[master] Imported from libpng-1.6.17.tar

[master] Imported from libpng-1.6.16.tar
[master] Imported from libpng-1.6.15.tar
2025-07-10 18:04:09 +02:00 · 2015-03-26 08:11:22 -05:00 · 2015-01-15 12:47:40 -05:00 · 2014-11-20 10:23:30 -06:00 · 2014-10-22 19:33:27 -05:00 · 2014-08-21 05:59:56 -05:00
42 changed files with 231 additions and 1996 deletions
--- a/79
+++ b/79
@@ -1,50 +1,67 @@
-Libpng 1.6.18beta03 - May 6, 2015
+Libpng 1.6.17 - March 26, 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.
+This is a public release of libpng, intended for use in production codes.

 Files available for download:

 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script

-   1.6.18beta03.tar.xz (LZMA-compressed, recommended)
-   1.6.18beta03.tar.gz
+   libpng-1.6.17.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.17.tar.gz

 Source files with CRLF line endings (for Windows), without the
 "configure" script

-   lp1618b03.7z  (LZMA-compressed, recommended)
-   lp1618b03.zip
+   lpng1617.7z  (LZMA-compressed, recommended)
+   lpng1617.zip

 Other information:

-   1.6.18beta03-README.txt
-   1.6.18beta03-LICENSE.txt
-   libpng-1.6.18beta03-*.asc (armored detached GPG signatures)
+   libpng-1.6.17-README.txt
+   libpng-1.6.17-LICENSE.txt
+   libpng-1.6.17-*.asc (armored detached GPG signatures)

-Changes since the last public release (1.6.17):
+Changes since the last public release (1.6.16):

-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 (Bug reports by Peter Breitenlohner [i686]
-    and Petr Gajdos [i586]).
-
-Version 1.6.18beta02 [April 26, 2015]
-  Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
-    (Bug report by Viktor Szaka'ts).
-
-Version 1.6.18beta03 [May 6, 2015]
-  Replaced "unexpected" with an integer (0xabadca11) in pngset.c
-    where a long was expected, to avoid a compiler warning when PNG_DEBUG > 1.
-  Added contrib/examples/simpleover.c, to demonstrate how to handle
-    alpha compositing of multiple images, using the "simplified API"
-    and an example PNG generation tool, contrib/examples/genpng.c
-    (John Bowler).
+  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.
+  Do not build png_product2() when it is unused.
+  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.
+  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
+  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)
+  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.
+  Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
+    for consistency, and remove some useless tests (Alexey Petruchik).
+  Remove pnglibconf.h, pnglibconf.c, pnglibconf.pre, pnglibconf.dfn,
+    and pnglibconf.out instead of pnglibconf.* in "make clean" (Cosmin).
+  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).

 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
--- a/23
+++ b/23
@@ -5141,7 +5141,7 @@ Version 1.6.17beta01 [January 29, 2015]
  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 warnings.
+    to (png_byte), to avoid Coverity gripes.

 Version 1.6.17beta02 [February 7, 2015]
  Work around one more Coverity-scan dead-code warning.
@@ -5205,27 +5205,6 @@ Version 1.6.17rc06 [March 23, 2015]
 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 (Bug reports by Peter Breitenlohner [i686]
-    and Petr Gajdos [i586]).
-
-Version 1.6.18beta02 [April 26, 2015]
-  Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
-    (Bug report by Viktor Szaka'ts).
-
-Version 1.6.18beta03 [May 6, 2015]
-  Replaced "unexpected" with an integer (0xabadca11) in pngset.c
-    where a long was expected, to avoid a compiler warning when PNG_DEBUG > 1.
-  Added contrib/examples/simpleover.c, to demonstrate how to handle
-    alpha compositing of multiple images, using the "simplified API"
-    and an example PNG generation tool, contrib/examples/genpng.c
-    (John Bowler).
-
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,7 +16,7 @@ enable_testing()

 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 18)
+set(PNGLIB_RELEASE 17)
 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}.1.6.18beta03
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.17
    VERSION 16.${PNGLIB_RELEASE}.0
    SOVERSION 16
    CLEAN_DIRECT_OUTPUT 1)
--- a/4
+++ b/4
@@ -10,7 +10,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.2.6, August 15, 2004, through 1.6.18beta03, May 6, 2015, are
+libpng versions 1.2.6, August 15, 2004, through 1.6.17, March 26, 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
-May 6, 2015
+March 26, 2015
--- a/2
+++ b/2
@@ -1,4 +1,4 @@
-README for libpng version 1.6.18beta03 - May 6, 2015 (shared library 16.0)
+README for libpng version 1.6.17 - March 26, 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.
--- a/autogen.sh
+++ b/autogen.sh
@@ -73,9 +73,8 @@ done
 # present bad things are happening.
 #
 # The autotools generated files:
-libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
-   config.h.in~ config.sub configure depcomp install-sh ltmain.sh missing\
-   test-driver"
+libpng_autotools_files="Makefile.in aclocal.m4 config.guess 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):
--- a/configure.ac
+++ b/configure.ac
@@ -18,7 +18,7 @@ AC_PREREQ([2.68])

 dnl Version number stuff here:

-AC_INIT([libpng],[1.6.18beta03],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.17],[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=1.6.18beta03
+PNGLIB_VERSION=1.6.17
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=18
+PNGLIB_RELEASE=17

 dnl End of version number stuff

--- a/contrib/examples/simpleover.c
+++ b/contrib/examples/simpleover.c
@@ -1,645 +0,0 @@
-/*- simpleover
- *
- * COPYRIGHT: Written by John Cunningham Bowler, 2015.
- * To the extent possible under law, the author has waived all copyright and
- * related or neighboring rights to this work.  This work is published from:
- * United States.
- *
- * Read several PNG files, which should have an alpha channel or transparency
- * information, and composite them together to produce one or more 16-bit linear
- * RGBA intermediates.  This involves doing the correct 'over' composition to
- * combine the alpha channels and corresponding data.
- *
- * Finally read an output (background) PNG using the 24-bit RGB format (the
- * PNG will be composited on green (#00ff00) by default if it has an alpha
- * channel), and apply the intermediate image generated above to specified
- * locations in the image.
- *
- * The command line has the general format:
- *
- *    simpleover <background.png> [output.png]
- *        {--sprite=width,height,name {[--at=x,y] {sprite.png}}}
- *        {--add=name {x,y}}
- *
- * The --sprite and --add options may occur multiple times. They are executed
- * in order.  --add may refer to any sprite already read.
- *
- * This code is intended to show how to composite multiple images together
- * correctly.  Apart from the libpng Simplified API the only work done in here
- * is to combine multiple input PNG images into a single sprite; this involves
- * a Porter-Duff 'over' operation and the input PNG images may, as a result,
- * be regarded as being layered one on top of the other with the first (leftmost
- * on the command line) being at the bottom and the last on the top.
- */
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <errno.h>
-
-/* Normally use <png.h> here to get the installed libpng, but this is done to
- * ensure the code picks up the local libpng implementation, so long as this
- * file is linked against a sufficiently recent libpng (1.6+) it is ok to
- * change this to <png.h>:
- */
-#include "../../png.h"
-
-#define sprite_name_chars 15
-struct sprite {
-   FILE         *file;
-   png_uint_16p  buffer;
-   unsigned int  width;
-   unsigned int  height;
-   char          name[sprite_name_chars+1];
-};
-
-#if 0 /* div by 65535 test program */
-#include <math.h>
-#include <stdio.h>
-
-int main(void) {
-   double err = 0;
-   unsigned int xerr = 0;
-   unsigned int r = 32769;
-   {
-      unsigned int x = 0;
-
-      do {
-         unsigned int t = x + (x >> 16) /*+ (x >> 31)*/ + r;
-         double v = x, errtest;
-
-         if (t < x) {
-            fprintf(stderr, "overflow: %u+%u -> %u\n", x, r, t);
-            return 1;
-         }
-
-         v /= 65535;
-         errtest = v;
-         t >>= 16;
-         errtest -= t;
-
-         if (errtest > err) {
-            err = errtest;
-            xerr = x;
-
-            if (errtest >= .5) {
-               fprintf(stderr, "error: %u/65535 = %f, not %u, error %f\n",
-                     x, v, t, errtest);
-               return 0;
-            }
-         }
-      } while (++x <= 65535U*65535U);
-   }
-
-   printf("error %f @ %u\n", err, xerr);
-
-   return 0;
-}
-#endif /* div by 65535 test program */
-
-static void
-sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
-   png_imagep image, const png_uint_16 *buffer)
-{
-   /* This is where the Porter-Duff 'Over' operator is evaluated; change this
-    * code to change the operator (this could be parameterized).  Any other
-    * image processing operation could be used here.
-    */
-
-
-   /* Check for an x or y offset that pushes any part of the image beyond the
-    * right or bottom of the sprite:
-    */
-   if ((y_offset < 0 || (unsigned)/*SAFE*/y_offset < sprite->height) &&
-       (x_offset < 0 || (unsigned)/*SAFE*/x_offset < sprite->width))
-   {
-      unsigned int y = 0;
-
-      if (y_offset < 0)
-         y = -y_offset; /* Skip to first visible row */
-
-      do
-      {
-         unsigned int x = 0;
-
-         if (x_offset < 0)
-            x = -x_offset;
-
-         do
-         {
-            /* In and out are RGBA values, so: */
-            const png_uint_16 *in_pixel = buffer + (y * image->width + x)*4;
-            png_uint_32 in_alpha = in_pixel[3];
-
-            /* This is the optimized Porter-Duff 'Over' operation, when the
-             * input alpha is 0 the output is not changed.
-             */
-            if (in_alpha > 0) 
-            {
-               png_uint_16 *out_pixel = sprite->buffer +
-                  ((y+y_offset) * sprite->width + (x+x_offset))*4;
-
-               /* This is the weight to apply to the output: */
-               in_alpha = 65535-in_alpha;
-
-               if (in_alpha > 0)
-               {
-                  /* The input must be composed onto the output. This means
-                   * multiplying the current output pixel value by the inverse
-                   * of the input alpha (1-alpha). A division is required but
-                   * it is by the constant 65535.  Approximate this as:
-                   *
-                   *     (x + (x >> 16) + 32769) >> 16;
-                   *
-                   * This is exact (and does not overflow) for all values of
-                   * x in the range 0..65535*65535.  (Note that the calculation
-                   * produces the closest integer; the maximum error is <0.5).
-                   */
-                  png_uint_32 tmp;
-
-#                 define compose(c)\
-                     tmp = out_pixel[c] * in_alpha;\
-                     tmp = (tmp + (tmp >> 16) + 32769) >> 16;\
-                     out_pixel[c] = tmp + in_pixel[c]
-
-                  /* The following is very vectorizable... */
-                  compose(0);
-                  compose(1);
-                  compose(2);
-                  compose(3);
-               }
-
-               else
-                  out_pixel[0] = in_pixel[0],
-                  out_pixel[1] = in_pixel[1],
-                  out_pixel[2] = in_pixel[2],
-                  out_pixel[3] = in_pixel[3];
-            }
-         }
-         while (++x < image->width);
-      }
-      while (++y < image->height);
-   }
-}
-
-static int 
-create_sprite(struct sprite *sprite, int *argc, const char ***argv)
-{
-   /* Read the arguments and create this sprite. The sprite buffer has already
-    * been allocated. This reads the input PNGs one by one in linear format,
-    * composes them onto the sprite buffer (the code in the function above)
-    * then saves the result, converting it on the fly to PNG RGBA 8-bit format.
-    */
-   while (*argc > 0)
-   {
-      char tombstone;
-      int x = 0, y = 0;
-
-      if ((*argv)[0][0] == '-' && (*argv)[0][1] == '-')
-      {
-         /* The only supported option is --at. */
-         if (sscanf((*argv)[0], "--at=%d,%d%c", &x, &y, &tombstone) != 2)
-            break; /* success; caller will parse this option */
-
-         ++*argv, --*argc;
-      }
-
-      else
-      {
-         /* The argument has to be a file name */
-         png_image image;
-
-         image.version = PNG_IMAGE_VERSION;
-         image.opaque = NULL;
-
-         if (png_image_begin_read_from_file(&image, (*argv)[0]))
-         {
-            png_uint_16p buffer;
-
-            image.format = PNG_FORMAT_LINEAR_RGB_ALPHA;
-
-            buffer = malloc(PNG_IMAGE_SIZE(image));
-
-            if (buffer != NULL)
-            {
-               if (png_image_finish_read(&image, NULL/*background*/, buffer,
-                  0/*row_stride*/,
-                  NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
-               {
-                  /* This is the place where the Porter-Duff 'Over' operator
-                   * needs to be done by this code.  In fact, any image
-                   * processing required can be done here; the data is in
-                   * the correct format (linear, 16-bit) and source and
-                   * destination are in memory.
-                   */
-                  sprite_op(sprite, x, y, &image, buffer);
-                  free(buffer);
-                  ++*argv, --*argc;
-                  /* And continue to the next argument */
-                  continue;
-               }
-
-               else
-               {
-                  free(buffer);
-                  fprintf(stderr, "simpleover: read %s: %s\n", (*argv)[0],
-                      image.message);
-               }
-            }
-
-            else
-            {
-               fprintf(stderr, "simpleover: out of memory: %lu bytes\n",
-                  (unsigned long)PNG_IMAGE_SIZE(image));
-
-               /* png_image_free must be called if we abort the Simplified API
-                * read because of a problem detected in this code.  If problems
-                * are detected in the Simplified API it cleans up itself.
-                */
-               png_image_free(&image);
-            }
-         }
-
-         else
-         {
-            /* Failed to read the first argument: */
-            fprintf(stderr, "simpleover: %s: %s\n", (*argv)[0], image.message);
-         }
-
-         return 0; /* failure */
-      }
-   }
-
-   /* All the sprite operations have completed successfully. Save the RGBA
-    * buffer as a PNG using the simplified write API.
-    */
-   sprite->file = tmpfile();
-
-   if (sprite->file != NULL)
-   {
-      png_image save;
-
-      memset(&save, 0, sizeof save);
-      save.version = PNG_IMAGE_VERSION;
-      save.opaque = NULL;
-      save.width = sprite->width;
-      save.height = sprite->height;
-      save.format = PNG_FORMAT_LINEAR_RGB_ALPHA;
-      save.flags = PNG_IMAGE_FLAG_FAST;
-      save.colormap_entries = 0;
-
-      if (png_image_write_to_stdio(&save, sprite->file, 1/*convert_to_8_bit*/,
-          sprite->buffer, 0/*row_stride*/, NULL/*colormap*/))
-      {
-         /* Success; the buffer is no longer needed: */
-         free(sprite->buffer);
-         sprite->buffer = NULL;
-         return 1; /* ok */
-      }
-
-      else
-         fprintf(stderr, "simpleover: write sprite %s: %s\n", sprite->name,
-            save.message);
-   }
-
-   else
-      fprintf(stderr, "simpleover: sprite %s: could not allocate tmpfile: %s\n",
-         sprite->name, strerror(errno));
-
-   return 0; /* fail */
-}
-
-static int
-add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
-   int *argc, const char ***argv)
-{
-   /* Given a --add argument naming this sprite, perform the operations listed
-    * in the following arguments.  The arguments are expected to have the form
-    * (x,y), which is just an offset at which to add the sprite to the
-    * output.
-    */
-   while (*argc > 0)
-   {
-      char tombstone;
-      int x, y;
-
-      if ((*argv)[0][0] == '-' && (*argv)[0][1] == '-')
-         return 1; /* success */
-
-      if (sscanf((*argv)[0], "%d,%d%c", &x, &y, &tombstone) == 2)
-      {
-         /* Now add the new image into the sprite data, but only if it
-          * will fit.
-          */
-         if (x < 0 || y < 0 ||
-             (unsigned)/*SAFE*/x >= output->width ||
-             (unsigned)/*SAFE*/y >= output->height ||
-             sprite->width > output->width-x ||
-             sprite->height > output->height-y)
-         {
-            fprintf(stderr, "simpleover: sprite %s @ (%d,%d) outside image\n",
-               sprite->name, x, y);
-            /* Could just skip this, but for the moment it is an error */
-            return 0; /* error */
-         }
-
-         else
-         {
-            /* Since we know the sprite fits we can just read it into the
-             * output using the simplified API.
-             */
-            png_image in;
-
-            in.version = PNG_IMAGE_VERSION;
-            rewind(sprite->file);
-
-            if (png_image_begin_read_from_stdio(&in, sprite->file))
-            {
-               in.format = PNG_FORMAT_RGB; /* force compose */
-
-               if (png_image_finish_read(&in, NULL/*background*/,
-                  out_buf + (y*output->width + x)*3/*RGB*/,
-                  output->width*3/*row_stride*/,
-                  NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
-               {
-                  ++*argv, --*argc;
-                  continue;
-               }
-            }
-
-            /* The read failed: */
-            fprintf(stderr, "simpleover: add sprite %s: %s\n", sprite->name,
-                in.message);
-            return 0; /* error */
-         }
-      }
-
-      else
-      {
-         fprintf(stderr, "simpleover: --add='%s': invalid position %s\n",
-               sprite->name, (*argv)[0]);
-         return 0; /* error */
-      }
-   }
-
-   return 1; /* ok */
-}
-
-static int
-simpleover_process(png_imagep output, png_bytep out_buf, int argc,
-   const char **argv)
-{
-   int result = 1; /* success */
-#  define csprites 10/*limit*/
-#  define str(a) #a
-   int nsprites = 0;
-   struct sprite sprites[csprites];
-
-   while (argc > 0)
-   {
-      result = 0; /* fail */
-
-      if (strncmp(argv[0], "--sprite=", 9) == 0)
-      {
-         char tombstone;
-
-         if (nsprites < csprites)
-         {
-            int n;
-
-            sprites[nsprites].width = sprites[nsprites].height = 0;
-            sprites[nsprites].name[0] = 0;
-
-            n = sscanf(argv[0], "--sprite=%u,%u,%" str(sprite_name_chars) "s%c",
-                &sprites[nsprites].width, &sprites[nsprites].height,
-                sprites[nsprites].name, &tombstone);
-            
-            if ((n == 2 || n == 3) &&
-                sprites[nsprites].width > 0 && sprites[nsprites].height > 0)
-            {
-               size_t buf_size, tmp;
-
-               /* Default a name if not given. */
-               if (sprites[nsprites].name[0] == 0)
-                  sprintf(sprites[nsprites].name, "sprite-%d", nsprites+1);
-
-               /* Allocate a buffer for the sprite and calculate the buffer
-                * size:
-                */
-               buf_size = sizeof (png_uint_16 [4]);
-               buf_size *= sprites[nsprites].width;
-               buf_size *= sprites[nsprites].height;
-
-               /* This can overflow a (size_t); check for this: */
-               tmp = buf_size;
-               tmp /= sprites[nsprites].width;
-               tmp /= sprites[nsprites].height;
-
-               if (tmp == sizeof (png_uint_16 [4]))
-               {
-                  sprites[nsprites].buffer = malloc(buf_size);
-                  /* This buffer must be initialized to transparent: */
-                  memset(sprites[nsprites].buffer, 0, buf_size);
-
-                  if (sprites[nsprites].buffer != NULL)
-                  {
-                     sprites[nsprites].file = NULL;
-                     ++argv, --argc;
-
-                     if (create_sprite(sprites+nsprites++, &argc, &argv))
-                     {
-                        result = 1; /* still ok */
-                        continue;
-                     }
-
-                     break; /* error */
-                  }
-               }
-
-               /* Overflow, or OOM */
-               fprintf(stderr, "simpleover: %s: sprite too large\n", argv[0]);
-               break;
-            }
-
-            else
-            {
-               fprintf(stderr, "simpleover: %s: invalid sprite (%u,%u)\n",
-                  argv[0], sprites[nsprites].width, sprites[nsprites].height);
-               break;
-            }
-         }
-
-         else
-         {
-            fprintf(stderr, "simpleover: %s: too many sprites\n", argv[0]);
-            break;
-         }
-      }
-
-      else if (strncmp(argv[0], "--add=", 6) == 0)
-      {
-         const char *name = argv[0]+6;
-         int isprite = nsprites;
-
-         ++argv, --argc;
-
-         while (--isprite >= 0)
-         {
-            if (strcmp(sprites[isprite].name, name) == 0)
-            {
-               if (!add_sprite(output, out_buf, sprites+isprite, &argc, &argv))
-                  goto out; /* error in add_sprite */
-
-               break; 
-            }
-         }
-
-         if (isprite < 0) /* sprite not found */
-         {
-            fprintf(stderr, "simpleover: --add='%s': sprite not found\n", name);
-            break;
-         }
-      }
-
-      else
-      {
-         fprintf(stderr, "simpleover: %s: unrecognized operation\n", argv[0]);
-         break;
-      }
-
-      result = 1; /* ok  */
-   }
-
-   /* Clean up the cache of sprites: */
-out:
-   while (--nsprites >= 0)
-   {
-      if (sprites[nsprites].buffer != NULL)
-         free(sprites[nsprites].buffer);
-
-      if (sprites[nsprites].file != NULL)
-         (void)fclose(sprites[nsprites].file);
-   }
-
-   return result;
-}
-
-int main(int argc, const char **argv)
-{
-   int result = 1; /* default to fail */
-
-   if (argc >= 2)
-   {
-      int argi = 2;
-      const char *output = NULL;
-      png_image image;
-
-      if (argc > 2 && argv[2][0] != '-'/*an operation*/)
-      {
-         output = argv[2];
-         argi = 3;
-      }
-
-      image.version = PNG_IMAGE_VERSION;
-      image.opaque = NULL;
-
-      if (png_image_begin_read_from_file(&image, argv[1]))
-      {
-         png_bytep buffer;
-
-         image.format = PNG_FORMAT_RGB; /* 24-bit RGB */
-
-         buffer = malloc(PNG_IMAGE_SIZE(image));
-
-         if (buffer != NULL)
-         {
-            png_color background = {0, 0xff, 0}; /* fully saturated green */
-
-            if (png_image_finish_read(&image, &background, buffer,
-               0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
-            {
-               /* At this point png_image_finish_read has cleaned up the
-                * allocated data in png_image, and only the buffer needs to be
-                * freed.
-                *
-                * Perform the remaining operations:
-                */
-               if (simpleover_process(&image, buffer, argc-argi, argv+argi))
-               {
-                  /* Write the output: */
-                  if ((output != NULL &&
-                       png_image_write_to_file(&image, output,
-                        0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
-                        NULL/*colormap*/)) ||
-                      (output == NULL &&
-                       png_image_write_to_stdio(&image, stdout,
-                        0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
-                        NULL/*colormap*/)))
-                     result = 0;
-
-                  else
-                     fprintf(stderr, "simpleover: write %s: %s\n",
-                        output == NULL ? "stdout" : output, image.message);
-               }
-
-               /* else simpleover_process writes an error message */
-            }
-
-            else
-               fprintf(stderr, "simpleover: read %s: %s\n", argv[1],
-                   image.message);
-
-            free(buffer);
-         }
-
-         else
-         {
-            fprintf(stderr, "simpleover: out of memory: %lu bytes\n",
-               (unsigned long)PNG_IMAGE_SIZE(image));
-
-            /* This is the only place where a 'free' is required; libpng does
-             * the cleanup on error and success, but in this case we couldn't
-             * complete the read because of running out of memory.
-             */
-            png_image_free(&image);
-         }
-      }
-
-      else
-      {
-         /* Failed to read the first argument: */
-         fprintf(stderr, "simpleover: %s: %s\n", argv[1], image.message);
-      }
-   }
-
-   else
-   {
-      /* Usage message */
-      fprintf(stderr,
-         "simpleover: usage: simpleover background.png [output.png]\n"
-         "  Output 'background.png' as a 24-bit RGB PNG file in 'output.png'\n"
-         "   or, if not given, stdout.  'background.png' will be composited\n"
-         "   on fully saturated green.\n"
-         "\n"
-         "  Optionally, before output, process additional PNG files:\n"
-         "\n"
-         "   --sprite=width,height,name {[--at=x,y] {sprite.png}}\n"
-         "    Produce a transparent sprite of size (width,height) and with\n"
-         "     name 'name'.\n"
-         "    For each sprite.png composite it using a Porter-Duff 'Over'\n"
-         "     operation at offset (x,y) in the sprite (defaulting to (0,0)).\n"
-         "     Input PNGs will be truncated to the area of the sprite.\n"
-         "\n"
-         "   --add='name' {x,y}\n"
-         "    Optionally, before output, composite a sprite, 'name', which\n"
-         "     must have been previously produced using --sprite, at each\n"
-         "     offset (x,y) in the output image.  Each sprite must fit\n"
-         "     completely within the output image.\n"
-         "\n"
-         "  PNG files are processed in the order they occur on the command\n"
-         "  line and thus the first PNG processed appears as the bottommost\n"
-         "  in the output image.\n");
-   }
-
-   return result;
-}
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,7 +1,7 @@

 /* pngvalid.c - validate libpng by constructing then reading png files.
 *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 2015]
 * Copyright (c) 2014-2015 Glenn Randers-Pehrson
 * Written by John Cunningham Bowler
 *
@@ -258,7 +258,7 @@ make_four_random_bytes(png_uint_32* seed, png_bytep bytes)
   make_random_bytes(seed, bytes, 4);
 }

-#if defined PNG_READ_SUPPORTED || defined PNG_WRITE_tRNS_SUPPORTED
+#ifdef PNG_READ_SUPPORTED
 static void
 randomize(void *pv, size_t size)
 {
@@ -267,9 +267,7 @@ 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)
 {
@@ -297,8 +295,7 @@ 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 otherwise a boolean
- * indicating if a tRNS chunk was generated.
+ * index of the palette to use for formats with a palette (0 otherwise.)
 */
 #define FILEID(col, depth, palette, interlace, width, height, do_interlace) \
   ((png_uint_32)((col) + ((depth)<<3) + ((palette)<<8) + ((interlace)<<13) + \
@@ -319,16 +316,12 @@ 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 (colour_type == 3) /* must have a palette */
+   if (npalette > 0)
   {
      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");
@@ -385,32 +378,25 @@ 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 low_depth_gray, int tRNS)
+   unsigned int* palette_number, int no_low_depth_gray)
 {
   if (*bit_depth == 0)
   {
      *colour_type = 0;
-      if (low_depth_gray)
-         *bit_depth = 1;
-      else
+      if (no_low_depth_gray)
         *bit_depth = 8;
+      else
+         *bit_depth = 1;
      *palette_number = 0;
      return 1;
   }

-   if  (*colour_type < 4/*no alpha channel*/)
+   if (*colour_type == 3)
   {
-      /* 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)))
+      /* Add multiple palettes for colour type 3. */
+      if (++*palette_number < PALETTE_COUNT(*bit_depth))
         return 1;

-      /* No: next bit depth */
      *palette_number = 0;
   }

@@ -1973,7 +1959,6 @@ 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
@@ -2005,16 +1990,6 @@ 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
@@ -2067,11 +2042,6 @@ 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;
@@ -2084,11 +2054,6 @@ 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;

@@ -3227,45 +3192,6 @@ 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:
 */
@@ -3599,11 +3525,6 @@ 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) !=
@@ -3677,20 +3598,19 @@ make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
 }

 static void
-make_transform_images(png_modifier *pm)
+make_transform_images(png_store *ps)
 {
   png_byte colour_type = 0;
   png_byte bit_depth = 0;
   unsigned int palette_number = 0;

   /* This is in case of errors. */
-   safecat(pm->this.test, sizeof pm->this.test, 0, "make standard images");
+   safecat(ps->test, sizeof ps->test, 0, "make standard images");

   /* Use next_format to enumerate all the combinations we test, including
-    * generating multiple low bit depth palette images. Non-A images (palette
-    * and direct) are created with and without tRNS chunks.
+    * generating multiple low bit depth palette images.
    */
-   while (next_format(&colour_type, &bit_depth, &palette_number, 1, 1))
+   while (next_format(&colour_type, &bit_depth, &palette_number, 0))
   {
      int interlace_type;

@@ -3701,7 +3621,7 @@ make_transform_images(png_modifier *pm)

         standard_name(name, sizeof name, 0, colour_type, bit_depth,
            palette_number, interlace_type, 0, 0, 0);
-         make_transform_image(&pm->this, colour_type, bit_depth, palette_number,
+         make_transform_image(ps, colour_type, bit_depth, palette_number,
            interlace_type, name);
      }
   }
@@ -4367,7 +4287,6 @@ 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
@@ -4700,14 +4619,14 @@ 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->has_tRNS = 1;
+            dp->is_transparent = 1;
            break;

         case 2:
            dp->transparent.red = trans_color->red;
            dp->transparent.green = trans_color->green;
            dp->transparent.blue = trans_color->blue;
-            dp->has_tRNS = 1;
+            dp->is_transparent = 1;
            break;

         case 3:
@@ -5599,7 +5518,7 @@ 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 = this->sample_depth = 8;
+            this->bit_depth = 8;

         if (this->have_tRNS)
         {
@@ -5634,11 +5553,9 @@ image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
               this->alphaf = 0;
            else
               this->alphaf = 1;
-         }
-         else
-            this->alphaf = 1;

-         this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
+            this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
+         }
      }

      /* The error in the alpha is zero and the sBIT value comes from the
@@ -5931,9 +5848,8 @@ 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
@@ -6456,13 +6372,6 @@ 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);
 }

@@ -6521,7 +6430,6 @@ 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);
 }

@@ -6581,10 +6489,6 @@ 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);
 }

@@ -6635,7 +6539,6 @@ 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);
 }

@@ -6667,11 +6570,6 @@ 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);
 }

@@ -7042,14 +6940,14 @@ 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 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.
+          * 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.
          */
         that->pm->limit += pow(
 #        if DIGITIZE
-            1.3
+            1.25
 #        else
            1.0
 #        endif
@@ -7213,8 +7111,7 @@ 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 ?
-            PNG_MAX_GAMMA_8 :
+         const unsigned int gamma_depth = (sample_depth == 16 ? 16 :
            (pm->assume_16_bit_calculations ? PNG_MAX_GAMMA_8 : sample_depth));
         int isgray;
         double r, g, b;
@@ -7228,73 +7125,56 @@ 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 = DD(rlo, calc_depth, 1/*round*/);
+         rlo = digitize(rlo, calc_depth, 1/*round*/);
         rhi += that->rede;
-         rhi = DU(rhi, calc_depth, 1/*round*/);
+         rhi = digitize(rhi, calc_depth, 1/*round*/);

         g = glo = ghi = that->greenf;
         glo -= that->greene;
-         glo = DD(glo, calc_depth, 1/*round*/);
+         glo = digitize(glo, calc_depth, 1/*round*/);
         ghi += that->greene;
-         ghi = DU(ghi, calc_depth, 1/*round*/);
+         ghi = digitize(ghi, calc_depth, 1/*round*/);

         b = blo = bhi = that->bluef;
         blo -= that->bluee;
-         blo = DD(blo, calc_depth, 1/*round*/);
+         blo = digitize(blo, calc_depth, 1/*round*/);
         bhi += that->greene;
-         bhi = DU(bhi, calc_depth, 1/*round*/);
+         bhi = digitize(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 = .5/(sample_depth == 16 ? 65535 : 255);
+            PNG_CONST double abse = calc_depth == 16 ? .5/65535 : .5/255;

-            /* 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.
+            /* '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 (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 = DD(pow(rlo, power)-abse, calc_depth, 1);
-            rhi = DU(pow(rhi, power)+abse, calc_depth, 1);
+            rlo = digitize(pow(rlo, power)-abse, calc_depth, 1);
+            rhi = digitize(pow(rhi, power)+abse, calc_depth, 1);

            g = pow(g, power);
-            glo = DD(pow(glo, power)-abse, calc_depth, 1);
-            ghi = DU(pow(ghi, power)+abse, calc_depth, 1);
+            glo = digitize(pow(glo, power)-abse, calc_depth, 1);
+            ghi = digitize(pow(ghi, power)+abse, calc_depth, 1);

            b = pow(b, power);
-            blo = DD(pow(blo, power)-abse, calc_depth, 1);
-            bhi = DU(pow(bhi, power)+abse, calc_depth, 1);
+            blo = digitize(pow(blo, power)-abse, calc_depth, 1);
+            bhi = digitize(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
-          * 2/32768, because even in the rounding case the requirement that
+          * 1/32768, 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
@@ -7305,19 +7185,19 @@ 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 = 2. / 32768;
+            PNG_CONST double ce = 1. / 32768;

-            graylo = DD(rlo * (data.red_coefficient-ce) +
+            graylo = digitize(rlo * (data.red_coefficient-ce) +
               glo * (data.green_coefficient-ce) +
-               blo * (data.blue_coefficient-ce), calc_depth, do_round);
-            if (graylo > gray) /* always accept the right answer */
-               graylo = gray;
+               blo * (data.blue_coefficient-ce), gamma_depth, do_round);
+            if (graylo <= 0)
+               graylo = 0;

-            grayhi = DU(rhi * (data.red_coefficient+ce) +
+            grayhi = digitize(rhi * (data.red_coefficient+ce) +
               ghi * (data.green_coefficient+ce) +
-               bhi * (data.blue_coefficient+ce), calc_depth, do_round);
-            if (grayhi < gray)
-               grayhi = gray;
+               bhi * (data.blue_coefficient+ce), gamma_depth, do_round);
+            if (grayhi >= 1)
+               grayhi = 1;
         }

         /* And invert the gamma. */
@@ -7325,25 +7205,11 @@ 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 = DD(pow(graylo, power), sample_depth, 1);
-            grayhi = DU(pow(grayhi, power), sample_depth, 1);
+            graylo = digitize(pow(graylo, power), sample_depth, 1);
+            grayhi = digitize(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
@@ -7394,28 +7260,16 @@ 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 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.)
+             * 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.)
             */
            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 + 2./32768 + gray * 5 * DBL_EPSILON;
+               be * data.blue_coefficient + 1./32768 + gray * 5 * DBL_EPSILON;
         }

         else
@@ -7450,7 +7304,7 @@ 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 - 2./32768 - out_qe;
+               b * data.blue_coefficient - 1./32768 - out_qe;
            if (gray <= 0)
               gray = 0;
            else
@@ -7460,7 +7314,7 @@ 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 + 2./32768 + out_qe;
+               bhi * data.blue_coefficient + 1./32768 + out_qe;
            grayhi *= (1 + 6 * DBL_EPSILON);
            if (grayhi >= 1)
               grayhi = 1;
@@ -7575,9 +7429,6 @@ 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;
   }
@@ -7655,13 +7506,13 @@ 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);
 }
@@ -8450,8 +8301,7 @@ 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, pm->test_lbg,
-            pm->test_tRNS))
+   while (next_format(&colour_type, &bit_depth, &palette_number, 0))
   {
      png_uint_32 counter = 0;
      size_t base_pos;
@@ -8754,9 +8604,7 @@ 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 == 0 || dp->this.colour_type == 2) &&
-       dp->this.has_tRNS))
+      (dp->this.colour_type == 3 && dp->this.is_transparent))
   {
      vi->do_background = dp->do_background;

@@ -8786,7 +8634,7 @@ init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
         vi->background_blue = b;
      }
   }
-   else /* Do not expect any background processing */
+   else
      vi->do_background = 0;

   if (vi->do_background == 0)
@@ -9502,7 +9350,6 @@ 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;
@@ -9518,7 +9365,6 @@ 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
@@ -9557,8 +9403,8 @@ 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 :
@@ -9590,35 +9436,6 @@ 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,
@@ -9728,7 +9545,7 @@ gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn,

      modification_reset(d.pm->modifications);

-      /* Get a png_struct for reading the image. */
+      /* Get a png_struct for writing the image. */
      pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
      standard_palette_init(&d.this);

@@ -9867,13 +9684,9 @@ 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,
-                      pm->test_lbg_gamma_threshold, pm->test_tRNS))
-      if (palette_number < 2)
+   while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
+      if (palette_number == 0)
   {
      double test_gamma = 1.0;
      while (test_gamma >= .4)
@@ -9933,8 +9746,7 @@ 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,
-                      pm->test_lbg_gamma_transform, pm->test_tRNS))
+   while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
   {
      unsigned int i, j;

@@ -9964,8 +9776,7 @@ 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,
-                         pm->test_lbg_gamma_sbit, pm->test_tRNS))
+      while (next_format(&colour_type, &bit_depth, &npalette, 1/*gamma*/))
         if ((colour_type & PNG_COLOR_MASK_ALPHA) == 0 &&
            ((colour_type == 3 && sbit < 8) ||
            (colour_type != 3 && sbit < bit_depth)))
@@ -10156,17 +9967,8 @@ 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.
       */
@@ -10215,18 +10017,9 @@ 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,
-                      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))
+   while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
+      if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0)
   {
      unsigned int i, j;

@@ -10958,18 +10751,6 @@ 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);
@@ -11082,7 +10863,7 @@ 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; /* composition */
+         pm.test_gamma_background = 1;
         pm.test_gamma_alpha_mode = 1;
         }

@@ -11131,24 +10912,6 @@ 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;

@@ -11339,7 +11102,7 @@ int main(int argc, char **argv)
   Try
   {
      /* Make useful base images */
-      make_transform_images(&pm);
+      make_transform_images(&pm.this);

      /* Perform the standard and gamma tests. */
      if (pm.test_standard)
--- a/contrib/tools/genpng.c
+++ b/contrib/tools/genpng.c
@@ -1,864 +0,0 @@
-/*- genpng
- *
- * COPYRIGHT: Written by John Cunningham Bowler, 2015.
- * To the extent possible under law, the author has waived all copyright and
- * related or neighboring rights to this work.  This work is published from:
- * United States.
- *
- * Generate a PNG with an alpha channel, correctly.
- *
- * This is a test case generator; the resultant PNG files are only of interest
- * to those of us who care about whether the edges of circles are green, red,
- * or yellow.
- *
- * The program generates an RGB+Alpha PNG of a given size containing the given
- * shapes on a transparent background:
- *
- *  genpng width height { shape }
- *    shape ::= color width shape x1 y1 x2 y2
- *
- * 'color' is:
- *
- *  black white red green yellow blue brown purple pink orange gray cyan
- *
- * The point is to have colors that are linguistically meaningful plus that old
- * bugbear of the department store dress murders, Cyan, the only color we argue
- * about.
- *
- * 'shape' is:
- *
- *  circle: an ellipse
- *  square: a rectangle
- *  line: a straight line
- *
- * Each shape is followed by four numbers, these are two points in the output
- * coordinate space (as real numbers) which describe the circle, square, or
- * line.  The shape is filled if it is preceded by 'filled' (not valid for
- * 'line') or is drawn with a line, in which case the width of the line must
- * precede the shape.
- *
- * The whole set of information can be repeated as many times as desired:
- *
- *    shape ::= color width shape x1 y1 x2 y2
- *
- *    color ::= black|white|red|green|yellow|blue
- *    color ::= brown|purple|pink|orange|gray|cyan
- *    width ::= filled
- *    width ::= <number>
- *    shape ::= circle|square|line
- *    x1    ::= <number>
- *    x2    ::= <number>
- *    y1    ::= <number>
- *    y2    ::= <number>
- *
- * The output PNG is generated by down-sampling a 4x supersampled image using
- * a bi-cubic filter.  The bi-cubic has a 2 (output) pixel width, so an 8x8
- * array of super-sampled points contribute to each output pixel.  The value of
- * a super-sampled point is found using an unfiltered, aliased, infinite
- * precision image: Each shape from the last to the first is checked to see if
- * the point is in the drawn area and, if it is, the color of the point is the
- * color of the shape and the alpha is 1, if not the previous shape is checked.
- *
- * This is an aliased algorithm because no filtering is done; a point is either
- * inside or outside each shape and 'close' points do not contribute to the
- * sample.  The down-sampling is relied on to correct the error of not using
- * a filter.
- *
- * The line end-caps are 'flat'; they go through the points.  The square line
- * joins are mitres; the outside of the lines are continued to the point of
- * intersection.
- */
-#include <stddef.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <math.h>
-
-/* Normally use <png.h> here to get the installed libpng, but this is done to
- * ensure the code picks up the local libpng implementation:
- */
-#include "../../png.h"
-
-static const struct color
-{
-   const char *name;
-   double      red;
-   double      green;
-   double      blue;
-} colors[] =
-/* color ::= black|white|red|green|yellow|blue
- * color ::= brown|purple|pink|orange|gray|cyan
- */
-{
-   { "black",   0,    0,  0 },
-   { "white",   1,    1,  1 },
-   { "red",     1,    0,  0 },
-   { "green",   0,    1,  0 },
-   { "yellow",  1,    1,  0 },
-   { "blue",    0,    0,  1 },
-   { "brown",  .5, .125,  0 },
-   { "purple",  1,    0,  1 },
-   { "pink",    1,   .5, .5 },
-   { "orange",  1,   .5,  0 },
-   { "gray",    0,   .5, .5 },
-   { "cyan",    0,    1,  1 }
-};
-#define color_count ((sizeof colors)/(sizeof colors[0]))
-
-static const struct color *
-color_of(const char *arg)
-{
-   int icolor = color_count;
-
-   while (--icolor >= 0)
-   {
-      if (strcmp(colors[icolor].name, arg) == 0)
-         return colors+icolor;
-   }
-
-   fprintf(stderr, "genpng: invalid color %s\n", arg);
-   exit(1);
-}
-
-static double
-width_of(const char *arg)
-{
-   if (strcmp(arg, "filled") == 0)
-      return 0;
-
-   else
-   {
-      char *ep = NULL;
-      double w = strtod(arg, &ep);
-
-      if (ep != NULL && *ep == 0 && w > 0)
-         return w;
-   }
-
-   fprintf(stderr, "genpng: invalid line width %s\n", arg);
-   exit(1);
-}
-
-static double
-coordinate_of(const char *arg)
-{
-   char *ep = NULL;
-   double w = strtod(arg, &ep);
-
-   if (ep != NULL && *ep == 0)
-      return w;
-
-   fprintf(stderr, "genpng: invalid coordinate value %s\n", arg);
-   exit(1);
-}
-
-struct arg; /* forward declaration */
-
-typedef int (*shape_fn_ptr)(const struct arg *arg, double x, double y);
-   /* A function to determine if (x,y) is inside the shape.
-    *
-    * There are two implementations:
-    *
-    *    inside_fn: returns true if the point is inside
-    *    check_fn:  returns;
-    *       -1: the point is outside the shape by more than the filter width (2)
-    *        0: the point may be inside the shape
-    *       +1: the point is inside the shape by more than the filter width
-    */
-#define OUTSIDE (-1)
-#define INSIDE  (1)
-
-struct arg
-{
-   const struct color *color;
-   shape_fn_ptr        inside_fn;
-   shape_fn_ptr        check_fn;
-   double              width; /* line width, 0 for 'filled' */
-   double              x1, y1, x2, y2;
-};
-
-/* IMPLEMENTATION NOTE:
- *
- * We want the contribution of each shape to the sample corresponding to each
- * pixel.  This could be obtained by super sampling the image to infinite
- * dimensions, finding each point within the shape and assigning that a value
- * '1' while leaving every point outside the shape with value '0' then
- * downsampling to the image size with sinc; computationally very expensive.
- *
- * Approximations are as follows:
- *
- * 1) If the pixel coordinate is within the shape assume the sample has the
- *    shape color and is opaque, else assume there is no contribution from
- *    the shape.
- *
- *    This is the equivalent of aliased rendering or resampling an image with
- *    a block filter.  The maximum error in the calculated alpha (which will
- *    always be 0 or 1) is 0.5.
- *
- * 2) If the shape is within a square of size 1x1 centered on the pixel assume
- *    that the shape obscures an amount of the pixel equal to its area within
- *    that square.
- *
- *    This is the equivalent of 'pixel coverage' alpha calculation or resampling
- *    an image with a bi-linear filter.  The maximum error is over 0.2, but the
- *    results are often acceptable.
- *
- *    This can be approximated by applying (1) to a super-sampled image then
- *    downsampling with a bi-linear filter.  The error in the super-sampled
- *    image is 0.5 per sample, but the resampling reduces this.
- *
- * 3) Use a better filter with a super-sampled image; in the limit this is the
- *    sinc() approach.
- *
- * 4) Do the geometric calculation; a bivariate definite integral across the
- *    shape, unfortunately this means evaluating Si(x), the integral of sinc(x),
- *    which is still a lot of math.
- *
- * This code uses approach (3) with a bi-cubic filter and 8x super-sampling
- * and method (1) for the super-samples.  This means that the sample is either
- * 0 or 1, depending on whether the sub-pixel is within or outside the shape.
- * The bi-cubic weights are also fixed and the 16 required weights are
- * pre-computed here (note that the 'scale' setting will need to be changed if
- * 'super' is increased).
- *
- * The code also calculates a sum to the edge of the filter. This is not
- * currently used by could be used to optimize the calculation.
- */
-#if 0 /* bc code */
-scale=10
-super=8
-define bicubic(x) {
-   if (x <= 1) return (1.5*x - 2.5)*x*x + 1;
-   if (x <  2) return (((2.5 - 0.5*x)*x - 4)*x + 2);
-   return 0;
-}
-define sum(x) {
-   auto s;
-   s = 0;
-   while (x < 2*super) {
-      s = s + bicubic(x/super);
-      x = x + 1;
-   }
-   return s;
-}
-define results(x) {
-   auto b, s;
-   b = bicubic(x/super);
-   s = sum(x);
-
-   print "   /*", x, "*/ { ", b, ", ", s, " }";
-   return 1;
-}
-x=0
-while (x<2*super) {
-   x = x + results(x)
-   if (x < 2*super) print ","
-   print "\n"
-}
-quit
-#endif
-
-#define BICUBIC1(x) /*     |x| <= 1 */ ((1.5*(x)* - 2.5)*(x)*(x) + 1)
-#define BICUBIC2(x) /* 1 < |x| <  2 */ (((2.5 - 0.5*(x))*(x) - 4)*(x) + 2)
-#define FILTER_WEIGHT 9 /* Twice the first sum below */
-#define FILTER_WIDTH  2 /* Actually half the width; -2..+2 */
-#define FILTER_STEPS  8 /* steps per filter unit */
-static const double
-bicubic[16][2] =
-{
-   /* These numbers are exact; the weight for the filter is 1/9, but this
-    * would make the numbers inexact, so it is not included here.
-    */
-   /*          bicubic      sum        */
-   /* 0*/ { 1.0000000000, 4.5000000000 },
-   /* 1*/ {  .9638671875, 3.5000000000 },
-   /* 2*/ {  .8671875000, 2.5361328125 },
-   /* 3*/ {  .7275390625, 1.6689453125 },
-   /* 4*/ {  .5625000000,  .9414062500 },
-   /* 5*/ {  .3896484375,  .3789062500 },
-   /* 6*/ {  .2265625000, -.0107421875 },
-   /* 7*/ {  .0908203125, -.2373046875 },
-   /* 8*/ {            0, -.3281250000 },
-   /* 9*/ { -.0478515625, -.3281250000 },
-   /*10*/ { -.0703125000, -.2802734375 },
-   /*11*/ { -.0732421875, -.2099609375 },
-   /*12*/ { -.0625000000, -.1367187500 },
-   /*13*/ { -.0439453125, -.0742187500 },
-   /*14*/ { -.0234375000, -.0302734375 },
-   /*15*/ { -.0068359375, -.0068359375 }
-};
-
-static double
-alpha_calc(const struct arg *arg, double x, double y)
-{
-   /* For [x-2..x+2],[y-2,y+2] calculate the weighted bicubic given a function
-    * which tells us whether a point is inside or outside the shape.  First
-    * check if we need to do this at all:
-    */
-   switch (arg->check_fn(arg, x, y))
-   {
-      case OUTSIDE:
-         return 0; /* all samples outside the shape */
-
-      case INSIDE:
-         return 1; /* all samples inside the shape */
-
-      default:
-      {
-         int dy;
-         double alpha = 0;
-
-#        define FILTER_D (FILTER_WIDTH*FILTER_STEPS-1)
-         for (dy=-FILTER_D; dy<=FILTER_D; ++dy)
-         {
-            double wy = bicubic[abs(dy)][0];
-
-            if (wy != 0)
-            {
-               double alphay = 0;
-               int dx;
-
-               for (dx=-FILTER_D; dx<=FILTER_D; ++dx)
-               {
-                  double wx = bicubic[abs(dx)][0];
-
-                  if (wx != 0 && arg->inside_fn(arg, x+dx/16, y+dy/16)) 
-                     alphay += wx;
-               }
-
-               alpha += wy * alphay;
-            }
-         }
-
-         /* This needs to be weighted for each dimension: */
-         return alpha / (FILTER_WEIGHT*FILTER_WEIGHT);
-      }
-   }
-}
-
-/* These are the shape functions. */
-/* "square",
- * { inside_square_filled, check_square_filled },
- * { inside_square, check_square }
- */
-static int
-square_check(double x, double y, double x1, double y1, double x2, double y2)
-   /* Is x,y inside the square (x1,y1)..(x2,y2)? */
-{
-   /* Do a modified Cohen-Sutherland on one point, bit patterns that indicate
-    * 'outside' are:
-    *
-    *   x<x1 | x<y1 | x<x2 | x<y2
-    *    0      x      0      x     To the right
-    *    1      x      1      x     To the left
-    *    x      0      x      0     Below
-    *    x      1      x      1     Above
-    *
-    * So 'inside' is (x<x1) != (x<x2) && (y<y1) != (y<y2);
-    */
-   return ((x<x1) ^ (x<x2)) & ((y<y1) ^ (y<y2));
-}
-
-static int
-inside_square_filled(const struct arg *arg, double x, double y)
-{
-   return square_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2);
-}
-
-static int
-square_check_line(const struct arg *arg, double x, double y, double w)
-   /* Check for a point being inside the boundaries implied by the given arg
-    * and assuming a width 2*w each side of the boundaries.  This returns the
-    * 'check' INSIDE/OUTSIDE/0 result but note the semantics:
-    *
-    *          +--------------+
-    *          |              |   OUTSIDE
-    *          |   INSIDE     |
-    *          |              |
-    *          +--------------+
-    *
-    * And '0' means within the line boundaries.
-    */
-{
-   double cx = (arg->x1+arg->x2)/2;
-   double wx = fabs(arg->x1-arg->x2)/2;
-   double cy = (arg->y1+arg->y2)/2;
-   double wy = fabs(arg->y1-arg->y2)/2;
-
-   if (square_check(x, y, cx-wx-w, cy-wy-w, cx+wx+w, cy+wy+w))
-   {
-      /* Inside, but maybe too far; check for the redundant case where
-       * the lines overlap:
-       */
-      wx -= w;
-      wy -= w;
-      if (wx > 0 && wy > 0 && square_check(x, y, cx-wx, cy-wy, cx+wx, cy+wy))
-         return INSIDE; /* between (inside) the boundary lines. */
-
-      return 0; /* inside the lines themselves. */
-   }
-
-   return OUTSIDE; /* outside the boundary lines. */
-}
-
-static int
-check_square_filled(const struct arg *arg, double x, double y)
-{
-   /* The filter extends +/-FILTER_WIDTH each side of each output point, so
-    * the check has to expand and contract the square by that amount; '0'
-    * means close enough to the edge of the square that the bicubic filter has
-    * to be run, OUTSIDE means alpha==0, INSIDE means alpha==1.
-    */
-   return square_check_line(arg, x, y, FILTER_WIDTH);
-}
-
-static int
-inside_square(const struct arg *arg, double x, double y)
-{
-   /* Return true if within the drawn lines, else false, no need to distinguish
-    * INSIDE vs OUTSIDE here:
-    */
-   return square_check_line(arg, x, y, arg->width/2) == 0;
-}
-
-static int
-check_square(const struct arg *arg, double x, double y)
-{
-   /* So for this function a result of 'INSIDE' means inside the actual lines.
-    */
-   double w = arg->width/2;
-
-   if (square_check_line(arg, x, y, w+FILTER_WIDTH) == 0)
-   {
-      /* Somewhere close to the boundary lines. If far enough inside one of
-       * them then we can return INSIDE:
-       */
-      w -= FILTER_WIDTH;
-
-      if (w > 0 && square_check_line(arg, x, y, w) == 0)
-         return INSIDE;
-
-      /* Point is somewhere in the filter region: */
-      return 0;
-   }
-
-   else /* Inside or outside the square by more than w+FILTER_WIDTH. */
-      return OUTSIDE;
-}
-
-/* "circle",
- * { inside_circle_filled, check_circle_filled },
- * { inside_circle, check_circle }
- *
- * The functions here are analoguous to the square ones; however, they check
- * the corresponding ellipse as opposed to the rectangle.
- */
-static int
-circle_check(double x, double y, double x1, double y1, double x2, double y2)
-{
-   if (square_check(x, y, x1, y1, x2, y2))
-   {
-      /* Inside the square, so maybe inside the circle too: */
-      const double cx = (x1 + x2)/2;
-      const double cy = (y1 + y2)/2;
-      const double dx = x1 - x2;
-      const double dy = y1 - y2;
-
-      x = (x - cx)/dx;
-      y = (y - cy)/dy;
-
-      /* It is outside if the distance from the center is more than half the
-       * diameter:
-       */
-      return x*x+y*y < .25;
-   }
-
-   return 0; /* outside */
-}
-
-static int
-inside_circle_filled(const struct arg *arg, double x, double y)
-{
-   return circle_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2);
-}
-
-static int
-circle_check_line(const struct arg *arg, double x, double y, double w)
-   /* Check for a point being inside the boundaries implied by the given arg
-    * and assuming a width 2*w each side of the boundaries.  This function has
-    * the same semantic as square_check_line but tests the circle.
-    */
-{
-   double cx = (arg->x1+arg->x2)/2;
-   double wx = fabs(arg->x1-arg->x2)/2;
-   double cy = (arg->y1+arg->y2)/2;
-   double wy = fabs(arg->y1-arg->y2)/2;
-
-   if (circle_check(x, y, cx-wx-w, cy-wy-w, cx+wx+w, cy+wy+w))
-   {
-      /* Inside, but maybe too far; check for the redundant case where
-       * the lines overlap:
-       */
-      wx -= w;
-      wy -= w;
-      if (wx > 0 && wy > 0 && circle_check(x, y, cx-wx, cy-wy, cx+wx, cy+wy))
-         return INSIDE; /* between (inside) the boundary lines. */
-
-      return 0; /* inside the lines themselves. */
-   }
-
-   return OUTSIDE; /* outside the boundary lines. */
-}
-
-static int
-check_circle_filled(const struct arg *arg, double x, double y)
-{
-   return circle_check_line(arg, x, y, FILTER_WIDTH);
-}
-
-static int
-inside_circle(const struct arg *arg, double x, double y)
-{
-   return circle_check_line(arg, x, y, arg->width/2) == 0;
-}
-
-static int
-check_circle(const struct arg *arg, double x, double y)
-{
-   /* Exactly as the 'square' code.  */
-   double w = arg->width/2;
-
-   if (circle_check_line(arg, x, y, w+FILTER_WIDTH) == 0)
-   {
-      w -= FILTER_WIDTH;
-
-      if (w > 0 && circle_check_line(arg, x, y, w) == 0)
-         return INSIDE;
-
-      /* Point is somewhere in the filter region: */
-      return 0;
-   }
-
-   else /* Inside or outside the square by more than w+FILTER_WIDTH. */
-      return OUTSIDE;
-}
-
-/* "line",
- * { NULL, NULL },  There is no 'filled' line.
- * { inside_line, check_line }
- */
-static int
-line_check(double x, double y, double x1, double y1, double x2, double y2,
-   double w, double expand)
-{
-   /* Shift all the points to (arg->x1, arg->y1) */
-   double lx = x2 - x1;
-   double ly = y2 - y1;
-   double len2 = lx*lx + ly*ly;
-   double cross, dot;
-
-   x -= x1;
-   y -= y1;
-
-   /* The dot product is the distance down the line, the cross product is
-    * the distance away from the line:
-    *
-    *    distance = |cross| / sqrt(len2) 
-    */
-   cross = x * ly - y * lx;
-
-   /* If 'distance' is more than w the point is definitely outside the line:
-    *
-    *     distance >= w
-    *     |cross|  >= w * sqrt(len2)
-    *     cross^2  >= w^2 * len2:
-    */
-   if (cross*cross >= (w+expand)*(w+expand)*len2)
-      return 0; /* outside */
-
-   /* Now find the distance *along* the line; this comes from the dot product
-    * lx.x+ly.y. The actual distance (in pixels) is:
-    *
-    *   distance = dot / sqrt(len2)
-    */
-   dot = lx * x + ly * y;
-
-   /* The test for 'outside' is:
-    *
-    *    distance < 0 || distance > sqrt(len2)
-    *                 -> dot / sqrt(len2) > sqrt(len2)
-    *                 -> dot > len2
-    *
-    * But 'expand' is used for the filter width and needs to be handled too:
-    */
-   return dot > -expand && dot < len2+expand;
-}
-
-static int
-inside_line(const struct arg *arg, double x, double y)
-{
-   return line_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2, arg->width/2, 0);
-}
-
-static int
-check_line(const struct arg *arg, double x, double y)
-{
-   /* The end caps of the line must be checked too; it's not enough just to
-    * widen the line by FILTER_WIDTH; 'expand' exists for this purpose:
-    */
-   if (line_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2, arg->width/2,
-       FILTER_WIDTH))
-   {
-      /* Inside the line+filter; far enough inside that the filter isn't
-       * required?
-       */
-      if (arg->width > 2*FILTER_WIDTH &&
-          line_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2, arg->width/2,
-             -FILTER_WIDTH))
-         return INSIDE;
-
-      return 0;
-   }
-
-   return OUTSIDE;
-}
-
-static const struct
-{
-   const char    *name;
-   shape_fn_ptr   function[2/*fill,line*/][2];
-#  define         FN_INSIDE 0
-#  define         FN_CHECK 1
-} shape_defs[] =
-{
-   {  "square",
-      {  { inside_square_filled, check_square_filled },
-         { inside_square, check_square } }
-   },
-   {  "circle",
-      {  { inside_circle_filled, check_circle_filled },
-         { inside_circle, check_circle } }
-   },
-   {  "line",
-      {  { NULL, NULL },
-         { inside_line, check_line } }
-   }
-};
-
-#define shape_count ((sizeof shape_defs)/(sizeof shape_defs[0]))
-
-static shape_fn_ptr
-shape_of(const char *arg, double width, int f)
-{
-   unsigned int i;
-
-   for (i=0; i<shape_count; ++i) if (strcmp(shape_defs[i].name, arg) == 0)
-   {
-      shape_fn_ptr fn = shape_defs[i].function[width != 0][f];
-
-      if (fn != NULL)
-         return fn;
-
-      fprintf(stderr, "genpng: %s %s not supported\n",
-         width == 0 ? "filled" : "unfilled", arg);
-      exit(1);
-   }
-
-   fprintf(stderr, "genpng: %s: not a valid shape name\n", arg);
-   exit(1);
-}
-
-static void
-parse_arg(struct arg *arg, const char **argv/*7 arguments*/)
-{
-   /* shape ::= color width shape x1 y1 x2 y2 */
-   arg->color = color_of(argv[0]);
-   arg->width = width_of(argv[1]);
-   arg->inside_fn = shape_of(argv[2], arg->width, FN_INSIDE);
-   arg->check_fn = shape_of(argv[2], arg->width, FN_CHECK);
-   arg->x1 = coordinate_of(argv[3]);
-   arg->y1 = coordinate_of(argv[4]);
-   arg->x2 = coordinate_of(argv[5]);
-   arg->y2 = coordinate_of(argv[6]);
-}
-
-static png_uint_32
-read_wh(const char *name, const char *str)
-   /* read a PNG width or height */
-{
-   char *ep = NULL;
-   unsigned long ul = strtoul(str, &ep, 10);
-
-   if (ep != NULL && *ep == 0 && ul > 0 && ul <= 0x7fffffff)
-      return (png_uint_32)/*SAFE*/ul;
-
-   fprintf(stderr, "genpng: %s: invalid number %s\n", name, str);
-   exit(1);
-}
-
-static void
-pixel(png_uint_16p p, struct arg *args, int nargs, double x, double y)
-{
-   /* Fill in the pixel by checking each shape (args[nargs]) for effects on
-    * the corresponding sample:
-    */
-   double r=0, g=0, b=0, a=0;
-
-   while (--nargs >= 0 && a != 1)
-   {
-      /* NOTE: alpha_calc can return a value outside the range 0..1 with the
-       * bicubic filter.
-       */
-      const double alpha = alpha_calc(args+nargs, x, y) * (1-a);
-
-      r += alpha * args[nargs].color->red;
-      g += alpha * args[nargs].color->green;
-      b += alpha * args[nargs].color->blue;
-      a += alpha;
-   }
-
-   /* 'a' may be negative or greater than 1; if it is, negative clamp the
-    * pixel to 0 if >1 clamp r/g/b:
-    */
-   if (a > 0) 
-   {
-      if (a > 1)
-      {
-         if (r > 1) r = 1;
-         if (g > 1) g = 1;
-         if (b > 1) b = 1;
-         a = 1;
-      }
-
-      /* And fill in the pixel: */
-      p[0] = (png_uint_16)/*SAFE*/round(r * 65535);
-      p[1] = (png_uint_16)/*SAFE*/round(g * 65535);
-      p[2] = (png_uint_16)/*SAFE*/round(b * 65535);
-      p[3] = (png_uint_16)/*SAFE*/round(a * 65535);
-   }
-
-   else
-      p[3] = p[2] = p[1] = p[0] = 0;
-}
-
-int
-main(int argc, const char **argv)
-{
-   int convert_to_8bit = 0;
-
-   /* There is one option: --8bit: */
-   if (argc > 1 && strcmp(argv[1], "--8bit") == 0)
-      --argc, ++argv, convert_to_8bit = 1;
-
-   if (argc >= 3)
-   {
-      png_uint_16p buffer;
-      int nshapes;
-      png_image image;
-#     define max_shapes 256
-      struct arg arg_list[max_shapes];
-
-      /* The libpng Simplified API write code requires a fully initialized
-       * structure.
-       */
-      memset(&image, 0, sizeof image);
-      image.version = PNG_IMAGE_VERSION;
-      image.opaque = NULL;
-      image.width = read_wh("width", argv[1]);
-      image.height = read_wh("height", argv[2]);
-      image.format = PNG_FORMAT_LINEAR_RGB_ALPHA;
-      image.flags = 0;
-      image.colormap_entries = 0;
-
-      /* Check the remainder of the arguments */
-      for (nshapes=0; 3+7*(nshapes+1) <= argc && nshapes < max_shapes;
-           ++nshapes)
-         parse_arg(arg_list+nshapes, argv+3+7*nshapes);
-
-      if (3+7*nshapes != argc)
-      {
-         fprintf(stderr, "genpng: %s: too many arguments\n", argv[3+7*nshapes]);
-         return 1;
-      }
-
-      /* Create the buffer: */
-      buffer = malloc(PNG_IMAGE_SIZE(image));
-
-      if (buffer != NULL)
-      {
-         png_uint_32 y;
-
-         /* Write each row... */
-         for (y=0; y<image.height; ++y)
-         {
-            png_uint_32 x;
-
-            /* Each pixel in each row: */
-            for (x=0; x<image.width; ++x)
-               pixel(buffer + 4*(x + y*image.width), arg_list, nshapes, x, y);
-         }
-
-         /* Write the result (to stdout) */
-         if (png_image_write_to_stdio(&image, stdout, convert_to_8bit,
-             buffer, 0/*row_stride*/, NULL/*colormap*/))
-         {
-            free(buffer);
-            return 0; /* success */
-         }
-
-         else
-            fprintf(stderr, "genpng: write stdout: %s\n", image.message);
-
-         free(buffer);
-      }
-
-      else
-         fprintf(stderr, "genpng: out of memory: %lu bytes\n",
-               (unsigned long)PNG_IMAGE_SIZE(image));
-   }
-
-   else
-   {
-      /* Wrong number of arguments */
-      fprintf(stderr, "genpng: usage: genpng [--8bit] width height {shape}\n"
-         " Generate a transparent PNG in RGBA (truecolor+alpha) format\n"
-         " containing the given shape or shapes.  Shapes are defined:\n"
-         "\n"
-         "  shape ::= color width shape x1 y1 x2 y2\n"
-         "  color ::= black|white|red|green|yellow|blue\n"
-         "  color ::= brown|purple|pink|orange|gray|cyan\n"
-         "  width ::= filled|<number>\n"
-         "  shape ::= circle|square|line\n"
-         "  x1,x2 ::= <number>\n"
-         "  y1,y2 ::= <number>\n"
-         "\n"
-         " Numbers are floating point numbers describing points relative to\n"
-         " the top left of the output PNG as pixel coordinates.  The 'width'\n"
-         " parameter is either the width of the line (in output pixels) used\n"
-         " to draw the shape or 'filled' to indicate that the shape should\n"
-         " be filled with the color.\n"
-         "\n"
-         " Colors are interpreted loosely to give access to the eight full\n"
-         " intensity RGB values:\n"
-         "\n"
-         "  black, red, green, blue, yellow, cyan, purple, white,\n"
-         "\n"
-         " Cyan is full intensity blue+green; RGB(0,1,1), plus the following\n"
-         " lower intensity values:\n"
-         "\n"
-         "  brown:  red+orange:  RGB(0.5, 0.125, 0) (dark red+orange)\n"
-         "  pink:   red+white:   RGB(1.0, 0.5,   0.5)\n"
-         "  orange: red+yellow:  RGB(1.0, 0.5,   0)\n"
-         "  gray:   black+white: RGB(0.5, 0.5,   0.5)\n"
-         "\n"
-         " The RGB values are selected to make detection of aliasing errors\n"
-         " easy. The names are selected to make the description of errors\n"
-         " easy.\n"
-         "\n"
-         " The PNG is written to stdout, if --8bit is given a 32bpp RGBA sRGB\n"
-         " file is produced, otherwise a 64bpp RGBA linear encoded file is\n"
-         " written.\n");
-   }
-
-   return 1;
-}
--- a/contrib/tools/pngfix.c
+++ b/contrib/tools/pngfix.c
@@ -2,7 +2,7 @@
 *
 * Copyright (c) 2014-2015 John Cunningham Bowler
 *
- * Last changed in libpng 1.6.17 [(PENDING RELEASE)]
+ * Last changed in libpng 1.6.17 [March 26, 2015]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng

- libpng version 1.6.18beta03 - May 6, 2015
+ libpng version 1.6.17 - March 26, 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 1.6.18beta03 - May 6, 2015
+ libpng versions 0.97, January 1998, through 1.6.17 - March 26, 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

-May 6, 2015
+March 26, 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 1.6.18beta03 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.17 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
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "May 6, 2015"
+.TH LIBPNG 3 "March 26, 2015"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.18beta03
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.17
 .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 1.6.18beta03 - May 6, 2015
+ libpng version 1.6.17 - March 26, 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 1.6.18beta03 - May 6, 2015
+ libpng versions 0.97, January 1998, through 1.6.17 - March 26, 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

-May 6, 2015
+March 26, 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 1.6.18beta03 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.17 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
@@ -6044,7 +6044,6 @@ the first widely used release:
 1.6.17beta01-06     16    10617  16.so.16.17[.0]
 1.6.17rc01-06       16    10617  16.so.16.17[.0]
 1.6.17              16    10617  16.so.16.17[.0]
- 1.6.18beta01-03     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
@@ -6101,7 +6100,7 @@ possible without all of you.

 Thanks to Frank J. T. Wojcik for helping with the documentation.

-Libpng version 1.6.18beta03 - May 6, 2015:
+Libpng version 1.6.17 - March 26, 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).

@@ -6124,7 +6123,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.2.6, August 15, 2004, through 1.6.18beta03, May 6, 2015, are
+libpng versions 1.2.6, August 15, 2004, through 1.6.17, March 26, 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
@@ -6223,7 +6222,7 @@ certification mark of the Open Source Initiative.

 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 6, 2015
+March 26, 2015

 .\" end of man page

--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "May 6, 2015"
+.TH LIBPNGPF 3 "March 26, 2015"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.18beta03
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.17
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "May 6, 2015"
+.TH PNG 5 "March 26, 2015"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@

 /* png.c - location for general purpose libpng functions
 *
- * Last changed in libpng 1.6.18 [(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_18beta03 Your_png_h_is_not_version_1_6_18beta03;
+typedef png_libpng_version_1_6_17 Your_png_h_is_not_version_1_6_17;

 /* 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 1.6.18beta03 - May 6, 2015" PNG_STRING_NEWLINE \
+     "libpng version 1.6.17 - March 26, 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 1.6.18beta03 - May 6, 2015\
+      return "libpng version 1.6.17 - March 26, 2015\
      Copyright (c) 1998-2015 Glenn Randers-Pehrson\
      Copyright (c) 1996-1997 Andreas Dilger\
      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -2276,7 +2276,7 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,

         /* Length *and* intent must match */
         if (length == png_sRGB_checks[i].length &&
-            intent == (png_uint_32) png_sRGB_checks[i].intent)
+            intent == png_sRGB_checks[i].intent)
         {
            /* Now calculate the adler32 if not done already. */
            if (adler == 0)
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@

 /* png.h - header file for PNG reference library
 *
- * libpng version 1.6.18beta03, May 6, 2015
+ * libpng version 1.6.17, March 26, 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 1.6.18beta03, May 6, 2015: Glenn
+ *   libpng versions 0.97, January 1998, through 1.6.17, March 26, 2015: Glenn
 *   See also "Contributing Authors", below.
 *
 * Note about libpng version numbers:
@@ -216,7 +216,6 @@
 *    1.6.17beta01-06         16    10617  16.so.16.17[.0]
 *    1.6.17rc01-06           16    10617  16.so.16.17[.0]
 *    1.6.17                  16    10617  16.so.16.17[.0]
- *    1.6.18beta01-03         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
@@ -248,7 +247,7 @@
 *
 * This code is released under the libpng license.
 *
- * libpng versions 1.2.6, August 15, 2004, through 1.6.18beta03, May 6, 2015, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.6.17, March 26, 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:
@@ -360,13 +359,13 @@
 * Y2K compliance in libpng:
 * =========================
 *
- *    May 6, 2015
+ *    March 26, 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 1.6.18beta03 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.17 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
@@ -428,9 +427,9 @@
 */

 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.18beta03"
+#define PNG_LIBPNG_VER_STRING "1.6.17"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.18beta03 - May 6, 2015\n"
+     " libpng version 1.6.17 - March 26, 2015\n"

 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -438,13 +437,13 @@
 /* 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 18
+#define PNG_LIBPNG_VER_RELEASE 17

 /* This should match the numeric part of the final component of
 * PNG_LIBPNG_VER_STRING, omitting any leading zero:
 */

-#define PNG_LIBPNG_VER_BUILD  03
+#define PNG_LIBPNG_VER_BUILD  0

 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
@@ -461,7 +460,7 @@
 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
                                       PNG_LIBPNG_BUILD_PRIVATE */

-#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_BETA
+#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE

 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
 * We must not include leading zeros.
@@ -469,7 +468,7 @@
 * version 1.0.0 was mis-numbered 100 instead of 10000).  From
 * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
 */
-#define PNG_LIBPNG_VER 10618 /* 1.6.18 */
+#define PNG_LIBPNG_VER 10617 /* 1.6.17 */

 /* Library configuration: these options cannot be changed after
 * the library has been built.
@@ -574,7 +573,7 @@ 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_18beta03;
+typedef char* png_libpng_version_1_6_17;

 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 *
@@ -2784,9 +2783,8 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
 *
 * To read a PNG file using the simplified API:
 *
- * 1) Declare a 'png_image' structure (see below) on the stack, set the
- *    version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
- *    (this is REQUIRED, your program may crash if you don't do it.)
+ * 1) Declare a 'png_image' structure (see below) on the stack and set the
+ *    version field to PNG_IMAGE_VERSION.
 * 2) Call the appropriate png_image_begin_read... function.
 * 3) Set the png_image 'format' member to the required sample format.
 * 4) Allocate a buffer for the image and, if required, the color-map.
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@

 /* pngconf.h - machine configurable file for libpng
 *
- * libpng version 1.6.18beta03, (PENDING RELEASE)
+ * libpng version 1.6.17, March 26, 2015
 *
 * Copyright (c) 1998-2015 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
--- a/pngmem.c
+++ b/pngmem.c
@@ -77,9 +77,6 @@ png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
   PNG_UNUSED(png_ptr)
 #endif

-   /* Some compilers complain that this is always true.  However, it
-    * can be false when integer overflow happens.
-    */
   if (size > 0 && size <= PNG_SIZE_MAX
 #     ifdef PNG_MAX_MALLOC_64K
         && size <= 65536U
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,7 +1,7 @@

 /* pngpread.c - read a png file in push mode
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -584,11 +584,13 @@ png_push_save_buffer(png_structrp png_ptr)
      if (png_ptr->save_buffer == NULL)
      {
         png_free(png_ptr, old_buffer);
+         old_buffer = NULL;
         png_error(png_ptr, "Insufficient memory for save_buffer");
      }

      memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
      png_free(png_ptr, old_buffer);
+      old_buffer = NULL;
      png_ptr->save_buffer_max = new_max;
   }
   if (png_ptr->current_buffer_size)
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1,7 +1,7 @@

 /* pngpriv.h - private declarations for use inside libpng
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -118,12 +118,8 @@
    * to compile with an appropriate #error if ALIGNED_MEMORY has been turned
    * off.
    *
-    * Note that gcc-4.9 defines __ARM_NEON instead of the deprecated
-    * __ARM_NEON__, so we check both variants.
-    *
-    * To disable ARM_NEON optimizations entirely, and skip compiling the
-    * associated assembler code, pass --enable-arm-neon=no to configure
-    * or put -DPNG_ARM_NEON_OPT=0 in CPPFLAGS.
+    * Note that gcc-4.9 defines __ARM_NEON instead of __ARM_NEON__, so we
+    * check both variants.
    */
 #  if (defined(__ARM_NEON__) || defined(__ARM_NEON)) && \
   defined(PNG_ALIGNED_MEMORY_SUPPORTED)
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1,7 +1,7 @@

 /* pngrtran.c - transforms the data in a row for PNG readers
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -4460,7 +4460,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,

               for (i = 0; i < row_width; i++)
               {
-                  if ((*sp & 0xff) == gray)
+                  if (*sp == gray)
                     *dp-- = 0;

                  else
@@ -4478,8 +4478,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
               dp = row + (row_info->rowbytes << 1) - 1;
               for (i = 0; i < row_width; i++)
               {
-                  if ((*(sp - 1) & 0xff) == gray_high &&
-                      (*(sp) & 0xff) == gray_low)
+                  if (*(sp - 1) == gray_high && *(sp) == gray_low)
                  {
                     *dp-- = 0;
                     *dp-- = 0;
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@

 /* pngrutil.c - utilities to read a PNG file
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -575,7 +575,7 @@ png_decompress_chunk(png_structrp png_ptr,
    */
   png_alloc_size_t limit = PNG_SIZE_MAX;

-# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+# ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
   if (png_ptr->user_chunk_malloc_max > 0 &&
       png_ptr->user_chunk_malloc_max < limit)
      limit = png_ptr->user_chunk_malloc_max;
@@ -670,6 +670,7 @@ png_decompress_chunk(png_structrp png_ptr,
                   * success)
                   */
                  png_free(png_ptr, text);
+                  text = NULL;

                  /* This really is very benign, but it's still an error because
                   * the extra space may otherwise be used as a Trojan Horse.
@@ -1816,8 +1817,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
         return;
      }

-      if (length > png_ptr->num_palette ||
-         length > (unsigned int) PNG_MAX_PALETTE_LENGTH ||
+      if (length > png_ptr->num_palette || length > PNG_MAX_PALETTE_LENGTH ||
         length == 0)
      {
         png_crc_finish(png_ptr, length);
@@ -1980,7 +1980,7 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   num = length / 2 ;

-   if (num != png_ptr->num_palette || num > (unsigned int) PNG_MAX_PALETTE_LENGTH)
+   if (num != png_ptr->num_palette || num > PNG_MAX_PALETTE_LENGTH)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "invalid");
@@ -2715,7 +2715,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
      png_ptr->unknown_chunk.data = NULL;
   }

-#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
+#  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
      if (png_ptr->user_chunk_malloc_max > 0 &&
          png_ptr->user_chunk_malloc_max < limit)
         limit = png_ptr->user_chunk_malloc_max;
--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@

 /* pngset.c - storage of image information into info struct
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -673,6 +673,7 @@ png_set_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
   if (new_iccp_profile == NULL)
   {
      png_free(png_ptr, new_iccp_name);
+      new_iccp_name = NULL;
      png_benign_error(png_ptr,
          "Insufficient memory to process iCCP profile");

@@ -709,7 +710,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   int i;

-   png_debug1(1, "in %lx storage function", png_ptr == NULL ? 0xabadca11 :
+   png_debug1(1, "in %lx storage function", png_ptr == NULL ? "unexpected" :
      (unsigned long)png_ptr->chunk_name);

   if (png_ptr == NULL || info_ptr == NULL || num_text <= 0 || text_ptr == NULL)
@@ -1521,9 +1522,6 @@ png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
         }

 #ifndef __COVERITY__
-         /* Some compilers complain that this is always false.  However, it
-          * can be true when integer overflow happens.
-          */
         if (size > ZLIB_IO_MAX)
         {
            png_warning(png_ptr,
--- a/pngtest.c
+++ b/pngtest.c
@@ -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_18beta03 Your_png_h_is_not_version_1_6_18beta03;
+typedef png_libpng_version_1_6_17 Your_png_h_is_not_version_1_6_17;
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -1,7 +1,7 @@

 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -704,7 +704,7 @@ png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
             */
            for (; rp > png_ptr->row_buf; rp--)
            {
-              if ((*rp >> padding) != 0)
+              if (*rp >> padding != 0)
                 png_ptr->num_palette_max = 1;
              padding = 0;
            }
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -216,13 +216,8 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
      if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0 &&
          info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
-         int j, jend;
-
-         jend = info_ptr->num_trans;
-         if (jend > PNG_MAX_PALETTE_LENGTH)
-            jend = PNG_MAX_PALETTE_LENGTH;
-
-         for (j = 0; j<jend; ++j)
+         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]);
      }
--- a/pngwtran.c
+++ b/pngwtran.c
@@ -1,7 +1,7 @@

 /* pngwtran.c - transforms the data in a row for PNG writers
 *
- * Last changed in libpng 1.6.18 [(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.)
@@ -422,7 +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++));
+               *(dp++) = (png_byte)(255 - *(sp++));
            }
         }

@@ -446,7 +446,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
               */
               sp+=6; dp = sp;
               *(dp++) = (png_byte)(255 - *(sp++));
-               *dp     = (png_byte)(255 - *(sp++));
+               *(dp++) = (png_byte)(255 - *(sp++));
            }
         }
 #endif /* WRITE_16BIT */
@@ -484,7 +484,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
               */
               sp+=2; dp = sp;
               *(dp++) = (png_byte)(255 - *(sp++));
-               *dp     = (png_byte)(255 - *(sp++));
+               *(dp++) = (png_byte)(255 - *(sp++));
            }
         }
 #endif /* WRITE_16BIT */
--- a/projects/vstudio/readme.txt
+++ b/projects/vstudio/readme.txt
@@ -1,7 +1,7 @@

 VisualStudio instructions

-libpng version 1.6.18beta03 - May 6, 2015
+libpng version 1.6.17 - March 26, 2015

 Copyright (c) 1998-2010 Glenn Randers-Pehrson

--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
 * zlib.props - location of zlib source
 *
- * libpng version 1.6.18beta03 - May 6, 2015
+ * libpng version 1.6.17 - March 26, 2015
 *
 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
 *
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@

-Makefiles for  libpng version 1.6.18beta03 - May 6, 2015
+Makefiles for  libpng version 1.6.17 - March 26, 2015

 pnglibconf.h.prebuilt       =>  Stores configuration settings
 makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.18beta03)
+                       (gcc, creates libpng16.so.16.1.6.17)
 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.16.1.6.18beta03)
+                       creates libpng16.so.16.1.6.17)
 makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
 makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.18beta03)
+                       creates libpng16.so.16.1.6.17)
 makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.18beta03)
+                       creates libpng16.so.16.1.6.17)
 makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
 makefile.sunos    =>  Sun makefile
 makefile.32sunu   =>  Sun Ultra 32-bit makefile
--- a/scripts/def.c
+++ b/scripts/def.c
@@ -21,7 +21,7 @@ PNG_DFN "OS2 DESCRIPTION "PNG image compression library""
 PNG_DFN "OS2 CODE PRELOAD MOVEABLE DISCARDABLE"
 PNG_DFN ""
 PNG_DFN "EXPORTS"
-PNG_DFN ";Version 1.6.18beta03"
+PNG_DFN ";Version 1.6.17"

 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
        PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@

 # Modeled after libxml-config.

-version=1.6.18beta03
+version=1.6.17
 prefix=""
 libdir=""
 libs=""
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@ includedir=@includedir@/libpng16

 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.18beta03
+Version: 1.6.17
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@

 VERMAJ = 1
 VERMIN = 6
-VERMIC = 18
+VERMIC = 17
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 18
+RELEASE = 17

 # Shared library names:
 LIBSO=$(LIBNAME).so
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@ exec_prefix=$(prefix)
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 18
+RELEASE = 17

 # Shared library names:
 LIBSO=$(LIBNAME).dll
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include/libpng16

 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.18beta03
+SHLIB_MINOR=	1.6.17
 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
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include

 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.18beta03
+SHLIB_MINOR=	1.6.17
 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
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@ LIBDIR=	${PREFIX}/lib
 MANDIR= ${PREFIX}/man/cat

 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.18beta03
+SHLIB_MINOR=	1.6.17

 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.18beta03 STANDARD API DEFINITION */
+/* libpng 1.6.17 STANDARD API DEFINITION */

 /* pnglibconf.h - library build configuration */

-/* Libpng version 1.6.18beta03 - May 6, 2015 */
+/* Libpng version 1.6.17 - March 26, 2015 */

 /* Copyright (c) 1998-2014 Glenn Randers-Pehrson */

@@ -101,6 +101,8 @@
 #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
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.18beta03
+;Version 1.6.17
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng