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
+             (png_byte)(((int)*rp++ - ((int)*pp++ + (int)*lp++) / 2));
 
          sum += (v < 128) ? v : 256 - v;
 
@@ -2804,7 +2804,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
           pp = prev_row + 1; i < bpp; i++)
       {
-         *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+         *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
       }
 
       for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
@@ -2830,7 +2830,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 
          p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
 
-         *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
+         *dp++ = (png_byte)((int)*rp++ - p);
       }
       best_row = png_ptr->paeth_row;
    }
@@ -2879,7 +2879,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
       for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
           pp = prev_row + 1; i < bpp; i++)
       {
-         v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - (int)*pp++);
 
          sum += (v < 128) ? v : 256 - v;
       }
@@ -2921,7 +2921,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
             p = c;
 #endif /* SLOW_PAETH */
 
-         v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
+         v = *dp++ = (png_byte)((int)*rp++ - p);
 
          sum += (v < 128) ? v : 256 - v;
 

projects/vstudio/readme.txt

@@ -1,7 +1,7 @@
 
 VisualStudio instructions
 
-libpng version 1.6.17rc04 - March 16, 2015
+libpng version 1.6.18beta01 - April 1, 2015
 
 Copyright (c) 1998-2010 Glenn Randers-Pehrson
 

projects/vstudio/zlib.props

@@ -2,7 +2,7 @@
 <!--
  * zlib.props - location of zlib source
  *
- * libpng version 1.6.17rc04 - March 16, 2015
+ * libpng version 1.6.18beta01 - April 1, 2015
  *
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  *

scripts/README.txt

@@ -1,9 +1,9 @@
 
-Makefiles for  libpng version 1.6.17rc04 - March 16, 2015
+Makefiles for  libpng version 1.6.18beta01 - April 1, 2015
 
 pnglibconf.h.prebuilt       =>  Stores configuration settings
  makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.17rc04)
+                       (gcc, creates libpng16.so.16.1.6.18beta01)
  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.16.1.6.17rc04)
+                       creates libpng16.so.16.1.6.18beta01)
  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
  makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.17rc04)
+                       creates libpng16.so.16.1.6.18beta01)
  makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.17rc04)
+                       creates libpng16.so.16.1.6.18beta01)
  makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
  makefile.sunos    =>  Sun makefile
  makefile.32sunu   =>  Sun Ultra 32-bit makefile

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 1.6.17rc04"
+PNG_DFN ";Version 1.6.18beta01"
 
 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
         PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"

scripts/libpng-config-head.in

@@ -11,7 +11,7 @@
 
 # Modeled after libxml-config.
 
-version=1.6.17rc04
+version=1.6.18beta01
 prefix=""
 libdir=""
 libs=""

scripts/libpng.pc.in

@@ -5,6 +5,6 @@ includedir=@includedir@/libpng16
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.17rc04
+Version: 1.6.18beta01
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}

scripts/makefile.cegcc

@@ -23,7 +23,7 @@
 
 VERMAJ = 1
 VERMIN = 6
-VERMIC = 17
+VERMIC = 18
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)

scripts/makefile.linux

@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 17
+RELEASE = 18
 
 # Shared library names:
 LIBSO=$(LIBNAME).so

scripts/makefile.msys

@@ -18,7 +18,7 @@ exec_prefix=$(prefix)
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 17
+RELEASE = 18
 
 # Shared library names:
 LIBSO=$(LIBNAME).dll

scripts/makefile.ne12bsd

@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include/libpng16
 
 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.17rc04
+SHLIB_MINOR=	1.6.18beta01
 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

scripts/makefile.netbsd

@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include
 
 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.17rc04
+SHLIB_MINOR=	1.6.18beta01
 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

scripts/makefile.openbsd

@@ -11,7 +11,7 @@ LIBDIR=	${PREFIX}/lib
 MANDIR= ${PREFIX}/man/cat
 
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.17rc04
+SHLIB_MINOR=	1.6.18beta01
 
 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \

scripts/pnglibconf.h.prebuilt

@@ -1,8 +1,8 @@
-/* libpng 1.6.17rc04 STANDARD API DEFINITION */
+/* libpng 1.6.18beta01 STANDARD API DEFINITION */
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng version 1.6.17rc04 - March 16, 2015 */
+/* Libpng version 1.6.18beta01 - April 1, 2015 */
 
 /* Copyright (c) 1998-2014 Glenn Randers-Pehrson */
 
@@ -101,8 +101,6 @@
 #define PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_SEQUENTIAL_READ_SUPPORTED
 #define PNG_SETJMP_SUPPORTED
-#define PNG_SET_CHUNK_CACHE_LIMIT_SUPPORTED
-#define PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
 #define PNG_SET_OPTION_SUPPORTED
 #define PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
 #define PNG_SET_USER_LIMITS_SUPPORTED

scripts/pnglibconf.mak

@@ -49,6 +49,7 @@ pnglibconf.dfn: $(srcdir)/scripts/pnglibconf.dfa $(srcdir)/scripts/options.awk $
 	$(MOVE) pnglibconf.tmp $@
 
 clean-pnglibconf:
-	$(DELETE) pnglibconf.h pnglibconf.c pnglibconf.out
+	$(DELETE) pnglibconf.h pnglibconf.c pnglibconf.out pnglibconf.pre \
+	pnglibconf.dfn
 
 clean: clean-pnglibconf

scripts/symbols.def

@@ -1,4 +1,4 @@
-;Version 1.6.17rc04
+;Version 1.6.18beta01
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng