[libpng16] Imported from libpng-1.6.15beta04.tar

[libpng16] Removed new PNG_USE_ARM_NEON configuration flag and made a one-line
revision to configure.ac to support ARM on aarch64 instead (John Bowler).
2025-07-10 18:04:09 +02:00 · 2014-11-04 07:08:23 -06:00 · 2014-11-03 19:44:39 -06:00 · 2014-11-03 09:33:51 -06:00 · 2014-11-03 09:33:44 -06:00 · 2014-11-03 08:24:34 -06:00
38 changed files with 994 additions and 886 deletions
--- a/26
+++ b/26
@@ -1,4 +1,4 @@
-Libpng 1.6.15beta01 - October 29, 2014
+Libpng 1.6.15beta04 - November 4, 2014

 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -8,20 +8,20 @@ Files available for download:
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script

-   1.6.15beta01.tar.xz (LZMA-compressed, recommended)
-   1.6.15beta01.tar.gz
+   1.6.15beta04.tar.xz (LZMA-compressed, recommended)
+   1.6.15beta04.tar.gz

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

-   lp1615b01.7z  (LZMA-compressed, recommended)
-   lp1615b01.zip
+   lp1615b04.7z  (LZMA-compressed, recommended)
+   lp1615b04.zip

 Other information:

-   1.6.15beta01-README.txt
-   1.6.15beta01-LICENSE.txt
-   libpng-1.6.15beta01-*.asc (armored detached GPG signatures)
+   1.6.15beta04-README.txt
+   1.6.15beta04-LICENSE.txt
+   libpng-1.6.15beta04-*.asc (armored detached GPG signatures)

 Changes since the last public release (1.6.14):

@@ -30,6 +30,16 @@ Version 1.6.15beta01 [October 29, 2014]
  Simplified png_free_data().
  Added missing "ptr = NULL" after some instances of png_free().

+Version 1.6.15beta02 [November 1, 2014]
+  Changed remaining "if (!x)" to "if (x == 0)" and "if (x)" to "if (x !== 0)"
+
+Version 1.6.15beta03 [November 3, 2014]
+  Added PNG_USE_ARM_NEON configuration flag (Marcin Juszkiewicz).
+
+Version 1.6.15beta04 [November 4, 2014]
+  Removed new PNG_USE_ARM_NEON configuration flag and made a one-line
+    revision to configure.ac to support ARM on aarch64 instead (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/10
+++ b/10
@@ -5038,6 +5038,16 @@ Version 1.6.15beta01 [October 29, 2014]
  Simplified png_free_data().
  Added missing "ptr = NULL" after some instances of png_free().

+Version 1.6.15beta02 [November 1, 2014]
+  Changed remaining "if (!x)" to "if (x == 0)" and "if (x)" to "if (x !== 0)"
+
+Version 1.6.15beta03 [November 3, 2014]
+  Added PNG_USE_ARM_NEON configuration flag (Marcin Juszkiewicz).
+
+Version 1.6.15beta04 [November 4, 2014]
+  Removed new PNG_USE_ARM_NEON configuration flag and made a one-line
+    revision to configure.ac to support ARM on aarch64 instead (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
@@ -253,7 +253,7 @@ endif(NOT WIN32 OR CYGWIN OR MINGW)
 # SET UP LINKS
 if(PNG_SHARED)
  set_target_properties(${PNG_LIB_NAME} PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.15beta01
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.15beta04
    VERSION 16.${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 1.6.15beta01, October 29, 2014, are
+libpng versions 1.2.6, August 15, 2004, through 1.6.15beta04, November 4, 2014, are
 Copyright (c) 2004, 2006-2014 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
-October 29, 2014
+November 4, 2014
--- a/2
+++ b/2
@@ -1,4 +1,4 @@
-README for libpng version 1.6.15beta01 - October 29, 2014 (shared library 16.0)
+README for libpng version 1.6.15beta04 - November 4, 2014 (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/configure.ac
+++ b/configure.ac
@@ -18,7 +18,7 @@ AC_PREREQ([2.68])

 dnl Version number stuff here:

-AC_INIT([libpng],[1.6.15beta01],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.15beta04],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])

 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -39,7 +39,7 @@ 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=1.6.15beta01
+PNGLIB_VERSION=1.6.15beta04
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
 PNGLIB_RELEASE=15
@@ -310,7 +310,7 @@ AC_ARG_ENABLE([arm-neon],
 AM_CONDITIONAL([PNG_ARM_NEON],
   [test "$enable_arm_neon" != 'no' &&
    case "$host_cpu" in
-      arm*) :;;
+      arm*|aarch64*) :;;
      *)    test "$enable_arm_neon" != '';;
    esac])

--- a/example.c
+++ b/example.c
@@ -2,7 +2,7 @@
 #if 0 /* in case someone actually tries to compile this */

 /* example.c - an example of using libpng
- * Last changed in libpng 1.6.11 [June 5, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Maintained 1998-2014 Glenn Randers-Pehrson
 * Maintained 1996, 1997 Andreas Dilger)
 * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -52,7 +52,7 @@ int main(int argc, const char **argv)
      image.version = PNG_IMAGE_VERSION;

      /* The first argument is the file to read: */
-      if (png_image_begin_read_from_file(&image, argv[1]))
+      if (png_image_begin_read_from_file(&image, argv[1]) != 0)
      {
         png_bytep buffer;

@@ -97,7 +97,7 @@ int main(int argc, const char **argv)
          */
         if (buffer != NULL &&
            png_image_finish_read(&image, NULL/*background*/, buffer,
-               0/*row_stride*/, NULL/*colormap*/))
+               0/*row_stride*/, NULL/*colormap*/) != 0)
         {
            /* Now write the image out to the second argument.  In the write
             * call 'convert_to_8bit' allows 16-bit data to be squashed down to
@@ -105,7 +105,7 @@ int main(int argc, const char **argv)
             * to the 8-bit format.
             */
            if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
-               buffer, 0/*row_stride*/, NULL/*colormap*/))
+               buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
            {
               /* The image has been written successfully. */
               exit(0);
@@ -405,7 +405,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
   /* Expand paletted or RGB images with transparency to full alpha channels
    * so the data will be available as RGBA quartets.
    */
-   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) != 0)
      png_set_tRNS_to_alpha(png_ptr);

   /* Set the background color to draw transparent and alpha images over.
@@ -417,7 +417,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */

   png_color_16 my_background, *image_background;

-   if (png_get_bKGD(png_ptr, info_ptr, &image_background))
+   if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
      png_set_background(png_ptr, image_background,
                         PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
   else
@@ -454,12 +454,12 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */

   int intent;

-   if (png_get_sRGB(png_ptr, info_ptr, &intent))
+   if (png_get_sRGB(png_ptr, info_ptr, &intent) != 0)
      png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB);
   else
   {
      double image_gamma;
-      if (png_get_gAMA(png_ptr, info_ptr, &image_gamma))
+      if (png_get_gAMA(png_ptr, info_ptr, &image_gamma) != 0)
         png_set_gamma(png_ptr, screen_gamma, image_gamma);
      else
         png_set_gamma(png_ptr, screen_gamma, 0.45455);
@@ -469,7 +469,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
   /* Quantize RGB files down to 8 bit palette or reduce palettes
    * to the number of colors available on your screen.
    */
-   if (color_type & PNG_COLOR_MASK_COLOR)
+   if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      int num_palette;
      png_colorp palette;
@@ -484,7 +484,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
            MAX_SCREEN_COLORS, NULL, 0);
      }
      /* This reduces the image to the palette supplied in the file */
-      else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette))
+      else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
      {
         png_uint_16p histogram = NULL;

@@ -503,7 +503,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
    * [0,65535] to the original [0,7] or [0,31], or whatever range the
    * colors were originally in:
    */
-   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
+   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT) != 0)
   {
      png_color_8p sig_bit_p;

@@ -512,7 +512,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
   }

   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
-   if (color_type & PNG_COLOR_MASK_COLOR)
+   if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
      png_set_bgr(png_ptr);

   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
--- 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 1.6.15beta01 - October 29, 2014
+ libpng version 1.6.15beta04 - November 4, 2014
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2014 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 1.6.15beta01 - October 29, 2014
+ libpng versions 0.97, January 1998, through 1.6.15beta04 - November 4, 2014
 Updated and distributed by Glenn Randers-Pehrson
 Copyright (c) 1998-2014 Glenn Randers-Pehrson

@@ -5277,13 +5277,13 @@ Other rules can be inferred by inspecting the libpng source.

 XVI. Y2K Compliance in libpng

-October 29, 2014
+November 4, 2014

 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 1.6.15beta01 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.15beta04 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 "October 29, 2014"
+.TH LIBPNG 3 "November 4, 2014"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.15beta01
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.15beta04
 .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 1.6.15beta01 - October 29, 2014
+ libpng version 1.6.15beta04 - November 4, 2014
 Updated and distributed by Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2014 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 1.6.15beta01 - October 29, 2014
+ libpng versions 0.97, January 1998, through 1.6.15beta04 - November 4, 2014
 Updated and distributed by Glenn Randers-Pehrson
 Copyright (c) 1998-2014 Glenn Randers-Pehrson

@@ -5781,13 +5781,13 @@ Other rules can be inferred by inspecting the libpng source.

 .SH XVI. Y2K Compliance in libpng

-October 29, 2014
+November 4, 2014

 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 1.6.15beta01 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.15beta04 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
@@ -6033,7 +6033,7 @@ the first widely used release:
 1.6.14beta01-07     16    10614  16.so.16.14[.0]
 1.6.14rc01-02       16    10614  16.so.16.14[.0]
 1.6.14              16    10614  16.so.16.14[.0]
- 1.6.15beta01        16    10615  16.so.16.15[.0]
+ 1.6.15beta01-04     16    10615  16.so.16.15[.0]

 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6090,7 +6090,7 @@ possible without all of you.

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

-Libpng version 1.6.15beta01 - October 29, 2014:
+Libpng version 1.6.15beta04 - November 4, 2014:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).

@@ -6113,7 +6113,7 @@ this sentence.

 This code is released under the libpng license.

-libpng versions 1.2.6, August 15, 2004, through 1.6.15beta01, October 29, 2014, are
+libpng versions 1.2.6, August 15, 2004, through 1.6.15beta04, November 4, 2014, are
 Copyright (c) 2004,2006-2014 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
@@ -6212,7 +6212,7 @@ certification mark of the Open Source Initiative.

 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-October 29, 2014
+November 4, 2014

 .\" end of man page

--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "October 29, 2014"
+.TH LIBPNGPF 3 "November 4, 2014"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.15beta01
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.15beta04
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "October 29, 2014"
+.TH PNG 5 "November 4, 2014"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
--- a/png.c
+++ b/png.c
@@ -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_15beta01 Your_png_h_is_not_version_1_6_15beta01;
+typedef png_libpng_version_1_6_15beta04 Your_png_h_is_not_version_1_6_15beta04;

 /* 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
@@ -115,7 +115,7 @@ png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
 {
   int need_crc = 1;

-   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
+   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
   {
      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
@@ -124,7 +124,7 @@ png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)

   else /* critical */
   {
-      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+      if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
         need_crc = 0;
   }

@@ -133,7 +133,7 @@ png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
    * following cast is safe.  'uInt' may be no more than 16 bits, so it is
    * necessary to perform a loop here.
    */
-   if (need_crc && length > 0)
+   if (need_crc != 0 && length > 0)
   {
      uLong crc = png_ptr->crc; /* Should never issue a warning */

@@ -179,7 +179,7 @@ png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
   else
      png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;

-   if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
+   if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
   {
     /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
      * we must recompile any applications that use any older library version.
@@ -289,7 +289,7 @@ png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
 #  endif
         /* Call the general version checker (shared with read and write code):
          */
-         if (png_user_version_check(&create_struct, user_png_ver))
+         if (png_user_version_check(&create_struct, user_png_ver) != 0)
         {
            png_structrp png_ptr = png_voidcast(png_structrp,
               png_malloc_warn(&create_struct, (sizeof *png_ptr)));
@@ -451,7 +451,8 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_TEXT_SUPPORTED
   /* Free text item num or (if num == -1) all text items */
-   if (info_ptr->text && ((mask & PNG_FREE_TEXT) & info_ptr->free_me))
+   if (info_ptr->text != 0 &&
+       ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
   {
      if (num != -1)
      {
@@ -475,7 +476,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_tRNS_SUPPORTED
   /* Free any tRNS entry */
-   if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
+   if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
   {
      png_free(png_ptr, info_ptr->trans_alpha);
      info_ptr->trans_alpha = NULL;
@@ -485,7 +486,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_sCAL_SUPPORTED
   /* Free any sCAL entry */
-   if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
+   if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
   {
      png_free(png_ptr, info_ptr->scal_s_width);
      png_free(png_ptr, info_ptr->scal_s_height);
@@ -497,7 +498,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_pCAL_SUPPORTED
   /* Free any pCAL entry */
-   if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
+   if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
   {
      png_free(png_ptr, info_ptr->pcal_purpose);
      png_free(png_ptr, info_ptr->pcal_units);
@@ -520,7 +521,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_iCCP_SUPPORTED
   /* Free any profile entry */
-   if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
+   if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
   {
      png_free(png_ptr, info_ptr->iccp_name);
      png_free(png_ptr, info_ptr->iccp_profile);
@@ -532,7 +533,8 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_sPLT_SUPPORTED
   /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
-   if (info_ptr->splt_palettes && ((mask & PNG_FREE_SPLT) & info_ptr->free_me))
+   if (info_ptr->splt_palettes != 0 &&
+       ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
   {
      if (num != -1)
      {
@@ -544,7 +546,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

      else
      {
-         if (info_ptr->splt_palettes_num)
+         if (info_ptr->splt_palettes_num != 0)
         {
            int i;

@@ -564,7 +566,8 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
 #endif

 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
-   if (info_ptr->unknown_chunks && ((mask & PNG_FREE_UNKN) & info_ptr->free_me))
+   if (info_ptr->unknown_chunks != 0 &&
+       ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
   {
      if (num != -1)
      {
@@ -576,7 +579,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
      {
         int i;

-         if (info_ptr->unknown_chunks_num)
+         if (info_ptr->unknown_chunks_num != 0)
         {
            for (i = 0; i < info_ptr->unknown_chunks_num; i++)
               png_free(png_ptr, info_ptr->unknown_chunks[i].data);
@@ -591,7 +594,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_hIST_SUPPORTED
   /* Free any hIST entry */
-   if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
+   if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
   {
      png_free(png_ptr, info_ptr->hist);
      info_ptr->hist = NULL;
@@ -600,7 +603,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
 #endif

   /* Free any PLTE entry that was internally allocated */
-   if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
+   if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
   {
      png_free(png_ptr, info_ptr->palette);
      info_ptr->palette = NULL;
@@ -610,9 +613,9 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,

 #ifdef PNG_INFO_IMAGE_SUPPORTED
   /* Free any image bits attached to the info structure */
-   if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
+   if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
   {
-      if (info_ptr->row_pointers)
+      if (info_ptr->row_pointers != 0)
      {
         png_uint_32 row;
         for (row = 0; row < info_ptr->height; row++)
@@ -745,7 +748,7 @@ png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
   if (png_ptr != NULL)
   {
      /* The only failure above if png_ptr != NULL is from an invalid ptime */
-      if (!png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime))
+      if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
         png_warning(png_ptr, "Ignoring invalid time value");

      else
@@ -768,13 +771,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
   return PNG_STRING_NEWLINE \
-     "libpng version 1.6.15beta01 - October 29, 2014" PNG_STRING_NEWLINE \
+     "libpng version 1.6.15beta04 - November 4, 2014" PNG_STRING_NEWLINE \
     "Copyright (c) 1998-2014 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 1.6.15beta01 - October 29, 2014\
+      return "libpng version 1.6.15beta04 - November 4, 2014\
      Copyright (c) 1998-2014 Glenn Randers-Pehrson\
      Copyright (c) 1996-1997 Andreas Dilger\
      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -899,7 +902,7 @@ png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
   {
      p -= 5;

-      if (!memcmp(chunk_name, p, 4))
+      if (memcmp(chunk_name, p, 4) == 0)
         return p[4];
   }
   while (p > p_end);
@@ -1041,8 +1044,8 @@ png_colorspace_check_gamma(png_const_structrp png_ptr,
   png_fixed_point gtest;

   if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
-      (!png_muldiv(&gtest, colorspace->gamma, PNG_FP_1, gAMA) ||
-      png_gamma_significant(gtest)))
+      (png_muldiv(&gtest, colorspace->gamma, PNG_FP_1, gAMA) == 0  ||
+      png_gamma_significant(gtest) != 0))
   {
      /* Either this is an sRGB image, in which case the calculated gamma
       * approximation should match, or this is an image with a profile and the
@@ -1097,12 +1100,13 @@ png_colorspace_set_gamma(png_const_structrp png_ptr,
 #  endif

   /* Do nothing if the colorspace is already invalid */
-   else if (colorspace->flags & PNG_COLORSPACE_INVALID)
+   else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return;

   else
   {
-      if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA, 1/*from gAMA*/))
+      if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
+          1/*from gAMA*/) != 0)
      {
         /* Store this gamma value. */
         colorspace->gamma = gAMA;
@@ -1126,7 +1130,7 @@ png_colorspace_set_gamma(png_const_structrp png_ptr,
 void /* PRIVATE */
 png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
 {
-   if (info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+   if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
   {
      /* Everything is invalid */
      info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
@@ -1147,20 +1151,20 @@ png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
          * it; this allows a PNG to contain a profile which matches sRGB and
          * yet still have that profile retrievable by the application.
          */
-         if (info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB)
+         if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
            info_ptr->valid |= PNG_INFO_sRGB;

         else
            info_ptr->valid &= ~PNG_INFO_sRGB;

-         if (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS)
+         if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
            info_ptr->valid |= PNG_INFO_cHRM;

         else
            info_ptr->valid &= ~PNG_INFO_cHRM;
 #     endif

-      if (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA)
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
         info_ptr->valid |= PNG_INFO_gAMA;

      else
@@ -1193,22 +1197,28 @@ png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
   png_int_32 d, dwhite, whiteX, whiteY;

   d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
-   if (!png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d)) return 1;
-   if (!png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d)) return 1;
+   if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
+      return 1;
+   if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
+      return 1;
   dwhite = d;
   whiteX = XYZ->red_X;
   whiteY = XYZ->red_Y;

   d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
-   if (!png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d)) return 1;
-   if (!png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d)) return 1;
+   if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
+      return 1;
+   if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
+      return 1;
   dwhite += d;
   whiteX += XYZ->green_X;
   whiteY += XYZ->green_Y;

   d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
-   if (!png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d)) return 1;
-   if (!png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d)) return 1;
+   if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
+      return 1;
+   if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
+      return 1;
   dwhite += d;
   whiteX += XYZ->blue_X;
   whiteY += XYZ->blue_Y;
@@ -1216,8 +1226,10 @@ png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
   /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
    * thus:
    */
-   if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
-   if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
+   if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
+      return 1;
+   if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
+      return 1;

   return 0;
 }
@@ -1420,16 +1432,16 @@ png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
   /* By the argument, above overflow should be impossible here. The return
    * value of 2 indicates an internal error to the caller.
    */
-   if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7))
+   if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
      return 2;
-   if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7))
+   if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
      return 2;
   denominator = left - right;

   /* Now find the red numerator. */
-   if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7))
+   if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
      return 2;
-   if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7))
+   if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
      return 2;

   /* Overflow is possible here and it indicates an extreme set of PNG cHRM
@@ -1437,16 +1449,16 @@ png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
    * scale value because this allows us to delay the multiplication of white-y
    * into the denominator, which tends to produce a small number.
    */
-   if (!png_muldiv(&red_inverse, xy->whitey, denominator, left-right) ||
+   if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
       red_inverse <= xy->whitey /* r+g+b scales = white scale */)
      return 1;

   /* Similarly for green_inverse: */
-   if (!png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7))
+   if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
      return 2;
-   if (!png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7))
+   if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
      return 2;
-   if (!png_muldiv(&green_inverse, xy->whitey, denominator, left-right) ||
+   if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
       green_inverse <= xy->whitey)
      return 1;

@@ -1454,29 +1466,34 @@ png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
    * can still produce 0 for extreme cHRM values.
    */
   blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
-      png_reciprocal(green_inverse);
-   if (blue_scale <= 0) return 1;
+       png_reciprocal(green_inverse);
+   if (blue_scale <= 0)
+      return 1;


   /* And fill in the png_XYZ: */
-   if (!png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse)) return 1;
-   if (!png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse)) return 1;
-   if (!png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
-      red_inverse))
+   if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
+       red_inverse) == 0)
      return 1;

-   if (!png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse))
+   if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
      return 1;
-   if (!png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse))
+   if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
      return 1;
-   if (!png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
-      green_inverse))
+   if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
+       green_inverse) == 0)
      return 1;

-   if (!png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1)) return 1;
-   if (!png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1)) return 1;
-   if (!png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
-      PNG_FP_1))
+   if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
+      return 1;
+   if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
+       PNG_FP_1) == 0)
      return 1;

   return 0; /*success*/
@@ -1498,24 +1515,35 @@ png_XYZ_normalize(png_XYZ *XYZ)
    * safe.
    */
   Y = XYZ->red_Y;
-   if (0x7fffffff - Y < XYZ->green_X) return 1;
+   if (0x7fffffff - Y < XYZ->green_X)
+      return 1;
   Y += XYZ->green_Y;
-   if (0x7fffffff - Y < XYZ->blue_X) return 1;
+   if (0x7fffffff - Y < XYZ->blue_X)
+      return 1;
   Y += XYZ->blue_Y;

   if (Y != PNG_FP_1)
   {
-      if (!png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y)) return 1;
-      if (!png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y)) return 1;
-      if (!png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y)) return 1;
+      if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
+         return 1;

-      if (!png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y)) return 1;
-      if (!png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y)) return 1;
-      if (!png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y)) return 1;
+      if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
+         return 1;

-      if (!png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y)) return 1;
-      if (!png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y)) return 1;
-      if (!png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y)) return 1;
+      if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
+         return 1;
+      if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
+         return 1;
   }

   return 0;
@@ -1525,14 +1553,16 @@ static int
 png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
 {
   /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
-   return !(PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
-      PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
-      PNG_OUT_OF_RANGE(xy1->redx,   xy2->redx,  delta) ||
-      PNG_OUT_OF_RANGE(xy1->redy,   xy2->redy,  delta) ||
-      PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
-      PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
-      PNG_OUT_OF_RANGE(xy1->bluex,  xy2->bluex, delta) ||
-      PNG_OUT_OF_RANGE(xy1->bluey,  xy2->bluey, delta));
+   if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
+       PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
+       PNG_OUT_OF_RANGE(xy1->redx,   xy2->redx,  delta) ||
+       PNG_OUT_OF_RANGE(xy1->redy,   xy2->redy,  delta) ||
+       PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
+       PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
+       PNG_OUT_OF_RANGE(xy1->bluex,  xy2->bluex, delta) ||
+       PNG_OUT_OF_RANGE(xy1->bluey,  xy2->bluey, delta))
+      return 0;
+   return 1;
 }

 /* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
@@ -1553,13 +1583,15 @@ png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)

   /* As a side-effect this routine also returns the XYZ endpoints. */
   result = png_XYZ_from_xy(XYZ, xy);
-   if (result != 0) return result;
+   if (result != 0)
+      return result;

   result = png_xy_from_XYZ(&xy_test, XYZ);
-   if (result != 0) return result;
+   if (result != 0)
+      return result;

   if (png_colorspace_endpoints_match(xy, &xy_test,
-      5/*actually, the math is pretty accurate*/))
+       5/*actually, the math is pretty accurate*/) != 0)
      return 0;

   /* Too much slip */
@@ -1576,10 +1608,12 @@ png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
   png_XYZ XYZtemp;

   result = png_XYZ_normalize(XYZ);
-   if (result != 0) return result;
+   if (result != 0)
+      return result;

   result = png_xy_from_XYZ(xy, XYZ);
-   if (result != 0) return result;
+   if (result != 0)
+      return result;

   XYZtemp = *XYZ;
   return png_colorspace_check_xy(&XYZtemp, xy);
@@ -1600,19 +1634,21 @@ png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
   png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
   int preferred)
 {
-   if (colorspace->flags & PNG_COLORSPACE_INVALID)
+   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;

   /* The consistency check is performed on the chromaticities; this factors out
    * variations because of the normalization (or not) of the end point Y
    * values.
    */
-   if (preferred < 2 && (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+   if (preferred < 2 &&
+       (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      /* The end points must be reasonably close to any we already have.  The
       * following allows an error of up to +/-.001
       */
-      if (!png_colorspace_endpoints_match(xy, &colorspace->end_points_xy, 100))
+      if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
+          100) == 0)
      {
         colorspace->flags |= PNG_COLORSPACE_INVALID;
         png_benign_error(png_ptr, "inconsistent chromaticities");
@@ -1631,7 +1667,7 @@ png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
   /* The end points are normally quoted to two decimal digits, so allow +/-0.01
    * on this test.
    */
-   if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000))
+   if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
      colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;

   else
@@ -1759,7 +1795,7 @@ png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
   pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
   pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
   pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
-   if (is_ICC_signature(value))
+   if (is_ICC_signature(value) != 0)
   {
      /* So 'value' is at most 4 bytes and the following cast is safe */
      png_icc_tag_name(message+pos, (png_uint_32)value);
@@ -1820,7 +1856,7 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
   };

   /* Do nothing if the colorspace is already invalidated. */
-   if (colorspace->flags & PNG_COLORSPACE_INVALID)
+   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;

   /* Check the intent, then check for existing settings.  It is valid for the
@@ -1999,13 +2035,13 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
   switch (temp)
   {
      case 0x52474220: /* 'RGB ' */
-         if (!(color_type & PNG_COLOR_MASK_COLOR))
+         if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
            return png_icc_profile_error(png_ptr, colorspace, name, temp,
               "RGB color space not permitted on grayscale PNG");
         break;

      case 0x47524159: /* 'GRAY' */
-         if (color_type & PNG_COLOR_MASK_COLOR)
+         if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
            return png_icc_profile_error(png_ptr, colorspace, name, temp,
               "Gray color space not permitted on RGB PNG");
         break;
@@ -2233,7 +2269,7 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
          * are not used by default if there is an MD5!)
          */
 #        if PNG_sRGB_PROFILE_CHECKS == 0
-            if (png_sRGB_checks[i].have_md5)
+            if (png_sRGB_checks[i].have_md5 != 0)
               return 1+png_sRGB_checks[i].is_broken;
 #        endif

@@ -2273,7 +2309,7 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
                  if (crc == png_sRGB_checks[i].crc)
 #              endif
               {
-                  if (png_sRGB_checks[i].is_broken)
+                  if (png_sRGB_checks[i].is_broken != 0)
                  {
                     /* These profiles are known to have bad data that may cause
                      * problems if they are used, therefore attempt to
@@ -2288,7 +2324,7 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
                   * the profile is perfectly valid, but it would be nice if
                   * people used the up-to-date ones.
                   */
-                  else if (!png_sRGB_checks[i].have_md5)
+                  else if (png_sRGB_checks[i].have_md5 == 0)
                  {
                     png_chunk_report(png_ptr, "out-of-date sRGB profile with"
                        " no signature",
@@ -2326,7 +2362,7 @@ png_icc_set_sRGB(png_const_structrp png_ptr,
    * the sRGB information.
    */
 #if PNG_sRGB_PROFILE_CHECKS >= 0
-   if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler))
+   if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
 #endif
      (void)png_colorspace_set_sRGB(png_ptr, colorspace,
         (int)/*already checked*/png_get_uint_32(profile+64));
@@ -2338,14 +2374,14 @@ png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
   png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
   int color_type)
 {
-   if (colorspace->flags & PNG_COLORSPACE_INVALID)
+   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;

-   if (png_icc_check_length(png_ptr, colorspace, name, profile_length) &&
-      png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
-         color_type) &&
-      png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
-         profile))
+   if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
+       png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
+          color_type) != 0 &&
+       png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
+          profile) != 0)
   {
 #     ifdef PNG_sRGB_SUPPORTED
         /* If no sRGB support, don't try storing sRGB information */
@@ -2364,7 +2400,7 @@ void /* PRIVATE */
 png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
 {
   /* Set the rgb_to_gray coefficients from the colorspace. */
-   if (!png_ptr->rgb_to_gray_coefficients_set &&
+   if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
      (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      /* png_set_background has not been called, get the coefficients from the Y
@@ -2528,13 +2564,13 @@ png_check_IHDR(png_const_structrp png_ptr,
    * 4. The filter_method is 64 and
    * 5. The color_type is RGB or RGBA
    */
-   if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
-       png_ptr->mng_features_permitted)
+   if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
+       png_ptr->mng_features_permitted != 0)
      png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");

   if (filter_type != PNG_FILTER_TYPE_BASE)
   {
-      if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+      if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
          (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
          ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
          (color_type == PNG_COLOR_TYPE_RGB ||
@@ -2544,7 +2580,7 @@ png_check_IHDR(png_const_structrp png_ptr,
         error = 1;
      }

-      if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
+      if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
      {
         png_warning(png_ptr, "Invalid filter method in IHDR");
         error = 1;
@@ -2604,7 +2640,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
      switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
      {
      case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
-         if (state & PNG_FP_SAW_ANY)
+         if ((state & PNG_FP_SAW_ANY) != 0)
            goto PNG_FP_End; /* not a part of the number */

         png_fp_add(state, type);
@@ -2612,10 +2648,10 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,

      case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
         /* Ok as trailer, ok as lead of fraction. */
-         if (state & PNG_FP_SAW_DOT) /* two dots */
+         if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
            goto PNG_FP_End;

-         else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */
+         else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
            png_fp_add(state, type);

         else
@@ -2624,7 +2660,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
         break;

      case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
-         if (state & PNG_FP_SAW_DOT) /* delayed fraction */
+         if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
            png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);

         png_fp_add(state, type | PNG_FP_WAS_VALID);
@@ -2662,7 +2698,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
         break;

      case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
-         if (state & PNG_FP_SAW_ANY)
+         if ((state & PNG_FP_SAW_ANY) != 0)
            goto PNG_FP_End; /* not a part of the number */

         png_fp_add(state, PNG_FP_SAW_SIGN);
@@ -2705,7 +2741,7 @@ png_check_fp_string(png_const_charp string, png_size_t size)
   int        state=0;
   png_size_t char_index=0;

-   if (png_check_fp_number(string, size, &state, &char_index) &&
+   if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
      (char_index == size || string[char_index] == 0))
      return state /* must be non-zero - see above */;

@@ -2959,8 +2995,9 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,

                  if (exp_b10 != (-1))
                  {
-                     if (exp_b10 == 0) *ascii++ = 46, --size; /* counted
-                                                                 above */
+                     if (exp_b10 == 0)
+                        *ascii++ = 46, --size; /* counted above */
+
                     --exp_b10;
                  }
                  *ascii++ = (char)(48 + (int)d), ++cdigits;
@@ -3297,7 +3334,7 @@ png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
 {
   png_fixed_point result;

-   if (png_muldiv(&result, a, times, divisor))
+   if (png_muldiv(&result, a, times, divisor) != 0)
      return result;

   png_warning(png_ptr, "fixed point overflow ignored");
@@ -3318,7 +3355,7 @@ png_reciprocal(png_fixed_point a)
 #else
   png_fixed_point res;

-   if (png_muldiv(&res, 100000, 100000, a))
+   if (png_muldiv(&res, 100000, 100000, a) != 0)
      return res;
 #endif

@@ -3353,7 +3390,7 @@ png_product2(png_fixed_point a, png_fixed_point b)
 #    else
   png_fixed_point res;

-   if (png_muldiv(&res, a, b, 100000))
+   if (png_muldiv(&res, a, b, 100000) != 0)
      return res;
 #    endif

@@ -3690,7 +3727,7 @@ png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
         png_int_32 lg2 = png_log8bit(value);
         png_fixed_point res;

-         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
+         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
            return png_exp8bit(res);

         /* Overflow. */
@@ -3714,7 +3751,7 @@ png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
         png_int_32 lg2 = png_log16bit(value);
         png_fixed_point res;

-         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
+         if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
            return png_exp16bit(res);

         /* Overflow. */
@@ -3777,7 +3814,7 @@ png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
      /* The 'threshold' test is repeated here because it can arise for one of
       * the 16-bit tables even if the others don't hit it.
       */
-      if (png_gamma_significant(gamma_val))
+      if (png_gamma_significant(gamma_val) != 0)
      {
         /* The old code would overflow at the end and this would cause the
          * 'pow' function to return a result >1, resulting in an
@@ -3899,11 +3936,13 @@ png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
   unsigned int i;
   png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);

-   if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++)
-      table[i] = png_gamma_8bit_correct(i, gamma_val);
+   if (png_gamma_significant(gamma_val) != 0)
+      for (i=0; i<256; i++)
+         table[i] = png_gamma_8bit_correct(i, gamma_val);

-   else for (i=0; i<256; ++i)
-      table[i] = (png_byte)i;
+   else
+      for (i=0; i<256; ++i)
+         table[i] = (png_byte)i;
 }

 /* Used from png_read_destroy and below to release the memory used by the gamma
@@ -3995,7 +4034,7 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-     if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
+     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
     {
        png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
            png_reciprocal(png_ptr->colorspace.gamma));
@@ -4011,7 +4050,7 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
  {
     png_byte shift, sig_bit;

-     if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+     if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
     {
        sig_bit = png_ptr->sig_bit.red;

@@ -4048,7 +4087,7 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
     else
        shift = 0; /* keep all 16 bits */

-     if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
+     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
     {
        /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
         * the significant bits in the *input* when the output will
@@ -4068,7 +4107,7 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
      * 16-bit output because the 8-bit table assumes the result will be reduced
      * to 8 bits.
      */
-     if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
+     if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
         png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
         png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
         png_ptr->screen_gamma) : PNG_FP_1);
@@ -4081,7 +4120,7 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
   defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
   defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-     if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
+     if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
     {
        png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
            png_reciprocal(png_ptr->colorspace.gamma));
@@ -4307,7 +4346,7 @@ png_image_free_function(png_voidp argument)

   /* First free any data held in the control structure. */
 #  ifdef PNG_STDIO_SUPPORTED
-      if (cp->owned_file)
+      if (cp->owned_file != 0)
      {
         FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
         cp->owned_file = 0;
@@ -4331,7 +4370,7 @@ png_image_free_function(png_voidp argument)
   png_free(c.png_ptr, cp);

   /* Then the structures, calling the correct API. */
-   if (c.for_write)
+   if (c.for_write != 0)
   {
 #     ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
         png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@

 /* png.h - header file for PNG reference library
 *
- * libpng version 1.6.15beta01 - October 29, 2014
+ * libpng version 1.6.15beta04 - November 4, 2014
 * Copyright (c) 1998-2014 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.)
@@ -11,7 +11,7 @@
 * 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 1.6.15beta01 - October 29, 2014: Glenn
+ *   libpng versions 0.97, January 1998, through 1.6.15beta04 - November 4, 2014: Glenn
 *   See also "Contributing Authors", below.
 *
 * Note about libpng version numbers:
@@ -206,7 +206,7 @@
 *    1.6.14beta01-07         16    10614  16.so.16.14[.0]
 *    1.6.14rc01-02           16    10614  16.so.16.14[.0]
 *    1.6.14                  16    10614  16.so.16.14[.0]
- *    1.6.15beta01            16    10615  16.so.16.15[.0]
+ *    1.6.15beta01-04         16    10615  16.so.16.15[.0]
 *
 *   Henceforth the source version will match the shared-library major
 *   and minor numbers; the shared-library major version number will be
@@ -238,7 +238,7 @@
 *
 * This code is released under the libpng license.
 *
- * libpng versions 1.2.6, August 15, 2004, through 1.6.15beta01, October 29, 2014, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.6.15beta04, November 4, 2014, are
 * Copyright (c) 2004, 2006-2014 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:
@@ -350,13 +350,13 @@
 * Y2K compliance in libpng:
 * =========================
 *
- *    October 29, 2014
+ *    November 4, 2014
 *
 *    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 1.6.15beta01 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.15beta04 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
@@ -418,9 +418,9 @@
 */

 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.15beta01"
+#define PNG_LIBPNG_VER_STRING "1.6.15beta04"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.15beta01 - October 29, 2014\n"
+     " libpng version 1.6.15beta04 - November 4, 2014\n"

 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -434,7 +434,7 @@
 * PNG_LIBPNG_VER_STRING, omitting any leading zero:
 */

-#define PNG_LIBPNG_VER_BUILD  01
+#define PNG_LIBPNG_VER_BUILD  04

 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
@@ -564,7 +564,7 @@ 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_15beta01;
+typedef char* png_libpng_version_1_6_15beta04;

 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 *
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@

 /* pngconf.h - machine configurable file for libpng
 *
- * libpng version 1.6.15beta01 - October 29, 2014
+ * libpng version 1.6.15beta04 - November 4, 2014
 *
 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,7 +1,7 @@

 /* pngerror.c - stub functions for i/o and memory allocation
 *
- * Last changed in libpng 1.6.13 [August 21, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -43,8 +43,8 @@ png_error,(png_const_structrp png_ptr, png_const_charp error_message),
   char msg[16];
   if (png_ptr != NULL)
   {
-      if (png_ptr->flags&
-         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+      if ((png_ptr->flags &
+         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0
      {
         if (*error_message == PNG_LITERAL_SHARP)
         {
@@ -54,7 +54,7 @@ png_error,(png_const_structrp png_ptr, png_const_charp error_message),
               if (error_message[offset] == ' ')
                  break;

-            if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+            if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
            {
               int i;
               for (i = 0; i < offset - 1; i++)
@@ -69,7 +69,7 @@ png_error,(png_const_structrp png_ptr, png_const_charp error_message),

      else
      {
-         if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+         if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
         {
            msg[0] = '0';
            msg[1] = '\0';
@@ -152,7 +152,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
         case PNG_NUMBER_FORMAT_fixed:
            /* Needs five digits (the fraction) */
            mincount = 5;
-            if (output || number % 10 != 0)
+            if (output != 0 || number % 10 != 0)
            {
               *--end = digits[number % 10];
               output = 1;
@@ -189,7 +189,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
      ++count;

      /* Float a fixed number here: */
-      if (format == PNG_NUMBER_FORMAT_fixed) if (count == 5) if (end > start)
+      if ((format == PNG_NUMBER_FORMAT_fixed) && (count == 5) && (end > start))
      {
         /* End of the fraction, but maybe nothing was output?  In that case
          * drop the decimal point.  If the number is a true zero handle that
@@ -219,8 +219,8 @@ png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
   if (png_ptr != NULL)
   {
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-   if (png_ptr->flags&
-       (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
+   if ((png_ptr->flags &
+       (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
 #endif
      {
         if (*warning_message == PNG_LITERAL_SHARP)
@@ -361,7 +361,7 @@ png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
 void PNGAPI
 png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
 {
-   if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+   if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
   {
 #     ifdef PNG_READ_SUPPORTED
         if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
@@ -391,7 +391,7 @@ png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
 void /* PRIVATE */
 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
 {
-  if (png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN)
+  if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
     png_warning(png_ptr, error_message);
  else
     png_error(png_ptr, error_message);
@@ -404,7 +404,7 @@ png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
 void /* PRIVATE */
 png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
 {
-  if (png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN)
+  if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
     png_warning(png_ptr, error_message);
  else
     png_error(png_ptr, error_message);
@@ -442,7 +442,7 @@ png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
      int c = (int)(chunk_name >> ishift) & 0xff;

      ishift -= 8;
-      if (isnonalpha(c))
+      if (isnonalpha(c) != 0)
      {
         buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
         buffer[iout++] = png_digit[(c & 0xf0) >> 4];
@@ -514,7 +514,7 @@ void PNGAPI
 png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
    error_message)
 {
-   if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+   if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
      png_chunk_warning(png_ptr, error_message);

   else
@@ -538,7 +538,7 @@ png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
    * unconditionally does the right thing.
    */
 #  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
-      if (png_ptr->mode & PNG_IS_READ_STRUCT)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
 #  endif

 #  ifdef PNG_READ_SUPPORTED
@@ -552,7 +552,7 @@ png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
 #  endif

 #  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
-      else if (!(png_ptr->mode & PNG_IS_READ_STRUCT))
+      else if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
 #  endif

 #  ifdef PNG_WRITE_SUPPORTED
@@ -577,11 +577,12 @@ png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
   char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
   memcpy(msg, fixed_message, fixed_message_ln);
   iin = 0;
-   if (name != NULL) while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
-   {
-      msg[fixed_message_ln + iin] = name[iin];
-      ++iin;
-   }
+   if (name != NULL)
+      while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
+      {
+         msg[fixed_message_ln + iin] = name[iin];
+         ++iin;
+      }
   msg[fixed_message_ln + iin] = 0;
   png_error(png_ptr, msg);
 }
@@ -757,7 +758,8 @@ PNG_FUNCTION(void,PNGAPI
 png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
 {
 #ifdef PNG_SETJMP_SUPPORTED
-   if (png_ptr && png_ptr->longjmp_fn && png_ptr->jmp_buf_ptr)
+   if (png_ptr != NULL && png_ptr->longjmp_fn != NULL &&
+       png_ptr->jmp_buf_ptr != NULL)
      png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
 #else
   PNG_UNUSED(png_ptr)
--- a/pngget.c
+++ b/pngget.c
@@ -1,7 +1,7 @@

 /* pngget.c - retrieval of values from info struct
 *
- * Last changed in libpng 1.6.11 [June 5, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -116,7 +116,8 @@ png_get_x_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp
   info_ptr)
 {
 #ifdef PNG_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
      {
         png_debug1(1, "in %s retrieval function",
             "png_get_x_pixels_per_meter");
@@ -137,7 +138,8 @@ png_get_y_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp
    info_ptr)
 {
 #ifdef PNG_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
   {
      png_debug1(1, "in %s retrieval function",
          "png_get_y_pixels_per_meter");
@@ -157,7 +159,8 @@ png_uint_32 PNGAPI
 png_get_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "png_get_pixels_per_meter");

@@ -179,7 +182,8 @@ png_get_pixel_aspect_ratio(png_const_structrp png_ptr, png_const_inforp
   info_ptr)
 {
 #ifdef PNG_READ_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "png_get_aspect_ratio");

@@ -202,10 +206,11 @@ png_get_pixel_aspect_ratio_fixed(png_const_structrp png_ptr,
    png_const_inforp info_ptr)
 {
 #ifdef PNG_READ_pHYs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs)
-       && info_ptr->x_pixels_per_unit > 0 && info_ptr->y_pixels_per_unit > 0
-       && info_ptr->x_pixels_per_unit <= PNG_UINT_31_MAX
-       && info_ptr->y_pixels_per_unit <= PNG_UINT_31_MAX)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0 &&
+       info_ptr->x_pixels_per_unit > 0 && info_ptr->y_pixels_per_unit > 0 &&
+       info_ptr->x_pixels_per_unit <= PNG_UINT_31_MAX &&
+       info_ptr->y_pixels_per_unit <= PNG_UINT_31_MAX)
   {
      png_fixed_point res;

@@ -215,7 +220,7 @@ png_get_pixel_aspect_ratio_fixed(png_const_structrp png_ptr,
       * range of 0..2^31-1; otherwise the cast might overflow.
       */
      if (png_muldiv(&res, (png_int_32)info_ptr->y_pixels_per_unit, PNG_FP_1,
-          (png_int_32)info_ptr->x_pixels_per_unit))
+          (png_int_32)info_ptr->x_pixels_per_unit) != 0)
         return res;
   }
 #else
@@ -231,7 +236,8 @@ png_int_32 PNGAPI
 png_get_x_offset_microns(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "png_get_x_offset_microns");

@@ -250,7 +256,8 @@ png_int_32 PNGAPI
 png_get_y_offset_microns(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "png_get_y_offset_microns");

@@ -269,7 +276,8 @@ png_int_32 PNGAPI
 png_get_x_offset_pixels(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "png_get_x_offset_pixels");

@@ -288,7 +296,8 @@ png_int_32 PNGAPI
 png_get_y_offset_pixels(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
 #ifdef PNG_oFFs_SUPPORTED
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "png_get_y_offset_pixels");

@@ -328,7 +337,7 @@ ppi_from_ppm(png_uint_32 ppm)
    */
   png_fixed_point result;
   if (ppm <= PNG_UINT_31_MAX && png_muldiv(&result, (png_int_32)ppm, 127,
-       5000))
+       5000) != 0)
      return result;

   /* Overflow. */
@@ -414,7 +423,8 @@ png_get_pHYs_dpi(png_const_structrp png_ptr, png_const_inforp info_ptr,
 {
   png_uint_32 retval = 0;

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
   {
      png_debug1(1, "in %s retrieval function", "pHYs");

@@ -478,8 +488,9 @@ png_uint_32 PNGAPI
 png_get_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
   png_color_16p *background)
 {
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD)
-       && background != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_bKGD) != 0 &&
+       background != NULL)
   {
      png_debug1(1, "in %s retrieval function", "bKGD");

@@ -509,7 +520,7 @@ png_get_cHRM(png_const_structrp png_ptr, png_const_inforp info_ptr,
    * consistent.
    */
   if (png_ptr != NULL && info_ptr != NULL &&
-      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      png_debug1(1, "in %s retrieval function", "cHRM");

@@ -550,7 +561,7 @@ png_get_cHRM_XYZ(png_const_structrp png_ptr, png_const_inforp info_ptr,
   double *blue_Z)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
-      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      png_debug1(1, "in %s retrieval function", "cHRM_XYZ(float)");

@@ -598,7 +609,7 @@ png_get_cHRM_XYZ_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
    png_fixed_point *int_blue_Z)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
-      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      png_debug1(1, "in %s retrieval function", "cHRM_XYZ");

@@ -635,7 +646,7 @@ png_get_cHRM_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
   png_debug1(1, "in %s retrieval function", "cHRM");

   if (png_ptr != NULL && info_ptr != NULL &&
-      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
   {
      if (white_x != NULL)
         *white_x = info_ptr->colorspace.end_points_xy.whitex;
@@ -670,7 +681,7 @@ png_get_gAMA_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
   png_debug1(1, "in %s retrieval function", "gAMA");

   if (png_ptr != NULL && info_ptr != NULL &&
-      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
      file_gamma != NULL)
   {
      *file_gamma = info_ptr->colorspace.gamma;
@@ -689,7 +700,7 @@ png_get_gAMA(png_const_structrp png_ptr, png_const_inforp info_ptr,
   png_debug1(1, "in %s retrieval function", "gAMA(float)");

   if (png_ptr != NULL && info_ptr != NULL &&
-      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) &&
+      (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
      file_gamma != NULL)
   {
      *file_gamma = png_float(png_ptr, info_ptr->colorspace.gamma,
@@ -709,8 +720,8 @@ png_get_sRGB(png_const_structrp png_ptr, png_const_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "sRGB");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB)
-       && file_srgb_intent != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+      (info_ptr->valid & PNG_INFO_sRGB) != 0 && file_srgb_intent != NULL)
   {
      *file_srgb_intent = info_ptr->colorspace.rendering_intent;
      return (PNG_INFO_sRGB);
@@ -728,9 +739,10 @@ png_get_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "iCCP");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP)
-       && name != NULL && compression_type != NULL && profile != NULL &&
-		 proflen != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_iCCP) != 0 &&
+       name != NULL && compression_type != NULL && profile != NULL &&
+           proflen != NULL)
   {
      *name = info_ptr->iccp_name;
      *profile = info_ptr->iccp_profile;
@@ -768,8 +780,8 @@ png_get_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "hIST");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST)
-       && hist != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_hIST) != 0 && hist != NULL)
   {
      *hist = info_ptr->hist;
      return (PNG_INFO_hIST);
@@ -824,8 +836,9 @@ png_get_oFFs(png_const_structrp png_ptr, png_const_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "oFFs");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs)
-       && offset_x != NULL && offset_y != NULL && unit_type != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_oFFs) != 0 &&
+       offset_x != NULL && offset_y != NULL && unit_type != NULL)
   {
      *offset_x = info_ptr->x_offset;
      *offset_y = info_ptr->y_offset;
@@ -845,8 +858,9 @@ png_get_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "pCAL");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL)
-       && purpose != NULL && X0 != NULL && X1 != NULL && type != NULL &&
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_pCAL) != 0 &&
+       purpose != NULL && X0 != NULL && X1 != NULL && type != NULL &&
       nparams != NULL && units != NULL && params != NULL)
   {
      *purpose = info_ptr->pcal_purpose;
@@ -872,7 +886,7 @@ png_get_sCAL_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
    int *unit, png_fixed_point *width, png_fixed_point *height)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_sCAL))
+       (info_ptr->valid & PNG_INFO_sCAL) != 0)
   {
      *unit = info_ptr->scal_unit;
      /*TODO: make this work without FP support; the API is currently eliminated
@@ -895,7 +909,7 @@ png_get_sCAL(png_const_structrp png_ptr, png_const_inforp info_ptr,
    int *unit, double *width, double *height)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_sCAL))
+       (info_ptr->valid & PNG_INFO_sCAL) != 0)
   {
      *unit = info_ptr->scal_unit;
      *width = atof(info_ptr->scal_s_width);
@@ -911,7 +925,7 @@ png_get_sCAL_s(png_const_structrp png_ptr, png_const_inforp info_ptr,
    int *unit, png_charpp width, png_charpp height)
 {
   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_sCAL))
+       (info_ptr->valid & PNG_INFO_sCAL) != 0)
   {
      *unit = info_ptr->scal_unit;
      *width = info_ptr->scal_s_width;
@@ -933,7 +947,7 @@ png_get_pHYs(png_const_structrp png_ptr, png_const_inforp info_ptr,
   png_debug1(1, "in %s retrieval function", "pHYs");

   if (png_ptr != NULL && info_ptr != NULL &&
-       (info_ptr->valid & PNG_INFO_pHYs))
+       (info_ptr->valid & PNG_INFO_pHYs) != 0)
   {
      if (res_x != NULL)
      {
@@ -964,8 +978,8 @@ png_get_PLTE(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "PLTE");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_PLTE)
-       && palette != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_PLTE) != 0 && palette != NULL)
   {
      *palette = info_ptr->palette;
      *num_palette = info_ptr->num_palette;
@@ -983,8 +997,8 @@ png_get_sBIT(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "sBIT");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT)
-       && sig_bit != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_sBIT) != 0 && sig_bit != NULL)
   {
      *sig_bit = &(info_ptr->sig_bit);
      return (PNG_INFO_sBIT);
@@ -1027,8 +1041,8 @@ png_get_tIME(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_debug1(1, "in %s retrieval function", "tIME");

-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME)
-       && mod_time != NULL)
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_tIME) != 0 && mod_time != NULL)
   {
      *mod_time = &(info_ptr->mod_time);
      return (PNG_INFO_tIME);
@@ -1044,7 +1058,8 @@ png_get_tRNS(png_const_structrp png_ptr, png_inforp info_ptr,
    png_bytep *trans_alpha, int *num_trans, png_color_16p *trans_color)
 {
   png_uint_32 retval = 0;
-   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+   if (png_ptr != NULL && info_ptr != NULL &&
+       (info_ptr->valid & PNG_INFO_tRNS) != 0)
   {
      png_debug1(1, "in %s retrieval function", "tRNS");

@@ -1121,7 +1136,7 @@ png_get_compression_buffer_size(png_const_structrp png_ptr)
      return 0;

 #  ifdef PNG_WRITE_SUPPORTED
-      if (png_ptr->mode & PNG_IS_READ_STRUCT)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
 #  endif
   {
 #     ifdef PNG_SEQUENTIAL_READ_SUPPORTED
--- a/pngpread.c
+++ b/pngpread.c
@@ -202,7 +202,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
    * sure we have enough data in the buffer for the 4-byte CRC at the
    * end of every chunk (except IDAT, which is handled separately).
    */
-   if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
+   if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
   {
      png_byte chunk_length[4];
      png_byte chunk_tag[4];
@@ -221,28 +221,28 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)

   if (chunk_name == png_IDAT)
   {
-      if (png_ptr->mode & PNG_AFTER_IDAT)
+      if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
         png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;

      /* If we reach an IDAT chunk, this means we have read all of the
       * header chunks, and we can start reading the image (or if this
       * is called after the image has been read - we have an error).
       */
-      if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
         png_error(png_ptr, "Missing IHDR before IDAT");

      else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-          !(png_ptr->mode & PNG_HAVE_PLTE))
+          (png_ptr->mode & PNG_HAVE_PLTE) == 0)
         png_error(png_ptr, "Missing PLTE before IDAT");

      png_ptr->mode |= PNG_HAVE_IDAT;
      png_ptr->process_mode = PNG_READ_IDAT_MODE;

-      if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+      if ((png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) == 0)
         if (png_ptr->push_length == 0)
            return;

-      if (png_ptr->mode & PNG_AFTER_IDAT)
+      if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
         png_benign_error(png_ptr, "Too many IDATs found");
   }

@@ -449,7 +449,7 @@ png_push_crc_skip(png_structrp png_ptr, png_uint_32 skip)
 void /* PRIVATE */
 png_push_crc_finish(png_structrp png_ptr)
 {
-   if (png_ptr->skip_length && png_ptr->save_buffer_size)
+   if (png_ptr->skip_length != 0 && png_ptr->save_buffer_size != 0)
   {
      png_size_t save_size = png_ptr->save_buffer_size;
      png_uint_32 skip_length = png_ptr->skip_length;
@@ -473,7 +473,7 @@ png_push_crc_finish(png_structrp png_ptr)
      png_ptr->save_buffer_size -= save_size;
      png_ptr->save_buffer_ptr += save_size;
   }
-   if (png_ptr->skip_length && png_ptr->current_buffer_size)
+   if (png_ptr->skip_length != 0 && png_ptr->current_buffer_size != 0)
   {
      png_size_t save_size = png_ptr->current_buffer_size;
      png_uint_32 skip_length = png_ptr->skip_length;
@@ -494,7 +494,7 @@ png_push_crc_finish(png_structrp png_ptr)
      png_ptr->current_buffer_size -= save_size;
      png_ptr->current_buffer_ptr += save_size;
   }
-   if (!png_ptr->skip_length)
+   if (png_ptr->skip_length == 0)
   {
      PNG_PUSH_SAVE_BUFFER_IF_LT(4)
      png_crc_finish(png_ptr, 0);
@@ -511,7 +511,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
      return;

   ptr = buffer;
-   if (png_ptr->save_buffer_size)
+   if (png_ptr->save_buffer_size != 0)
   {
      png_size_t save_size;

@@ -528,7 +528,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
      png_ptr->save_buffer_size -= save_size;
      png_ptr->save_buffer_ptr += save_size;
   }
-   if (length && png_ptr->current_buffer_size)
+   if (length != 0 && png_ptr->current_buffer_size != 0)
   {
      png_size_t save_size;

@@ -548,7 +548,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
 void /* PRIVATE */
 png_push_save_buffer(png_structrp png_ptr)
 {
-   if (png_ptr->save_buffer_size)
+   if (png_ptr->save_buffer_size != 0)
   {
      if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
      {
@@ -617,7 +617,7 @@ png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
 void /* PRIVATE */
 png_push_read_IDAT(png_structrp png_ptr)
 {
-   if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
+   if ((png_ptr->mode & PNG_HAVE_CHUNK_HEADER) == 0)
   {
      png_byte chunk_length[4];
      png_byte chunk_tag[4];
@@ -635,7 +635,7 @@ png_push_read_IDAT(png_structrp png_ptr)
      {
         png_ptr->process_mode = PNG_READ_CHUNK_MODE;

-         if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+         if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
            png_error(png_ptr, "Not enough compressed data");

         return;
@@ -644,7 +644,7 @@ png_push_read_IDAT(png_structrp png_ptr)
      png_ptr->idat_size = png_ptr->push_length;
   }

-   if (png_ptr->idat_size && png_ptr->save_buffer_size)
+   if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
   {
      png_size_t save_size = png_ptr->save_buffer_size;
      png_uint_32 idat_size = png_ptr->idat_size;
@@ -671,7 +671,7 @@ png_push_read_IDAT(png_structrp png_ptr)
      png_ptr->save_buffer_ptr += save_size;
   }

-   if (png_ptr->idat_size && png_ptr->current_buffer_size)
+   if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
   {
      png_size_t save_size = png_ptr->current_buffer_size;
      png_uint_32 idat_size = png_ptr->idat_size;
@@ -696,7 +696,7 @@ png_push_read_IDAT(png_structrp png_ptr)
      png_ptr->current_buffer_size -= save_size;
      png_ptr->current_buffer_ptr += save_size;
   }
-   if (!png_ptr->idat_size)
+   if (png_ptr->idat_size == 0)
   {
      PNG_PUSH_SAVE_BUFFER_IF_LT(4)
      png_crc_finish(png_ptr, 0);
@@ -843,7 +843,7 @@ png_push_process_row(png_structrp png_ptr)
   memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);

 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
-   if (png_ptr->transformations)
+   if (png_ptr->transformations != 0)
      png_do_read_transformations(png_ptr, &row_info);
 #endif

@@ -861,7 +861,8 @@ png_push_process_row(png_structrp png_ptr)

 #ifdef PNG_READ_INTERLACING_SUPPORTED
   /* Expand interlaced rows to full size */
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
   {
      if (png_ptr->pass < 6)
         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
@@ -1068,7 +1069,7 @@ png_read_push_finish_row(png_structrp png_ptr)
   if (png_ptr->row_number < png_ptr->num_rows)
      return;

-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
   {
      png_ptr->row_number = 0;
      memset(png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
@@ -1092,7 +1093,7 @@ png_read_push_finish_row(png_structrp png_ptr)
             png_pass_start[png_ptr->pass]) /
             png_pass_inc[png_ptr->pass];

-         if (png_ptr->transformations & PNG_INTERLACE)
+         if ((png_ptr->transformations & PNG_INTERLACE) != 0)
            break;

         png_ptr->num_rows = (png_ptr->height +
--- a/pngread.c
+++ b/pngread.c
@@ -113,20 +113,20 @@ png_read_info(png_structrp png_ptr, png_inforp info_ptr)
       */
      if (chunk_name == png_IDAT)
      {
-         if (!(png_ptr->mode & PNG_HAVE_IHDR))
+         if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
            png_chunk_error(png_ptr, "Missing IHDR before IDAT");

         else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-             !(png_ptr->mode & PNG_HAVE_PLTE))
+             (png_ptr->mode & PNG_HAVE_PLTE) == 0)
            png_chunk_error(png_ptr, "Missing PLTE before IDAT");

-         else if (png_ptr->mode & PNG_AFTER_IDAT)
+         else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
            png_chunk_benign_error(png_ptr, "Too many IDATs found");

         png_ptr->mode |= PNG_HAVE_IDAT;
      }

-      else if (png_ptr->mode & PNG_HAVE_IDAT)
+      else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
         png_ptr->mode |= PNG_AFTER_IDAT;

      /* This should be a binary subdivision search or a hash for
@@ -315,7 +315,7 @@ png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
   png_debug(1, "in png_do_read_intrapixel");

   if (
-       (row_info->color_type & PNG_COLOR_MASK_COLOR))
+       (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      int bytes_per_pixel;
      png_uint_32 row_width = row_info->width;
@@ -385,7 +385,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
   /* png_read_start_row sets the information (in particular iwidth) for this
    * interlace pass.
    */
-   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
+   if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
      png_read_start_row(png_ptr);

   /* 1.5.6: row_info moved out of png_struct to a local here. */
@@ -401,38 +401,38 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
   {
   /* Check for transforms that have been set but were defined out */
 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
-   if (png_ptr->transformations & PNG_INVERT_MONO)
+   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
      png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
 #endif

 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
-   if (png_ptr->transformations & PNG_FILLER)
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
      png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
 #endif

 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
    !defined(PNG_READ_PACKSWAP_SUPPORTED)
-   if (png_ptr->transformations & PNG_PACKSWAP)
+   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
      png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
 #endif

 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
-   if (png_ptr->transformations & PNG_PACK)
+   if ((png_ptr->transformations & PNG_PACK) != 0)
      png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
 #endif

 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
-   if (png_ptr->transformations & PNG_SHIFT)
+   if ((png_ptr->transformations & PNG_SHIFT) != 0)
      png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
 #endif

 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
-   if (png_ptr->transformations & PNG_BGR)
+   if ((png_ptr->transformations & PNG_BGR) != 0)
      png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
 #endif

 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
+   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
      png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
 #endif
   }
@@ -445,7 +445,8 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
    * untransformed) and, because of the libpng API for interlaced images, this
    * means we must transform before de-interlacing.
    */
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
   {
      switch (png_ptr->pass)
      {
@@ -516,7 +517,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)

         default:
         case 6:
-            if (!(png_ptr->row_number & 1))
+            if ((png_ptr->row_number & 1) == 0)
            {
               png_read_finish_row(png_ptr);
               return;
@@ -526,7 +527,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
   }
 #endif

-   if (!(png_ptr->mode & PNG_HAVE_IDAT))
+   if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
      png_error(png_ptr, "Invalid attempt to read row data");

   /* Fill the row with IDAT data: */
@@ -549,7 +550,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
   memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);

 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
       (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
   {
      /* Intrapixel differencing */
@@ -575,8 +576,8 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)

 #ifdef PNG_READ_INTERLACING_SUPPORTED
   /* Expand interlaced rows to full size */
-   if (png_ptr->interlaced &&
-      (png_ptr->transformations & PNG_INTERLACE))
+   if (png_ptr->interlaced != 0 &&
+      (png_ptr->transformations & PNG_INTERLACE) != 0)
   {
      if (png_ptr->pass < 6)
         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
@@ -699,7 +700,7 @@ png_read_image(png_structrp png_ptr, png_bytepp image)
      return;

 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
+   if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
   {
      pass = png_set_interlace_handling(png_ptr);
      /* And make sure transforms are initialized. */
@@ -707,7 +708,8 @@ png_read_image(png_structrp png_ptr, png_bytepp image)
   }
   else
   {
-      if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
+      if (png_ptr->interlaced != 0 &&
+          (png_ptr->transformations & PNG_INTERLACE) == 0)
      {
         /* Caller called png_start_read_image or png_read_update_info without
          * first turning on the PNG_INTERLACE transform.  We can fix this here,
@@ -767,7 +769,7 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
    * still be pending IDAT data and an owned zstream.  Deal with this here.
    */
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-   if (!png_chunk_unknown_handling(png_ptr, png_IDAT))
+   if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
 #endif
      png_read_finish_IDAT(png_ptr);

@@ -797,7 +799,8 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
      {
         if (chunk_name == png_IDAT)
         {
-            if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+            if ((length > 0) ||
+                (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
               png_benign_error(png_ptr, "Too many IDATs found");
         }
         png_handle_unknown(png_ptr, info_ptr, length, keep);
@@ -811,7 +814,8 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
         /* Zero length IDATs are legal after the last IDAT has been
          * read, but not after other chunks have been read.
          */
-         if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
+         if ((length > 0) ||
+             (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
            png_benign_error(png_ptr, "Too many IDATs found");

         png_crc_finish(png_ptr, length);
@@ -907,7 +911,7 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
      else
         png_handle_unknown(png_ptr, info_ptr, length,
            PNG_HANDLE_CHUNK_AS_DEFAULT);
-   } while (!(png_ptr->mode & PNG_HAVE_IEND));
+   } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
 }
 #endif /* PNG_SEQUENTIAL_READ_SUPPORTED */

@@ -935,7 +939,7 @@ png_read_destroy(png_structrp png_ptr)
   png_ptr->quantize_index = NULL;
 #endif

-   if (png_ptr->free_me & PNG_FREE_PLTE)
+   if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
   {
      png_zfree(png_ptr, png_ptr->palette);
      png_ptr->palette = NULL;
@@ -944,7 +948,7 @@ png_read_destroy(png_structrp png_ptr)

 #if defined(PNG_tRNS_SUPPORTED) || \
    defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
-   if (png_ptr->free_me & PNG_FREE_TRNS)
+   if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
   {
      png_free(png_ptr, png_ptr->trans_alpha);
      png_ptr->trans_alpha = NULL;
@@ -1039,7 +1043,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,

   /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
    */
-   if (transforms & PNG_TRANSFORM_SCALE_16)
+   if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
     /* Added at libpng-1.5.4. "strip_16" produces the same result that it
      * did in earlier versions, while "scale_16" is now more accurate.
      */
@@ -1053,7 +1057,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
    * latter by doing SCALE first.  This is ok and allows apps not to check for
    * which is supported to get the right answer.
    */
-   if (transforms & PNG_TRANSFORM_STRIP_16)
+   if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
      png_set_strip_16(png_ptr);
 #else
@@ -1063,7 +1067,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
   /* Strip alpha bytes from the input data without combining with
    * the background (not recommended).
    */
-   if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
+   if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
      png_set_strip_alpha(png_ptr);
 #else
@@ -1073,7 +1077,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
   /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
    * byte into separate bytes (useful for paletted and grayscale images).
    */
-   if (transforms & PNG_TRANSFORM_PACKING)
+   if ((transforms & PNG_TRANSFORM_PACKING) != 0)
 #ifdef PNG_READ_PACK_SUPPORTED
      png_set_packing(png_ptr);
 #else
@@ -1083,7 +1087,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
   /* Change the order of packed pixels to least significant bit first
    * (not useful if you are using png_set_packing).
    */
-   if (transforms & PNG_TRANSFORM_PACKSWAP)
+   if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
      png_set_packswap(png_ptr);
 #else
@@ -1095,7 +1099,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
    * Expand paletted or RGB images with transparency to full alpha
    * channels so the data will be available as RGBA quartets.
    */
-   if (transforms & PNG_TRANSFORM_EXPAND)
+   if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
 #ifdef PNG_READ_EXPAND_SUPPORTED
      png_set_expand(png_ptr);
 #else
@@ -1107,7 +1111,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,

   /* Invert monochrome files to have 0 as white and 1 as black
    */
-   if (transforms & PNG_TRANSFORM_INVERT_MONO)
+   if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
 #ifdef PNG_READ_INVERT_SUPPORTED
      png_set_invert_mono(png_ptr);
 #else
@@ -1118,16 +1122,16 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
    * [0,65535] to the original [0,7] or [0,31], or whatever range the
    * colors were originally in:
    */
-   if (transforms & PNG_TRANSFORM_SHIFT)
+   if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
 #ifdef PNG_READ_SHIFT_SUPPORTED
-      if (info_ptr->valid & PNG_INFO_sBIT)
+      if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
         png_set_shift(png_ptr, &info_ptr->sig_bit);
 #else
      png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
 #endif

   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
-   if (transforms & PNG_TRANSFORM_BGR)
+   if ((transforms & PNG_TRANSFORM_BGR) != 0)
 #ifdef PNG_READ_BGR_SUPPORTED
      png_set_bgr(png_ptr);
 #else
@@ -1135,7 +1139,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
-   if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
+   if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
      png_set_swap_alpha(png_ptr);
 #else
@@ -1143,7 +1147,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

   /* Swap bytes of 16-bit files to least significant byte first */
-   if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
+   if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
 #ifdef PNG_READ_SWAP_SUPPORTED
      png_set_swap(png_ptr);
 #else
@@ -1152,7 +1156,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,

 /* Added at libpng-1.2.41 */
   /* Invert the alpha channel from opacity to transparency */
-   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
+   if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
      png_set_invert_alpha(png_ptr);
 #else
@@ -1161,7 +1165,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,

 /* Added at libpng-1.2.41 */
   /* Expand grayscale image to RGB */
-   if (transforms & PNG_TRANSFORM_GRAY_TO_RGB)
+   if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
      png_set_gray_to_rgb(png_ptr);
 #else
@@ -1169,7 +1173,7 @@ png_read_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

 /* Added at libpng-1.5.4 */
-   if (transforms & PNG_TRANSFORM_EXPAND_16)
+   if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
 #ifdef PNG_READ_EXPAND_16_SUPPORTED
      png_set_expand_16(png_ptr);
 #else
@@ -1327,10 +1331,10 @@ png_image_format(png_structrp png_ptr)
 {
   png_uint_32 format = 0;

-   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
      format |= PNG_FORMAT_FLAG_COLOR;

-   if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      format |= PNG_FORMAT_FLAG_ALPHA;

   /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
@@ -1344,7 +1348,7 @@ png_image_format(png_structrp png_ptr)
   if (png_ptr->bit_depth == 16)
      format |= PNG_FORMAT_FLAG_LINEAR;

-   if (png_ptr->color_type & PNG_COLOR_MASK_PALETTE)
+   if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
      format |= PNG_FORMAT_FLAG_COLORMAP;

   return format;
@@ -1444,7 +1448,7 @@ png_image_begin_read_from_stdio(png_imagep image, FILE* file)
   {
      if (file != NULL)
      {
-         if (png_image_read_init(image))
+         if (png_image_read_init(image) != 0)
         {
            /* This is slightly evil, but png_init_io doesn't do anything other
             * than this and we haven't changed the standard IO functions so
@@ -1478,7 +1482,7 @@ png_image_begin_read_from_file(png_imagep image, const char *file_name)

         if (fp != NULL)
         {
-            if (png_image_read_init(image))
+            if (png_image_read_init(image) != 0)
            {
               image->opaque->png_ptr->io_ptr = fp;
               image->opaque->owned_file = 1;
@@ -1543,7 +1547,7 @@ int PNGAPI png_image_begin_read_from_memory(png_imagep image,
   {
      if (memory != NULL && size > 0)
      {
-         if (png_image_read_init(image))
+         if (png_image_read_init(image) != 0)
         {
            /* Now set the IO functions to read from the memory buffer and
             * store it into io_ptr.  Again do this in-place to avoid calling a
@@ -1635,9 +1639,9 @@ static void
 set_file_encoding(png_image_read_control *display)
 {
   png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
-   if (png_gamma_significant(g))
+   if (png_gamma_significant(g) != 0)
   {
-      if (png_gamma_not_sRGB(g))
+      if (png_gamma_not_sRGB(g) != 0)
      {
         display->file_encoding = P_FILE;
         display->gamma_to_linear = png_reciprocal(g);
@@ -1732,7 +1736,7 @@ png_create_colormap_entry(png_image_read_control *display,
   png_uint_32 alpha, int encoding)
 {
   png_imagep image = display->image;
-   const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) ?
+   const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
      P_LINEAR : P_sRGB;
   const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
      (red != green || green != blue);
@@ -1762,7 +1766,7 @@ png_create_colormap_entry(png_image_read_control *display,
      green = png_gamma_16bit_correct(green*257, g);
      blue = png_gamma_16bit_correct(blue*257, g);

-      if (convert_to_Y || output_encoding == P_LINEAR)
+      if (convert_to_Y != 0 || output_encoding == P_LINEAR)
      {
         alpha *= 257;
         encoding = P_LINEAR;
@@ -1789,7 +1793,8 @@ png_create_colormap_entry(png_image_read_control *display,
      encoding = P_LINEAR;
   }

-   else if (encoding == P_sRGB && (convert_to_Y || output_encoding == P_LINEAR))
+   else if (encoding == P_sRGB &&
+       (convert_to_Y  != 0 || output_encoding == P_LINEAR))
   {
      /* The values are 8-bit sRGB values, but must be converted to 16-bit
       * linear.
@@ -1847,7 +1852,7 @@ png_create_colormap_entry(png_image_read_control *display,
 #        define afirst 0
 #     endif
 #     ifdef PNG_FORMAT_BGR_SUPPORTED
-         const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
+         const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
 #     else
 #        define bgr 0
 #     endif
@@ -2059,7 +2064,7 @@ png_image_read_colormap(png_voidp argument)

   const png_structrp png_ptr = image->opaque->png_ptr;
   const png_uint_32 output_format = image->format;
-   const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) ?
+   const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
      P_LINEAR : P_sRGB;

   unsigned int cmap_entries;
@@ -2098,7 +2103,7 @@ png_image_read_colormap(png_voidp argument)
      else
      {
         back_g = display->background->green;
-         if (output_format & PNG_FORMAT_FLAG_COLOR)
+         if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
         {
            back_r = display->background->red;
            back_b = display->background->blue;
@@ -2240,7 +2245,7 @@ png_image_read_colormap(png_voidp argument)
            {
               unsigned int back_alpha;

-               if (output_format & PNG_FORMAT_FLAG_ALPHA)
+               if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
                  back_alpha = 0;

               else
@@ -2321,7 +2326,7 @@ png_image_read_colormap(png_voidp argument)
          */
         data_encoding = P_sRGB;

-         if (output_format & PNG_FORMAT_FLAG_ALPHA)
+         if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
         {
            if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
               png_error(png_ptr, "gray+alpha color-map: too few entries");
@@ -2516,7 +2521,7 @@ png_image_read_colormap(png_voidp argument)
                */
               if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
                  png_ptr->num_trans > 0) &&
-                  png_gamma_not_sRGB(png_ptr->colorspace.gamma))
+                  png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
               {
                  cmap_entries = make_gray_file_colormap(display);
                  data_encoding = P_FILE;
@@ -2604,7 +2609,7 @@ png_image_read_colormap(png_voidp argument)
               /* Is there alpha in the output too?  If so all four channels are
                * processed into a special RGB cube with alpha support.
                */
-               if (output_format & PNG_FORMAT_FLAG_ALPHA)
+               if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
               {
                  png_uint_32 r;

@@ -2778,7 +2783,7 @@ png_image_read_colormap(png_voidp argument)

            for (i=0; i < cmap_entries; ++i)
            {
-               if (do_background && i < num_trans && trans[i] < 255)
+               if (do_background != 0 && i < num_trans && trans[i] < 255)
               {
                  if (trans[i] == 0)
                     png_create_colormap_entry(display, i, back_r, back_g,
@@ -2823,8 +2828,8 @@ png_image_read_colormap(png_voidp argument)
   }

   /* Now deal with the output processing */
-   if (expand_tRNS && png_ptr->num_trans > 0 &&
-      (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
+   if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
+       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
      png_set_tRNS_to_alpha(png_ptr);

   switch (data_encoding)
@@ -3240,7 +3245,8 @@ png_image_read_composite(png_voidp argument)
      png_uint_32  height = image->height;
      png_uint_32  width = image->width;
      ptrdiff_t    step_row = display->row_bytes;
-      unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
+      unsigned int channels =
+         (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
      int pass;

      for (pass = 0; pass < passes; ++pass)
@@ -3538,7 +3544,8 @@ png_image_read_background(png_voidp argument)
            int swap_alpha = 0;

 #           ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
-               if (preserve_alpha && (image->format & PNG_FORMAT_FLAG_AFIRST))
+               if (preserve_alpha != 0 &&
+                   (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
                  swap_alpha = 1;
 #           endif

@@ -3647,10 +3654,10 @@ png_image_read_direct(png_voidp argument)
      int mode; /* alpha mode */

      /* Do this first so that we have a record if rgb to gray is happening. */
-      if (change & PNG_FORMAT_FLAG_COLOR)
+      if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
      {
         /* gray<->color transformation required. */
-         if (format & PNG_FORMAT_FLAG_COLOR)
+         if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
            png_set_gray_to_rgb(png_ptr);

         else
@@ -3668,7 +3675,7 @@ png_image_read_direct(png_voidp argument)
             * enormous change) 'do_local_background' is used to indicate that
             * the problem exists.
             */
-            if (base_format & PNG_FORMAT_FLAG_ALPHA)
+            if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
               do_local_background = 1/*maybe*/;

            png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
@@ -3683,8 +3690,8 @@ png_image_read_direct(png_voidp argument)
      {
         png_fixed_point input_gamma_default;

-         if ((base_format & PNG_FORMAT_FLAG_LINEAR) &&
-            (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
+         if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
+             (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
            input_gamma_default = PNG_GAMMA_LINEAR;
         else
            input_gamma_default = PNG_DEFAULT_sRGB;
@@ -3700,7 +3707,7 @@ png_image_read_direct(png_voidp argument)
         /* If there *is* an alpha channel in the input it must be multiplied
          * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
          */
-         if (base_format & PNG_FORMAT_FLAG_ALPHA)
+         if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
            mode = PNG_ALPHA_STANDARD; /* associated alpha */

         else
@@ -3731,7 +3738,7 @@ png_image_read_direct(png_voidp argument)
          * final value.
          */
         if (png_muldiv(&gtest, output_gamma, png_ptr->colorspace.gamma,
-               PNG_FP_1) && !png_gamma_significant(gtest))
+               PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
            do_local_background = 0;

         else if (mode == PNG_ALPHA_STANDARD)
@@ -3744,9 +3751,9 @@ png_image_read_direct(png_voidp argument)
      }

      /* If the bit-depth changes then handle that here. */
-      if (change & PNG_FORMAT_FLAG_LINEAR)
+      if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
      {
-         if (linear /*16-bit output*/)
+         if (linear != 0 /*16-bit output*/)
            png_set_expand_16(png_ptr);

         else /* 8-bit output */
@@ -3756,13 +3763,13 @@ png_image_read_direct(png_voidp argument)
      }

      /* Now the background/alpha channel changes. */
-      if (change & PNG_FORMAT_FLAG_ALPHA)
+      if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
      {
         /* Removing an alpha channel requires composition for the 8-bit
          * formats; for the 16-bit it is already done, above, by the
          * pre-multiplication and the channel just needs to be stripped.
          */
-         if (base_format & PNG_FORMAT_FLAG_ALPHA)
+         if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
         {
            /* If RGB->gray is happening the alpha channel must be left and the
             * operation completed locally.
@@ -3827,7 +3834,7 @@ png_image_read_direct(png_voidp argument)
               filler = 255;

 #           ifdef PNG_FORMAT_AFIRST_SUPPORTED
-               if (format & PNG_FORMAT_FLAG_AFIRST)
+               if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
               {
                  where = PNG_FILLER_BEFORE;
                  change &= ~PNG_FORMAT_FLAG_AFIRST;
@@ -3851,12 +3858,12 @@ png_image_read_direct(png_voidp argument)
      png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);

 #     ifdef PNG_FORMAT_BGR_SUPPORTED
-         if (change & PNG_FORMAT_FLAG_BGR)
+         if ((change & PNG_FORMAT_FLAG_BGR) != 0)
         {
            /* Check only the output format; PNG is never BGR; don't do this if
             * the output is gray, but fix up the 'format' value in that case.
             */
-            if (format & PNG_FORMAT_FLAG_COLOR)
+            if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
               png_set_bgr(png_ptr);

            else
@@ -3867,14 +3874,14 @@ png_image_read_direct(png_voidp argument)
 #     endif

 #     ifdef PNG_FORMAT_AFIRST_SUPPORTED
-         if (change & PNG_FORMAT_FLAG_AFIRST)
+         if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
         {
            /* Only relevant if there is an alpha channel - it's particularly
             * important to handle this correctly because do_local_compose may
             * be set above and then libpng will keep the alpha channel for this
             * code to remove.
             */
-            if (format & PNG_FORMAT_FLAG_ALPHA)
+            if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
            {
               /* Disable this if doing a local background,
                * TODO: remove this when local background is no longer required.
@@ -3897,7 +3904,7 @@ png_image_read_direct(png_voidp argument)
      {
         PNG_CONST png_uint_16 le = 0x0001;

-         if (*(png_const_bytep)&le)
+         if ((*(png_const_bytep) & le) != 0)
            png_set_swap(png_ptr);
      }

@@ -3922,10 +3929,10 @@ png_image_read_direct(png_voidp argument)
   {
      png_uint_32 info_format = 0;

-      if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
+      if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
         info_format |= PNG_FORMAT_FLAG_COLOR;

-      if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+      if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      {
         /* do_local_compose removes this channel below. */
         if (do_local_compose == 0)
@@ -3944,14 +3951,14 @@ png_image_read_direct(png_voidp argument)
         info_format |= PNG_FORMAT_FLAG_LINEAR;

 #     ifdef PNG_FORMAT_BGR_SUPPORTED
-         if (png_ptr->transformations & PNG_BGR)
+         if ((png_ptr->transformations & PNG_BGR) != 0)
            info_format |= PNG_FORMAT_FLAG_BGR;
 #     endif

 #     ifdef PNG_FORMAT_AFIRST_SUPPORTED
         if (do_local_background == 2)
         {
-            if (format & PNG_FORMAT_FLAG_AFIRST)
+            if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
               info_format |= PNG_FORMAT_FLAG_AFIRST;
         }

@@ -4080,7 +4087,7 @@ png_image_finish_read(png_imagep image, png_const_colorp background,
            /* Choose the correct 'end' routine; for the color-map case all the
             * setup has already been done.
             */
-            if (image->format & PNG_FORMAT_FLAG_COLORMAP)
+            if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
               result =
                  png_safe_execute(image, png_image_read_colormap, &display) &&
                  png_safe_execute(image, png_image_read_colormapped, &display);
--- 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 1.6.11 [June 5, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -98,7 +98,7 @@ png_rtran_ok(png_structrp png_ptr, int need_IHDR)
 {
   if (png_ptr != NULL)
   {
-      if (png_ptr->flags & PNG_FLAG_ROW_INIT)
+      if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
         png_app_error(png_ptr,
            "invalid after png_start_read_image or png_read_update_info");

@@ -127,7 +127,7 @@ png_set_background_fixed(png_structrp png_ptr,
 {
   png_debug(1, "in png_set_background_fixed");

-   if (!png_rtran_ok(png_ptr, 0) || background_color == NULL)
+   if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
      return;

   if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
@@ -171,7 +171,7 @@ png_set_scale_16(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_scale_16");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= PNG_SCALE_16_TO_8;
@@ -185,7 +185,7 @@ png_set_strip_16(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_strip_16");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= PNG_16_TO_8;
@@ -198,7 +198,7 @@ png_set_strip_alpha(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_strip_alpha");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= PNG_STRIP_ALPHA;
@@ -279,7 +279,7 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,

   png_debug(1, "in png_set_alpha_mode");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
@@ -371,7 +371,7 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
      png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
      png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;

-      if (png_ptr->transformations & PNG_COMPOSE)
+      if ((png_ptr->transformations & PNG_COMPOSE) != 0)
         png_error(png_ptr,
            "conflicting calls to set alpha mode and background");

@@ -415,7 +415,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
 {
   png_debug(1, "in png_set_quantize");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= PNG_QUANTIZE;
@@ -802,7 +802,7 @@ png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
 {
   png_debug(1, "in png_set_gamma_fixed");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   /* New in libpng-1.5.4 - reserve particular negative values as flags. */
@@ -855,7 +855,7 @@ png_set_expand(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_expand");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
@@ -885,7 +885,7 @@ png_set_palette_to_rgb(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_palette_to_rgb");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
@@ -897,7 +897,7 @@ png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_expand_gray_1_2_4_to_8");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= PNG_EXPAND;
@@ -909,7 +909,7 @@ png_set_tRNS_to_alpha(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_tRNS_to_alpha");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
@@ -925,7 +925,7 @@ png_set_expand_16(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_expand_16");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
@@ -938,7 +938,7 @@ png_set_gray_to_rgb(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_gray_to_rgb");

-   if (!png_rtran_ok(png_ptr, 0))
+   if (png_rtran_ok(png_ptr, 0) == 0)
      return;

   /* Because rgb must be 8 bits or more: */
@@ -956,7 +956,7 @@ png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action,

   /* Need the IHDR here because of the check on color_type below. */
   /* TODO: fix this */
-   if (!png_rtran_ok(png_ptr, 1))
+   if (png_rtran_ok(png_ptr, 1) == 0)
      return;

   switch (error_action)
@@ -1153,8 +1153,8 @@ png_init_palette_transformations(png_structrp png_ptr)
   /* The following code cannot be entered in the alpha pre-multiplication case
    * because PNG_BACKGROUND_EXPAND is cancelled below.
    */
-   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-       (png_ptr->transformations & PNG_EXPAND))
+   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
+       (png_ptr->transformations & PNG_EXPAND) != 0)
   {
      {
         png_ptr->background.red   =
@@ -1165,9 +1165,9 @@ png_init_palette_transformations(png_structrp png_ptr)
             png_ptr->palette[png_ptr->background.index].blue;

 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-        if (png_ptr->transformations & PNG_INVERT_ALPHA)
+        if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
        {
-           if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
+           if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
           {
              /* Invert the alpha channel (in tRNS) unless the pixels are
               * going to be expanded, in which case leave it for later
@@ -1220,9 +1220,9 @@ png_init_rgb_transformations(png_structrp png_ptr)
   /* The following code cannot be entered in the alpha pre-multiplication case
    * because PNG_BACKGROUND_EXPAND is cancelled below.
    */
-   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-       (png_ptr->transformations & PNG_EXPAND) &&
-       !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
+       (png_ptr->transformations & PNG_EXPAND) != 0 &&
+       (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
       /* i.e., GRAY or GRAY_ALPHA */
   {
      {
@@ -1260,7 +1260,7 @@ png_init_rgb_transformations(png_structrp png_ptr)
         png_ptr->background.red = png_ptr->background.green =
            png_ptr->background.blue = (png_uint_16)gray;

-         if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
+         if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
         {
            png_ptr->trans_color.red = png_ptr->trans_color.green =
               png_ptr->trans_color.blue = (png_uint_16)trans_gray;
@@ -1374,8 +1374,8 @@ png_init_read_transformations(png_structrp png_ptr)
    * 23) PNG_USER_TRANSFORM [must be last]
    */
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
-      !(png_ptr->transformations & PNG_COMPOSE))
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) == 0)
   {
      /* Stripping the alpha channel happens immediately after the 'expand'
       * transformations, before all other transformation, so it cancels out
@@ -1401,7 +1401,7 @@ png_init_read_transformations(png_structrp png_ptr)
   /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
    * settings will have no effect.
    */
-   if (!png_gamma_significant(png_ptr->screen_gamma))
+   if (png_gamma_significant(png_ptr->screen_gamma) == 0)
   {
      png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
      png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
@@ -1412,7 +1412,7 @@ png_init_read_transformations(png_structrp png_ptr)
   /* Make sure the coefficients for the rgb to gray conversion are set
    * appropriately.
    */
-   if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
      png_colorspace_set_rgb_coefficients(png_ptr);
 #endif

@@ -1433,23 +1433,23 @@ png_init_read_transformations(png_structrp png_ptr)
    * png_set_background, along with the bit depth, then the code has a record
    * of exactly what color space the background is currently in.
    */
-   if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
+   if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
   {
      /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
       * the file was grayscale the background value is gray.
       */
-      if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+      if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
         png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
   }

-   else if (png_ptr->transformations & PNG_COMPOSE)
+   else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
   {
      /* PNG_COMPOSE: png_set_background was called with need_expand false,
       * so the color is in the color space of the output or png_set_alpha_mode
       * was called and the color is black.  Ignore RGB_TO_GRAY because that
       * happens before GRAY_TO_RGB.
       */
-      if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+      if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
      {
         if (png_ptr->background.red == png_ptr->background.green &&
             png_ptr->background.red == png_ptr->background.blue)
@@ -1481,10 +1481,10 @@ png_init_read_transformations(png_structrp png_ptr)

 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
   defined(PNG_READ_EXPAND_16_SUPPORTED)
-   if ((png_ptr->transformations & PNG_EXPAND_16) &&
-      (png_ptr->transformations & PNG_COMPOSE) &&
-      !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-      png_ptr->bit_depth != 16)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
+       png_ptr->bit_depth != 16)
   {
      /* TODO: fix this.  Because the expand_16 operation is after the compose
       * handling the background color must be 8, not 16, bits deep, but the
@@ -1508,10 +1508,10 @@ png_init_read_transformations(png_structrp png_ptr)
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
   (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
   defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
-   if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
-      (png_ptr->transformations & PNG_COMPOSE) &&
-      !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
-      png_ptr->bit_depth == 16)
+   if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
+       png_ptr->bit_depth == 16)
   {
      /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
       * component this will also happen after PNG_COMPOSE and so the background
@@ -1554,25 +1554,24 @@ png_init_read_transformations(png_structrp png_ptr)
    * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
    * tables.
    */
-   if ((png_ptr->transformations & PNG_GAMMA)
-      || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
-         && (png_gamma_significant(png_ptr->colorspace.gamma) ||
-            png_gamma_significant(png_ptr->screen_gamma)))
-      || ((png_ptr->transformations & PNG_COMPOSE)
-         && (png_gamma_significant(png_ptr->colorspace.gamma)
-            || png_gamma_significant(png_ptr->screen_gamma)
+   if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
+       ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
+        (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
+         png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
+        ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
+         (png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
+          png_gamma_significant(png_ptr->screen_gamma) != 0
 #  ifdef PNG_READ_BACKGROUND_SUPPORTED
-            || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
-               && png_gamma_significant(png_ptr->background_gamma))
+         || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
+           png_gamma_significant(png_ptr->background_gamma) != 0)
 #  endif
-      )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
-         && png_gamma_significant(png_ptr->screen_gamma))
-      )
+        )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
+       png_gamma_significant(png_ptr->screen_gamma) != 0))
   {
      png_build_gamma_table(png_ptr, png_ptr->bit_depth);

 #ifdef PNG_READ_BACKGROUND_SUPPORTED
-      if (png_ptr->transformations & PNG_COMPOSE)
+      if ((png_ptr->transformations & PNG_COMPOSE) != 0)
      {
         /* Issue a warning about this combination: because RGB_TO_GRAY is
          * optimized to do the gamma transform if present yet do_background has
@@ -1580,11 +1579,11 @@ png_init_read_transformations(png_structrp png_ptr)
          * double-gamma-correction happens.  This is true in all versions of
          * libpng to date.
          */
-         if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+         if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
            png_warning(png_ptr,
               "libpng does not support gamma+background+rgb_to_gray");

-         if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+         if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
         {
            /* We don't get to here unless there is a tRNS chunk with non-opaque
             * entries - see the checking code at the start of this function.
@@ -1632,7 +1631,7 @@ png_init_read_transformations(png_structrp png_ptr)
                     break;
               }

-               if (png_gamma_significant(gs))
+               if (png_gamma_significant(gs) != 0)
               {
                  back.red = png_gamma_8bit_correct(png_ptr->background.red,
                      gs);
@@ -1649,7 +1648,7 @@ png_init_read_transformations(png_structrp png_ptr)
                  back.blue  = (png_byte)png_ptr->background.blue;
               }

-               if (png_gamma_significant(g))
+               if (png_gamma_significant(g) != 0)
               {
                  back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
                     g);
@@ -1832,7 +1831,7 @@ png_init_read_transformations(png_structrp png_ptr)

 #ifdef PNG_READ_BACKGROUND_SUPPORTED
   /* No GAMMA transformation (see the hanging else 4 lines above) */
-   if ((png_ptr->transformations & PNG_COMPOSE) &&
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
       (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
   {
      int i;
@@ -1870,8 +1869,8 @@ png_init_read_transformations(png_structrp png_ptr)
 #endif /* PNG_READ_BACKGROUND_SUPPORTED */

 #ifdef PNG_READ_SHIFT_SUPPORTED
-   if ((png_ptr->transformations & PNG_SHIFT) &&
-      !(png_ptr->transformations & PNG_EXPAND) &&
+   if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
+       (png_ptr->transformations & PNG_EXPAND) == 0 &&
       (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
   {
      int i;
@@ -1926,7 +1925,7 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
   png_debug(1, "in png_read_transform_info");

 #ifdef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND)
+   if ((png_ptr->transformations & PNG_EXPAND) != 0)
   {
      if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
@@ -1948,9 +1947,9 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
      }
      else
      {
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
         {
-            if (png_ptr->transformations & PNG_EXPAND_tRNS)
+            if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
               info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
         }
         if (info_ptr->bit_depth < 8)
@@ -1966,7 +1965,7 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
   /* The following is almost certainly wrong unless the background value is in
    * the screen space!
    */
-   if (png_ptr->transformations & PNG_COMPOSE)
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0)
      info_ptr->background = png_ptr->background;
 #endif

@@ -1987,12 +1986,12 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
   {
 #  ifdef PNG_READ_16BIT_SUPPORTED
 #     ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-         if (png_ptr->transformations & PNG_SCALE_16_TO_8)
+         if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
            info_ptr->bit_depth = 8;
 #     endif

 #     ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-         if (png_ptr->transformations & PNG_16_TO_8)
+         if ((png_ptr->transformations & PNG_16_TO_8) != 0)
            info_ptr->bit_depth = 8;
 #     endif

@@ -2022,23 +2021,23 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
   }

 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-   if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
      info_ptr->color_type = (png_byte)(info_ptr->color_type |
         PNG_COLOR_MASK_COLOR);
 #endif

 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-   if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
      info_ptr->color_type = (png_byte)(info_ptr->color_type &
         ~PNG_COLOR_MASK_COLOR);
 #endif

 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-   if (png_ptr->transformations & PNG_QUANTIZE)
+   if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
   {
      if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
          (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
-          png_ptr->palette_lookup && info_ptr->bit_depth == 8)
+          png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8)
      {
         info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
      }
@@ -2046,29 +2045,31 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
 #endif

 #ifdef PNG_READ_EXPAND_16_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
-      info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
+       info_ptr->bit_depth == 8 &&
+       info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
   {
      info_ptr->bit_depth = 16;
   }
 #endif

 #ifdef PNG_READ_PACK_SUPPORTED
-   if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
+   if ((png_ptr->transformations & PNG_PACK) != 0 &&
+       (info_ptr->bit_depth < 8))
      info_ptr->bit_depth = 8;
 #endif

   if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      info_ptr->channels = 1;

-   else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
      info_ptr->channels = 3;

   else
      info_ptr->channels = 1;

 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_STRIP_ALPHA)
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0)
   {
      info_ptr->color_type = (png_byte)(info_ptr->color_type &
         ~PNG_COLOR_MASK_ALPHA);
@@ -2076,25 +2077,25 @@ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
   }
 #endif

-   if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      info_ptr->channels++;

 #ifdef PNG_READ_FILLER_SUPPORTED
   /* STRIP_ALPHA and FILLER allowed:  MASK_ALPHA bit stripped above */
-   if ((png_ptr->transformations & PNG_FILLER) &&
-       ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
-       (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
+   if ((png_ptr->transformations & PNG_FILLER) != 0 &&
+       (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
+       info_ptr->color_type == PNG_COLOR_TYPE_GRAY))
   {
      info_ptr->channels++;
      /* If adding a true alpha channel not just filler */
-      if (png_ptr->transformations & PNG_ADD_ALPHA)
+      if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0)
         info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
   }
 #endif

 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
   {
      if (info_ptr->bit_depth < png_ptr->user_transform_depth)
         info_ptr->bit_depth = png_ptr->user_transform_depth;
@@ -2245,7 +2246,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
      int channels = 0;
      int bit_depth = row_info->bit_depth;

-      if (color_type & PNG_COLOR_MASK_COLOR)
+      if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
      {
         shift[channels++] = bit_depth - sig_bits->red;
         shift[channels++] = bit_depth - sig_bits->green;
@@ -2257,7 +2258,7 @@ png_do_unshift(png_row_infop row_info, png_bytep row,
         shift[channels++] = bit_depth - sig_bits->gray;
      }

-      if (color_type & PNG_COLOR_MASK_ALPHA)
+      if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
      {
         shift[channels++] = bit_depth - sig_bits->alpha;
      }
@@ -2671,7 +2672,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
   {
      if (row_info->bit_depth == 8)
      {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from G to GX */
            png_bytep sp = row + (png_size_t)row_width;
@@ -2706,7 +2707,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
 #ifdef PNG_READ_16BIT_SUPPORTED
      else if (row_info->bit_depth == 16)
      {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from GG to GGXX */
            png_bytep sp = row + (png_size_t)row_width * 2;
@@ -2748,7 +2749,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
   {
      if (row_info->bit_depth == 8)
      {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from RGB to RGBX */
            png_bytep sp = row + (png_size_t)row_width * 3;
@@ -2787,7 +2788,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
 #ifdef PNG_READ_16BIT_SUPPORTED
      else if (row_info->bit_depth == 16)
      {
-         if (flags & PNG_FLAG_FILLER_AFTER)
+         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from RRGGBB to RRGGBBXX */
            png_bytep sp = row + (png_size_t)row_width * 6;
@@ -2848,7 +2849,7 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
   png_debug(1, "in png_do_gray_to_rgb");

   if (row_info->bit_depth >= 8 &&
-       !(row_info->color_type & PNG_COLOR_MASK_COLOR))
+       (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0)
   {
      if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
      {
@@ -2986,8 +2987,8 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)

   png_debug(1, "in png_do_rgb_to_gray");

-   if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
-       (row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
+       (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
      PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
@@ -3086,15 +3087,15 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
            {
               png_uint_16 red, green, blue, w;

-               red   = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               blue  = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+               red   = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               green = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               blue  = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;

               if (red == green && red == blue)
               {
                  if (png_ptr->gamma_16_table != NULL)
-                     w = png_ptr->gamma_16_table[(red&0xff)
-                         >> png_ptr->gamma_shift][red>>8];
+                     w = png_ptr->gamma_16_table[(red & 0xff)
+                         >> png_ptr->gamma_shift][red >> 8];

                  else
                     w = red;
@@ -3137,9 +3138,9 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
            {
               png_uint_16 red, green, blue, gray16;

-               red   = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
-               blue  = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
+               red   = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               green = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
+               blue  = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;

               if (red != green || red != blue)
                  rgb_error |= 1;
@@ -3150,7 +3151,7 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
                */
               gray16  = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
                  15);
-               *(dp++) = (png_byte)((gray16>>8) & 0xff);
+               *(dp++) = (png_byte)((gray16 >> 8) & 0xff);
               *(dp++) = (png_byte)(gray16 & 0xff);

               if (have_alpha != 0)
@@ -4127,7 +4128,7 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)

   png_debug(1, "in png_do_encode_alpha");

-   if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
   {
      if (row_info->bit_depth == 8)
      {
@@ -4353,7 +4354,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
   {
      if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
      {
-         unsigned int gray = trans_color ? trans_color->gray : 0;
+         unsigned int gray = trans_color != NULL ? trans_color->gray : 0;

         if (row_info->bit_depth < 8)
         {
@@ -4497,7 +4498,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
               row_width);
         }
      }
-      else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color)
+      else if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
+          trans_color != NULL)
      {
         if (row_info->bit_depth == 8)
         {
@@ -4715,7 +4717,7 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
    * demand, if necessary.
    */
   if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
-      !(png_ptr->flags & PNG_FLAG_ROW_INIT))
+       (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
   {
      /* Application has failed to call either png_read_start_image() or
       * png_read_update_info() after setting transforms that expand pixels.
@@ -4725,7 +4727,7 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
   }

 #ifdef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND)
+   if ((png_ptr->transformations & PNG_EXPAND) != 0)
   {
      if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
      {
@@ -4735,8 +4737,8 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)

      else
      {
-         if (png_ptr->num_trans &&
-             (png_ptr->transformations & PNG_EXPAND_tRNS))
+         if (png_ptr->num_trans != 0 &&
+             (png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
            png_do_expand(row_info, png_ptr->row_buf + 1,
                &(png_ptr->trans_color));

@@ -4748,16 +4750,16 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
 #endif

 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
-      !(png_ptr->transformations & PNG_COMPOSE) &&
-      (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
-      row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) == 0 &&
+       (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+       row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
         0 /* at_start == false, because SWAP_ALPHA happens later */);
 #endif

 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-   if (png_ptr->transformations & PNG_RGB_TO_GRAY)
+   if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
   {
      int rgb_error =
          png_do_rgb_to_gray(png_ptr, row_info,
@@ -4812,22 +4814,22 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
   /* If gray -> RGB, do so now only if background is non-gray; else do later
    * for performance reasons
    */
-   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
-       !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
+       (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
      png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
 #endif

 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
   defined(PNG_READ_ALPHA_MODE_SUPPORTED)
-   if (png_ptr->transformations & PNG_COMPOSE)
+   if ((png_ptr->transformations & PNG_COMPOSE) != 0)
      png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
 #endif

 #ifdef PNG_READ_GAMMA_SUPPORTED
-   if ((png_ptr->transformations & PNG_GAMMA) &&
+   if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
      /* Because RGB_TO_GRAY does the gamma transform. */
-      !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
+      (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
 #endif
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
   defined(PNG_READ_ALPHA_MODE_SUPPORTED)
@@ -4836,7 +4838,7 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
       */
       !((png_ptr->transformations & PNG_COMPOSE) &&
       ((png_ptr->num_trans != 0) ||
-       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
+       (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
 #endif
      /* Because png_init_read_transformations transforms the palette, unless
       * RGB_TO_GRAY will do the transform.
@@ -4846,22 +4848,22 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
 #endif

 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
-   if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
-      (png_ptr->transformations & PNG_COMPOSE) &&
-      (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
-      row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+   if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
+       (png_ptr->transformations & PNG_COMPOSE) != 0 &&
+       (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
+       row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-         0 /* at_start == false, because SWAP_ALPHA happens later */);
+          0 /* at_start == false, because SWAP_ALPHA happens later */);
 #endif

 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
-   if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
-      (row_info->color_type & PNG_COLOR_MASK_ALPHA))
+   if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
+       (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
 #endif

 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-   if (png_ptr->transformations & PNG_SCALE_16_TO_8)
+   if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
      png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
 #endif

@@ -4870,12 +4872,12 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
    * by putting the 'scale' option first if the app asks for scale (either by
    * calling the API or in a TRANSFORM flag) this is what happens.
    */
-   if (png_ptr->transformations & PNG_16_TO_8)
+   if ((png_ptr->transformations & PNG_16_TO_8) != 0)
      png_do_chop(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-   if (png_ptr->transformations & PNG_QUANTIZE)
+   if ((png_ptr->transformations & PNG_QUANTIZE) != 0)
   {
      png_do_quantize(row_info, png_ptr->row_buf + 1,
          png_ptr->palette_lookup, png_ptr->quantize_index);
@@ -4891,35 +4893,35 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
    * is efficient (particularly true in the case of gamma correction, where
    * better accuracy results faster!)
    */
-   if (png_ptr->transformations & PNG_EXPAND_16)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
      png_do_expand_16(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
   /* NOTE: moved here in 1.5.4 (from much later in this list.) */
-   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
-       (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
+       (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0)
      png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_INVERT_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_MONO)
+   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
      png_do_invert(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_ALPHA)
+   if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
      png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_SHIFT_SUPPORTED
-   if (png_ptr->transformations & PNG_SHIFT)
+   if ((png_ptr->transformations & PNG_SHIFT) != 0)
      png_do_unshift(row_info, png_ptr->row_buf + 1,
          &(png_ptr->shift));
 #endif

 #ifdef PNG_READ_PACK_SUPPORTED
-   if (png_ptr->transformations & PNG_PACK)
+   if ((png_ptr->transformations & PNG_PACK) != 0)
      png_do_unpack(row_info, png_ptr->row_buf + 1);
 #endif

@@ -4931,35 +4933,35 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
 #endif

 #ifdef PNG_READ_BGR_SUPPORTED
-   if (png_ptr->transformations & PNG_BGR)
+   if ((png_ptr->transformations & PNG_BGR) != 0)
      png_do_bgr(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_PACKSWAP)
+   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
      png_do_packswap(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_FILLER_SUPPORTED
-   if (png_ptr->transformations & PNG_FILLER)
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
      png_do_read_filler(row_info, png_ptr->row_buf + 1,
          (png_uint_32)png_ptr->filler, png_ptr->flags);
 #endif

 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_ALPHA)
+   if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
      png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_READ_16BIT_SUPPORTED
 #ifdef PNG_READ_SWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
+   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
      png_do_swap(row_info, png_ptr->row_buf + 1);
 #endif
 #endif

 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
    {
      if (png_ptr->read_user_transform_fn != NULL)
         (*(png_ptr->read_user_transform_fn)) /* User read transform function */
@@ -4973,10 +4975,10 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
             png_ptr->row_buf + 1);    /* start of pixel data for row */
 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
-      if (png_ptr->user_transform_depth)
+      if (png_ptr->user_transform_depth != 0)
         row_info->bit_depth = png_ptr->user_transform_depth;

-      if (png_ptr->user_transform_channels)
+      if (png_ptr->user_transform_channels != 0)
         row_info->channels = png_ptr->user_transform_channels;
 #endif
      row_info->pixel_depth = (png_byte)(row_info->bit_depth *
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -131,7 +131,7 @@ png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
   png_read_data(png_ptr, &(info_ptr->signature[num_checked]), num_to_check);
   png_ptr->sig_bytes = 8;

-   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
   {
      if (num_checked < 4 &&
          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
@@ -217,11 +217,11 @@ png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
      png_crc_read(png_ptr, tmpbuf, len);
   }

-   if (png_crc_error(png_ptr))
+   if (png_crc_error(png_ptr) != 0)
   {
-      if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) ?
-          !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) :
-          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
+      if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0 ?
+          (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0 :
+          (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE) != 0)
      {
         png_chunk_warning(png_ptr, "CRC error");
      }
@@ -245,7 +245,7 @@ png_crc_error(png_structrp png_ptr)
   png_uint_32 crc;
   int need_crc = 1;

-   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
+   if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
   {
      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
@@ -254,7 +254,7 @@ png_crc_error(png_structrp png_ptr)

   else /* critical */
   {
-      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+      if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
         need_crc = 0;
   }

@@ -388,7 +388,7 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
      png_ptr->zstream.next_out = NULL;
      png_ptr->zstream.avail_out = 0;

-      if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
      {
 #if PNG_ZLIB_VERNUM < 0x1240
         ret = inflateReset(&png_ptr->zstream);
@@ -798,7 +798,7 @@ png_handle_IHDR(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_IHDR");

-   if (png_ptr->mode & PNG_HAVE_IHDR)
+   if ((png_ptr->mode & PNG_HAVE_IHDR) != 0)
      png_chunk_error(png_ptr, "out of place");

   /* Check the length */
@@ -874,7 +874,7 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_PLTE");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

   /* Moved to before the 'after IDAT' check below because otherwise duplicate
@@ -882,10 +882,10 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    * than one PLTE, the error is not treated as benign, so this check trumps
    * the requirement that PLTE appears before IDAT.)
    */
-   else if (png_ptr->mode & PNG_HAVE_PLTE)
+   else if ((png_ptr->mode & PNG_HAVE_PLTE) != 0)
      png_chunk_error(png_ptr, "duplicate");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      /* This is benign because the non-benign error happened before, when an
       * IDAT was encountered in a color-mapped image with no PLTE.
@@ -897,7 +897,7 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_ptr->mode |= PNG_HAVE_PLTE;

-   if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "ignored in grayscale PNG");
@@ -964,7 +964,7 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }

 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
-   else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
+   else if (png_crc_error(png_ptr) != 0)  /* Only if we have a CRC error */
   {
      /* If we don't want to use the data from an ancillary chunk,
       * we have two options: an error abort, or a warning and we
@@ -975,9 +975,9 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
       * chunk type to determine whether to check the ancillary or the critical
       * flags.
       */
-      if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE))
+      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_USE) == 0)
      {
-         if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
+         if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) != 0)
            return;

         else
@@ -985,7 +985,7 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      }

      /* Otherwise, we (optionally) emit a warning and use the chunk. */
-      else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
+      else if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN) == 0)
         png_chunk_warning(png_ptr, "CRC error");
   }
 #endif
@@ -1042,7 +1042,8 @@ png_handle_IEND(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
   png_debug(1, "in png_handle_IEND");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR) || !(png_ptr->mode & PNG_HAVE_IDAT))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0 ||
+       (png_ptr->mode & PNG_HAVE_IDAT) == 0)
      png_chunk_error(png_ptr, "out of place");

   png_ptr->mode |= (PNG_AFTER_IDAT | PNG_HAVE_IEND);
@@ -1064,10 +1065,10 @@ png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_gAMA");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
@@ -1083,7 +1084,7 @@ png_handle_gAMA(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buf, 4);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   igamma = png_get_fixed_point(NULL, buf);
@@ -1103,17 +1104,17 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_sBIT");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT))
+   if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -1142,7 +1143,7 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   buf[0] = buf[1] = buf[2] = buf[3] = sample_depth;
   png_crc_read(png_ptr, buf, truelen);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   for (i=0; i<truelen; ++i)
@@ -1152,7 +1153,7 @@ png_handle_sBIT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
         return;
      }

-   if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      png_ptr->sig_bit.red = buf[0];
      png_ptr->sig_bit.green = buf[1];
@@ -1182,10 +1183,10 @@ png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_cHRM");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
@@ -1201,7 +1202,7 @@ png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buf, 32);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   xy.whitex = png_get_fixed_point(NULL, buf);
@@ -1227,10 +1228,10 @@ png_handle_cHRM(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }

   /* If a colorspace error has already been output skip this chunk */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
      return;

-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM)
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0)
   {
      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
      png_colorspace_sync(png_ptr, info_ptr);
@@ -1253,10 +1254,10 @@ png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_sRGB");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
@@ -1272,17 +1273,17 @@ png_handle_sRGB(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, &intent, 1);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   /* If a colorspace error has already been output skip this chunk */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
      return;

   /* Only one sRGB or iCCP chunk is allowed, use the HAVE_INTENT flag to detect
    * this.
    */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT)
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_INTENT) != 0)
   {
      png_ptr->colorspace.flags |= PNG_COLORSPACE_INVALID;
      png_colorspace_sync(png_ptr, info_ptr);
@@ -1305,10 +1306,10 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_iCCP");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE))
+   else if ((png_ptr->mode & (PNG_HAVE_IDAT|PNG_HAVE_PLTE)) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
@@ -1331,7 +1332,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }

   /* If a colorspace error has already been output skip this chunk */
-   if (png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+   if ((png_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
   {
      png_crc_finish(png_ptr, length);
      return;
@@ -1391,14 +1392,14 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                     png_get_uint_32(profile_header);

                  if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
-                     keyword, profile_length))
+                     keyword, profile_length) != 0)
                  {
                     /* The length is apparently ok, so we can check the 132
                      * byte header.
                      */
                     if (png_icc_check_header(png_ptr, &png_ptr->colorspace,
                        keyword, profile_length, profile_header,
-                        png_ptr->color_type))
+                        png_ptr->color_type) != 0)
                     {
                        /* Now read the tag table; a variable size buffer is
                         * needed at this point, allocate one for the whole
@@ -1428,7 +1429,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                           {
                              if (png_icc_check_tag_table(png_ptr,
                                 &png_ptr->colorspace, keyword, profile_length,
-                                 profile))
+                                 profile) != 0)
                              {
                                 /* The profile has been validated for basic
                                  * security issues, so read the whole thing in.
@@ -1602,10 +1603,10 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }
 #endif

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
@@ -1636,7 +1637,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    */
   png_crc_read(png_ptr, buffer, length);

-   if (png_crc_finish(png_ptr, skip))
+   if (png_crc_finish(png_ptr, skip) != 0)
      return;

   buffer[length] = 0;
@@ -1661,7 +1662,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   data_length = length - (png_uint_32)(entry_start - buffer);

   /* Integrity-check the data length */
-   if (data_length % entry_size)
+   if ((data_length % entry_size) != 0)
   {
      png_warning(png_ptr, "sPLT chunk has bad length");
      return;
@@ -1753,17 +1754,17 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_tRNS");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -1806,7 +1807,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
   {
-      if (!(png_ptr->mode & PNG_HAVE_PLTE))
+      if ((png_ptr->mode & PNG_HAVE_PLTE) == 0)
      {
         /* TODO: is this actually an error in the ISO spec? */
         png_crc_finish(png_ptr, length);
@@ -1833,7 +1834,7 @@ png_handle_tRNS(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      return;
   }

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
   {
      png_ptr->num_trans = 0;
      return;
@@ -1858,19 +1859,19 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_bKGD");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if ((png_ptr->mode & PNG_HAVE_IDAT) ||
-      (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
-       !(png_ptr->mode & PNG_HAVE_PLTE)))
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
+       (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
+       (png_ptr->mode & PNG_HAVE_PLTE) == 0))
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -1880,7 +1881,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      truelen = 1;

-   else if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
      truelen = 6;

   else
@@ -1895,7 +1896,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buf, truelen);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   /* We convert the index value into RGB components so that we can allow
@@ -1907,7 +1908,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   {
      background.index = buf[0];

-      if (info_ptr && info_ptr->num_palette)
+      if (info_ptr != NULL && info_ptr->num_palette != 0)
      {
         if (buf[0] >= info_ptr->num_palette)
         {
@@ -1926,7 +1927,7 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      background.gray = 0;
   }

-   else if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* GRAY */
+   else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
   {
      background.index = 0;
      background.red =
@@ -1957,17 +1958,18 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_hIST");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if ((png_ptr->mode & PNG_HAVE_IDAT) || !(png_ptr->mode & PNG_HAVE_PLTE))
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
+       (png_ptr->mode & PNG_HAVE_PLTE) == 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -1991,7 +1993,7 @@ png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      readbuf[i] = png_get_uint_16(buf);
   }

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   png_set_hIST(png_ptr, info_ptr, readbuf);
@@ -2008,17 +2010,17 @@ png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_pHYs");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pHYs) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -2034,7 +2036,7 @@ png_handle_pHYs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buf, 9);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   res_x = png_get_uint_32(buf);
@@ -2054,17 +2056,17 @@ png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_oFFs");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -2080,7 +2082,7 @@ png_handle_oFFs(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buf, 9);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   offset_x = png_get_int_32(buf);
@@ -2103,17 +2105,17 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_pCAL");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -2134,7 +2136,7 @@ png_handle_pCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buffer, length);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   buffer[length] = 0; /* Null terminate the last string */
@@ -2230,17 +2232,17 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_sCAL");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of place");
      return;
   }

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_sCAL) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
@@ -2270,7 +2272,7 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   png_crc_read(png_ptr, buffer, length);
   buffer[length] = 0; /* Null terminate the last string */

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   /* Validate the unit. */
@@ -2286,11 +2288,11 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   i = 1;
   state = 0;

-   if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
+   if (png_check_fp_number((png_const_charp)buffer, length, &state, &i) == 0 ||
       i >= length || buffer[i++] != 0)
      png_chunk_benign_error(png_ptr, "bad width format");

-   else if (!PNG_FP_IS_POSITIVE(state))
+   else if (PNG_FP_IS_POSITIVE(state) == 0)
      png_chunk_benign_error(png_ptr, "non-positive width");

   else
@@ -2298,11 +2300,11 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      png_size_t heighti = i;

      state = 0;
-      if (!png_check_fp_number((png_const_charp)buffer, length, &state, &i) ||
-         i != length)
+      if (png_check_fp_number((png_const_charp)buffer, length,
+          &state, &i) == 0 || i != length)
         png_chunk_benign_error(png_ptr, "bad height format");

-      else if (!PNG_FP_IS_POSITIVE(state))
+      else if (PNG_FP_IS_POSITIVE(state) == 0)
         png_chunk_benign_error(png_ptr, "non-positive height");

      else
@@ -2322,17 +2324,17 @@ png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_debug(1, "in png_handle_tIME");

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME))
+   else if (info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
      return;
   }

-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
      png_ptr->mode |= PNG_AFTER_IDAT;

   if (length != 7)
@@ -2344,7 +2346,7 @@ png_handle_tIME(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buf, 7);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   mod_time.second = buf[6];
@@ -2389,10 +2391,10 @@ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }
 #endif

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
      png_ptr->mode |= PNG_AFTER_IDAT;

 #ifdef PNG_MAX_MALLOC_64K
@@ -2414,7 +2416,7 @@ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buffer, length);

-   if (png_crc_finish(png_ptr, skip))
+   if (png_crc_finish(png_ptr, skip) != 0)
      return;

   key = (png_charp)buffer;
@@ -2434,7 +2436,7 @@ png_handle_tEXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   text_info.text = text;
   text_info.text_length = strlen(text);

-   if (png_set_text_2(png_ptr, info_ptr, &text_info, 1))
+   if (png_set_text_2(png_ptr, info_ptr, &text_info, 1) != 0)
      png_warning(png_ptr, "Insufficient memory to process text chunk");
 }
 #endif
@@ -2468,10 +2470,10 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }
 #endif

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
      png_ptr->mode |= PNG_AFTER_IDAT;

   buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
@@ -2485,7 +2487,7 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buffer, length);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   /* TODO: also check that the keyword contents match the spec! */
@@ -2535,7 +2537,7 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
         text.lang = NULL;
         text.lang_key = NULL;

-         if (png_set_text_2(png_ptr, info_ptr, &text, 1))
+         if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
            errmsg = "insufficient memory";
      }

@@ -2577,10 +2579,10 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   }
 #endif

-   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");

-   if (png_ptr->mode & PNG_HAVE_IDAT)
+   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
      png_ptr->mode |= PNG_AFTER_IDAT;

   buffer = png_read_buffer(png_ptr, length+1, 1/*warn*/);
@@ -2594,7 +2596,7 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)

   png_crc_read(png_ptr, buffer, length);

-   if (png_crc_finish(png_ptr, 0))
+   if (png_crc_finish(png_ptr, 0) != 0)
      return;

   /* First the keyword. */
@@ -2685,7 +2687,7 @@ png_handle_iTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
         text.text_length = 0;
         text.itxt_length = uncompressed_length;

-         if (png_set_text_2(png_ptr, info_ptr, &text, 1))
+         if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
            errmsg = "insufficient memory";
      }
   }
@@ -2713,7 +2715,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)

 #  ifdef PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
      if (png_ptr->user_chunk_malloc_max > 0 &&
-         png_ptr->user_chunk_malloc_max < limit)
+          png_ptr->user_chunk_malloc_max < limit)
         limit = png_ptr->user_chunk_malloc_max;

 #  elif PNG_USER_CHUNK_MALLOC_MAX > 0
@@ -2795,7 +2797,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
       */
      if (png_ptr->read_user_chunk_fn != NULL)
      {
-         if (png_cache_unknown_chunk(png_ptr, length))
+         if (png_cache_unknown_chunk(png_ptr, length) != 0)
         {
            /* Callback to user unknown chunk handler */
            int ret = (*(png_ptr->read_user_chunk_fn))(png_ptr,
@@ -2872,7 +2874,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
            (keep == PNG_HANDLE_CHUNK_IF_SAFE &&
             PNG_CHUNK_ANCILLARY(png_ptr->chunk_name)))
         {
-            if (!png_cache_unknown_chunk(png_ptr, length))
+            if (png_cache_unknown_chunk(png_ptr, length) == 0)
               keep = PNG_HANDLE_CHUNK_NEVER;
         }

@@ -3038,7 +3040,8 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
      end_ptr = dp + PNG_ROWBYTES(pixel_depth, row_width) - 1;
      end_byte = *end_ptr;
 #     ifdef PNG_READ_PACKSWAP_SUPPORTED
-         if (png_ptr->transformations & PNG_PACKSWAP) /* little-endian byte */
+         if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
+            /* little-endian byte */
            end_mask = 0xff << end_mask;

         else /* big-endian byte */
@@ -3054,10 +3057,11 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
    * pass.
    */
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE) &&
-      pass < 6 && (display == 0 ||
-      /* The following copies everything for 'display' on passes 0, 2 and 4. */
-      (display == 1 && (pass & 1) != 0)))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0 &&
+       pass < 6 && (display == 0 ||
+       /* The following copies everything for 'display' on passes 0, 2 and 4. */
+       (display == 1 && (pass & 1) != 0)))
   {
      /* Narrow images may have no bits in a pass; the caller should handle
       * this, but this test is cheap:
@@ -3200,7 +3204,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
         png_uint_32 mask;

 #        ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (png_ptr->transformations & PNG_PACKSWAP)
+            if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
               mask = MASK(pass, pixel_depth, display, 0);

            else
@@ -3351,24 +3355,24 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
                * wide bytes_to_copy either - use the memcpy there.
                */
               if (bytes_to_copy < 16 /*else use memcpy*/ &&
-                  png_isaligned(dp, png_uint_16) &&
-                  png_isaligned(sp, png_uint_16) &&
-                  bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
-                  bytes_to_jump % (sizeof (png_uint_16)) == 0)
+                   png_isaligned(dp, png_uint_16) &&
+                   png_isaligned(sp, png_uint_16) &&
+                   bytes_to_copy % (sizeof (png_uint_16)) == 0 &&
+                   bytes_to_jump % (sizeof (png_uint_16)) == 0)
               {
                  /* Everything is aligned for png_uint_16 copies, but try for
                   * png_uint_32 first.
                   */
-                  if (png_isaligned(dp, png_uint_32) &&
-                     png_isaligned(sp, png_uint_32) &&
-                     bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
-                     bytes_to_jump % (sizeof (png_uint_32)) == 0)
+                  if (png_isaligned(dp, png_uint_32) != 0 &&
+                      png_isaligned(sp, png_uint_32) != 0 &&
+                      bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
+                      bytes_to_jump % (sizeof (png_uint_32)) == 0)
                  {
                     png_uint_32p dp32 = png_aligncast(png_uint_32p,dp);
                     png_const_uint_32p sp32 = png_aligncastconst(
-                        png_const_uint_32p, sp);
+                         png_const_uint_32p, sp);
                     size_t skip = (bytes_to_jump-bytes_to_copy) /
-                        (sizeof (png_uint_32));
+                         (sizeof (png_uint_32));

                     do
                     {
@@ -3507,7 +3511,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
            int j;

 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (transformations & PNG_PACKSWAP)
+            if ((transformations & PNG_PACKSWAP) != 0)
            {
                sshift = (int)((row_info->width + 7) & 0x07);
                dshift = (int)((final_width + 7) & 0x07);
@@ -3567,7 +3571,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
            png_uint_32 i;

 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (transformations & PNG_PACKSWAP)
+            if ((transformations & PNG_PACKSWAP) != 0)
            {
               sshift = (int)(((row_info->width + 3) & 0x03) << 1);
               dshift = (int)(((final_width + 3) & 0x03) << 1);
@@ -3630,7 +3634,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
            int jstop = png_pass_inc[pass];

 #ifdef PNG_READ_PACKSWAP_SUPPORTED
-            if (transformations & PNG_PACKSWAP)
+            if ((transformations & PNG_PACKSWAP) != 0)
            {
               sshift = (int)(((row_info->width + 1) & 0x01) << 2);
               dshift = (int)(((final_width + 1) & 0x01) << 2);
@@ -4071,7 +4075,7 @@ png_read_finish_IDAT(png_structrp png_ptr)
    * read it otherwise stray unread IDAT data or, more likely, an IDAT chunk
    * may still remain to be consumed.
    */
-   if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+   if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
   {
      /* The NULL causes png_read_IDAT_data to swallow any remaining bytes in
       * the compressed stream, but the stream may be damaged too, so even after
@@ -4083,7 +4087,7 @@ png_read_finish_IDAT(png_structrp png_ptr)
      /* Now clear everything out for safety; the following may not have been
       * done.
       */
-      if (!(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED) == 0)
      {
         png_ptr->mode |= PNG_AFTER_IDAT;
         png_ptr->flags |= PNG_FLAG_ZSTREAM_ENDED;
@@ -4133,7 +4137,7 @@ png_read_finish_row(png_structrp png_ptr)
   if (png_ptr->row_number < png_ptr->num_rows)
      return;

-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
   {
      png_ptr->row_number = 0;

@@ -4154,7 +4158,7 @@ png_read_finish_row(png_structrp png_ptr)
            png_pass_start[png_ptr->pass]) /
            png_pass_inc[png_ptr->pass];

-         if (!(png_ptr->transformations & PNG_INTERLACE))
+         if ((png_ptr->transformations & PNG_INTERLACE) == 0)
         {
            png_ptr->num_rows = (png_ptr->height +
                png_pass_yinc[png_ptr->pass] - 1 -
@@ -4201,9 +4205,9 @@ png_read_start_row(png_structrp png_ptr)
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
   png_init_read_transformations(png_ptr);
 #endif
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
   {
-      if (!(png_ptr->transformations & PNG_INTERLACE))
+      if ((png_ptr->transformations & PNG_INTERLACE) == 0)
         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
             png_pass_ystart[0]) / png_pass_yinc[0];

@@ -4235,16 +4239,16 @@ png_read_start_row(png_structrp png_ptr)
    * TODO: fix this.
    */
 #ifdef PNG_READ_PACK_SUPPORTED
-   if ((png_ptr->transformations & PNG_PACK) && png_ptr->bit_depth < 8)
+   if ((png_ptr->transformations & PNG_PACK) != 0 && png_ptr->bit_depth < 8)
      max_pixel_depth = 8;
 #endif

 #ifdef PNG_READ_EXPAND_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND)
+   if ((png_ptr->transformations & PNG_EXPAND) != 0)
   {
      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
            max_pixel_depth = 32;

         else
@@ -4256,13 +4260,13 @@ png_read_start_row(png_structrp png_ptr)
         if (max_pixel_depth < 8)
            max_pixel_depth = 8;

-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
            max_pixel_depth *= 2;
      }

      else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
      {
-         if (png_ptr->num_trans)
+         if (png_ptr->num_trans != 0)
         {
            max_pixel_depth *= 4;
            max_pixel_depth /= 3;
@@ -4272,13 +4276,13 @@ png_read_start_row(png_structrp png_ptr)
 #endif

 #ifdef PNG_READ_EXPAND_16_SUPPORTED
-   if (png_ptr->transformations & PNG_EXPAND_16)
+   if ((png_ptr->transformations & PNG_EXPAND_16) != 0)
   {
 #     ifdef PNG_READ_EXPAND_SUPPORTED
         /* In fact it is an error if it isn't supported, but checking is
          * the safe way.
          */
-         if (png_ptr->transformations & PNG_EXPAND)
+         if ((png_ptr->transformations & PNG_EXPAND) != 0)
         {
            if (png_ptr->bit_depth < 16)
               max_pixel_depth *= 2;
@@ -4290,7 +4294,7 @@ png_read_start_row(png_structrp png_ptr)
 #endif

 #ifdef PNG_READ_FILLER_SUPPORTED
-   if (png_ptr->transformations & (PNG_FILLER))
+   if ((png_ptr->transformations & (PNG_FILLER)) != 0)
   {
      if (png_ptr->color_type == PNG_COLOR_TYPE_GRAY)
      {
@@ -4314,14 +4318,15 @@ png_read_start_row(png_structrp png_ptr)
 #endif

 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-   if (png_ptr->transformations & PNG_GRAY_TO_RGB)
+   if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
   {
      if (
 #ifdef PNG_READ_EXPAND_SUPPORTED
-          (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND)) ||
+          (png_ptr->num_trans != 0 &&
+          (png_ptr->transformations & PNG_EXPAND) != 0) ||
 #endif
 #ifdef PNG_READ_FILLER_SUPPORTED
-          (png_ptr->transformations & (PNG_FILLER)) ||
+          (png_ptr->transformations & (PNG_FILLER)) != 0 ||
 #endif
          png_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
      {
@@ -4354,7 +4359,7 @@ png_read_start_row(png_structrp png_ptr)

 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) && \
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
   {
      int user_pixel_depth = png_ptr->user_transform_depth *
         png_ptr->user_transform_channels;
@@ -4390,7 +4395,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
     png_free(png_ptr, png_ptr->big_row_buf);
     png_free(png_ptr, png_ptr->big_prev_row);

-     if (png_ptr->interlaced)
+     if (png_ptr->interlaced != 0)
        png_ptr->big_row_buf = (png_bytep)png_calloc(png_ptr,
            row_bytes + 48);

@@ -4447,7 +4452,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    * does not, so free the read buffer now regardless; the sequential reader
    * reallocates it on demand.
    */
-   if (png_ptr->read_buffer)
+   if (png_ptr->read_buffer != 0)
   {
      png_bytep buffer = png_ptr->read_buffer;

--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@

 /* pngset.c - storage of image information into info struct
 *
- * Last changed in libpng 1.6.11 [June 5, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -59,7 +59,7 @@ png_set_cHRM_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
   xy.whitey = white_y;

   if (png_colorspace_set_chromaticities(png_ptr, &info_ptr->colorspace, &xy,
-      2/* override with app values*/))
+       2/* override with app values*/) != 0)
      info_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;

   png_colorspace_sync_info(png_ptr, info_ptr);
@@ -90,7 +90,8 @@ png_set_cHRM_XYZ_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
   XYZ.blue_Y = int_blue_Y;
   XYZ.blue_Z = int_blue_Z;

-   if (png_colorspace_set_endpoints(png_ptr, &info_ptr->colorspace, &XYZ, 2))
+   if (png_colorspace_set_endpoints(png_ptr, &info_ptr->colorspace,
+       &XYZ, 2) != 0)
      info_ptr->colorspace.flags |= PNG_COLORSPACE_FROM_cHRM;

   png_colorspace_sync_info(png_ptr, info_ptr);
@@ -227,13 +228,13 @@ png_set_IHDR(png_const_structrp png_ptr, png_inforp info_ptr,
   if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      info_ptr->channels = 1;

-   else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
+   else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
      info_ptr->channels = 3;

   else
      info_ptr->channels = 1;

-   if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
+   if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      info_ptr->channels++;

   info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);
@@ -288,12 +289,14 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,

   /* Validate params[nparams] */
   for (i=0; i<nparams; ++i)
+   {
      if (params[i] == NULL ||
-         !png_check_fp_string(params[i], strlen(params[i])))
+          !png_check_fp_string(params[i], strlen(params[i])))
         png_error(png_ptr, "Invalid format for pCAL parameter");
+   }

   info_ptr->pcal_purpose = png_voidcast(png_charp,
-      png_malloc_warn(png_ptr, length));
+       png_malloc_warn(png_ptr, length));

   if (info_ptr->pcal_purpose == NULL)
   {
@@ -594,7 +597,8 @@ png_set_sRGB_gAMA_and_cHRM(png_const_structrp png_ptr, png_inforp info_ptr,
   if (png_ptr == NULL || info_ptr == NULL)
      return;

-   if (png_colorspace_set_sRGB(png_ptr, &info_ptr->colorspace, srgb_intent))
+   if (png_colorspace_set_sRGB(png_ptr, &info_ptr->colorspace,
+       srgb_intent) != 0)
   {
      /* This causes the gAMA and cHRM to be written too */
      info_ptr->colorspace.flags |=
@@ -891,7 +895,7 @@ png_set_tIME(png_const_structrp png_ptr, png_inforp info_ptr,
   png_debug1(1, "in %s storage function", "tIME");

   if (png_ptr == NULL || info_ptr == NULL || mod_time == NULL ||
-       (png_ptr->mode & PNG_WROTE_tIME))
+       (png_ptr->mode & PNG_WROTE_tIME) != 0)
      return;

   if (mod_time->month == 0   || mod_time->month > 12  ||
@@ -1077,7 +1081,7 @@ check_location(png_const_structrp png_ptr, int location)
    * change; previously the app had to use the
    * png_set_unknown_chunk_location API below for each chunk.
    */
-   if (location == 0 && !(png_ptr->mode & PNG_IS_READ_STRUCT))
+   if (location == 0 && (png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
   {
      /* Write struct, so unknown chunks come from the app */
      png_app_warning(png_ptr,
@@ -1123,7 +1127,7 @@ png_set_unknown_chunks(png_const_structrp png_ptr,
    */
 #  if !defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) && \
      defined(PNG_READ_SUPPORTED)
-      if (png_ptr->mode & PNG_IS_READ_STRUCT)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
      {
         png_app_error(png_ptr, "no unknown chunk support on read");
         return;
@@ -1131,7 +1135,7 @@ png_set_unknown_chunks(png_const_structrp png_ptr,
 #  endif
 #  if !defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED) && \
      defined(PNG_WRITE_SUPPORTED)
-      if (!(png_ptr->mode & PNG_IS_READ_STRUCT))
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
      {
         png_app_error(png_ptr, "no unknown chunk support on write");
         return;
@@ -1217,7 +1221,7 @@ png_set_unknown_chunk_location(png_const_structrp png_ptr, png_inforp info_ptr,
      {
         png_app_error(png_ptr, "invalid unknown chunk location");
         /* Fake out the pre 1.6.0 behavior: */
-         if ((location & PNG_HAVE_IDAT)) /* undocumented! */
+         if ((location & PNG_HAVE_IDAT) != 0) /* undocumented! */
            location = PNG_AFTER_IDAT;

         else
@@ -1255,10 +1259,13 @@ add_one_chunk(png_bytep list, unsigned int count, png_const_bytep add, int keep)
   /* Utility function: update the 'keep' state of a chunk if it is already in
    * the list, otherwise add it to the list.
    */
-   for (i=0; i<count; ++i, list += 5) if (memcmp(list, add, 4) == 0)
+   for (i=0; i<count; ++i, list += 5)
   {
-      list[4] = (png_byte)keep;
-      return count;
+      if (memcmp(list, add, 4) == 0)
+      {
+         list[4] = (png_byte)keep;
+         return count;
+      }
   }

   if (keep != PNG_HANDLE_CHUNK_AS_DEFAULT)
@@ -1382,12 +1389,15 @@ png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
      unsigned int i;

      for (i=0; i<num_chunks; ++i)
+      {
         old_num_chunks = add_one_chunk(new_list, old_num_chunks,
            chunk_list+5*i, keep);
+      }

      /* Now remove any spurious 'default' entries. */
      num_chunks = 0;
      for (i=0, inlist=outlist=new_list; i<old_num_chunks; ++i, inlist += 5)
+      {
         if (inlist[4])
         {
            if (outlist != inlist)
@@ -1395,6 +1405,7 @@ png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
            outlist += 5;
            ++num_chunks;
         }
+      }

      /* This means the application has removed all the specialized handling. */
      if (num_chunks == 0)
@@ -1446,7 +1457,8 @@ png_set_rows(png_const_structrp png_ptr, png_inforp info_ptr,
   if (png_ptr == NULL || info_ptr == NULL)
      return;

-   if (info_ptr->row_pointers && (info_ptr->row_pointers != row_pointers))
+   if (info_ptr->row_pointers != NULL &&
+       (info_ptr->row_pointers != row_pointers))
      png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);

   info_ptr->row_pointers = row_pointers;
@@ -1466,7 +1478,7 @@ png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
       png_error(png_ptr, "invalid compression buffer size");

 #  ifdef PNG_SEQUENTIAL_READ_SUPPORTED
-      if (png_ptr->mode & PNG_IS_READ_STRUCT)
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
      {
         png_ptr->IDAT_read_size = (png_uint_32)size; /* checked above */
         return;
@@ -1474,7 +1486,7 @@ png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
 #  endif

 #  ifdef PNG_WRITE_SUPPORTED
-      if (!(png_ptr->mode & PNG_IS_READ_STRUCT))
+      if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
      {
         if (png_ptr->zowner != 0)
         {
@@ -1512,7 +1524,7 @@ png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
 void PNGAPI
 png_set_invalid(png_const_structrp png_ptr, png_inforp info_ptr, int mask)
 {
-   if (png_ptr && info_ptr)
+   if (png_ptr != NULL && info_ptr != NULL)
      info_ptr->valid &= ~mask;
 }

--- a/pngtest.c
+++ b/pngtest.c
@@ -283,7 +283,8 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
       png_uint_32 n, nstop;
       int channel;
       int color_channels = row_info->channels;
-       if (row_info->color_type > 3)color_channels--;
+       if (row_info->color_type > 3)
+          color_channels--;

       for (n = 0, nstop=row_info->width; n<nstop; n++)
       {
@@ -643,7 +644,7 @@ set_location(png_structp png_ptr, struct user_chunk_data *data, int what)
 {
   int location;

-   if ((data->location[0] & what) || (data->location[1] & what))
+   if ((data->location[0] & what) != 0 || (data->location[1] & what) != 0)
      return 0; /* already have one of these */

   /* Find where we are (the code below zeroes info_ptr to indicate that the
@@ -652,7 +653,7 @@ set_location(png_structp png_ptr, struct user_chunk_data *data, int what)
   if (data->info_ptr == NULL) /* after IDAT */
      location = what | after_IDAT;

-   else if (png_get_valid(png_ptr, data->info_ptr, PNG_INFO_PLTE))
+   else if (png_get_valid(png_ptr, data->info_ptr, PNG_INFO_PLTE) != 0)
      location = what | before_IDAT;

   else
@@ -699,7 +700,7 @@ read_user_chunk_callback(png_struct *png_ptr, png_unknown_chunkp chunk)
         if (chunk->data[0] != 0 && chunk->data[0] != 1)
            return (-1);  /* Invalid mode */

-         if (set_location(png_ptr, my_user_chunk_data, have_sTER))
+         if (set_location(png_ptr, my_user_chunk_data, have_sTER) != 0)
         {
            my_user_chunk_data->sTER_mode=chunk->data[0];
            return (1);
@@ -718,7 +719,7 @@ read_user_chunk_callback(png_struct *png_ptr, png_unknown_chunkp chunk)
   if (chunk->size != 9)
      return (-1); /* Error return */

-   if (!set_location(png_ptr, my_user_chunk_data, have_vpAg))
+   if (set_location(png_ptr, my_user_chunk_data, have_vpAg) == 0)
      return (0);  /* duplicate vpAg */

   my_user_chunk_data->vpAg_width = png_get_uint_31(png_ptr, chunk->data);
@@ -1049,7 +1050,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      int interlace_type, compression_type, filter_type;

      if (png_get_IHDR(read_ptr, read_info_ptr, &width, &height, &bit_depth,
-          &color_type, &interlace_type, &compression_type, &filter_type))
+          &color_type, &interlace_type, &compression_type, &filter_type) != 0)
      {
         png_set_IHDR(write_ptr, write_info_ptr, width, height, bit_depth,
            color_type, interlace_type, compression_type, filter_type);
@@ -1082,7 +1083,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         blue_y;

      if (png_get_cHRM_fixed(read_ptr, read_info_ptr, &white_x, &white_y,
-         &red_x, &red_y, &green_x, &green_y, &blue_x, &blue_y))
+         &red_x, &red_y, &green_x, &green_y, &blue_x, &blue_y) != 0)
      {
         png_set_cHRM_fixed(write_ptr, write_info_ptr, white_x, white_y, red_x,
            red_y, green_x, green_y, blue_x, blue_y);
@@ -1093,7 +1094,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_fixed_point gamma;

-      if (png_get_gAMA_fixed(read_ptr, read_info_ptr, &gamma))
+      if (png_get_gAMA_fixed(read_ptr, read_info_ptr, &gamma) != 0)
         png_set_gAMA_fixed(write_ptr, write_info_ptr, gamma);
   }
 #endif
@@ -1105,7 +1106,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         blue_y;

      if (png_get_cHRM(read_ptr, read_info_ptr, &white_x, &white_y, &red_x,
-         &red_y, &green_x, &green_y, &blue_x, &blue_y))
+         &red_y, &green_x, &green_y, &blue_x, &blue_y) != 0)
      {
         png_set_cHRM(write_ptr, write_info_ptr, white_x, white_y, red_x,
            red_y, green_x, green_y, blue_x, blue_y);
@@ -1116,7 +1117,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      double gamma;

-      if (png_get_gAMA(read_ptr, read_info_ptr, &gamma))
+      if (png_get_gAMA(read_ptr, read_info_ptr, &gamma) != 0)
         png_set_gAMA(write_ptr, write_info_ptr, gamma);
   }
 #endif
@@ -1130,7 +1131,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      int compression_type;

      if (png_get_iCCP(read_ptr, read_info_ptr, &name, &compression_type,
-                      &profile, &proflen))
+                      &profile, &proflen) != 0)
      {
         png_set_iCCP(write_ptr, write_info_ptr, name, compression_type,
                      profile, proflen);
@@ -1141,7 +1142,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      int intent;

-      if (png_get_sRGB(read_ptr, read_info_ptr, &intent))
+      if (png_get_sRGB(read_ptr, read_info_ptr, &intent) != 0)
         png_set_sRGB(write_ptr, write_info_ptr, intent);
   }
 #endif
@@ -1149,14 +1150,14 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      png_colorp palette;
      int num_palette;

-      if (png_get_PLTE(read_ptr, read_info_ptr, &palette, &num_palette))
+      if (png_get_PLTE(read_ptr, read_info_ptr, &palette, &num_palette) != 0)
         png_set_PLTE(write_ptr, write_info_ptr, palette, num_palette);
   }
 #ifdef PNG_bKGD_SUPPORTED
   {
      png_color_16p background;

-      if (png_get_bKGD(read_ptr, read_info_ptr, &background))
+      if (png_get_bKGD(read_ptr, read_info_ptr, &background) != 0)
      {
         png_set_bKGD(write_ptr, write_info_ptr, background);
      }
@@ -1166,7 +1167,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_uint_16p hist;

-      if (png_get_hIST(read_ptr, read_info_ptr, &hist))
+      if (png_get_hIST(read_ptr, read_info_ptr, &hist) != 0)
         png_set_hIST(write_ptr, write_info_ptr, hist);
   }
 #endif
@@ -1176,7 +1177,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      int unit_type;

      if (png_get_oFFs(read_ptr, read_info_ptr, &offset_x, &offset_y,
-          &unit_type))
+          &unit_type) != 0)
      {
         png_set_oFFs(write_ptr, write_info_ptr, offset_x, offset_y, unit_type);
      }
@@ -1190,7 +1191,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      int type, nparams;

      if (png_get_pCAL(read_ptr, read_info_ptr, &purpose, &X0, &X1, &type,
-         &nparams, &units, &params))
+         &nparams, &units, &params) != 0)
      {
         png_set_pCAL(write_ptr, write_info_ptr, purpose, X0, X1, type,
            nparams, units, params);
@@ -1202,7 +1203,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      png_uint_32 res_x, res_y;
      int unit_type;

-      if (png_get_pHYs(read_ptr, read_info_ptr, &res_x, &res_y, &unit_type))
+      if (png_get_pHYs(read_ptr, read_info_ptr, &res_x, &res_y,
+          &unit_type) != 0)
         png_set_pHYs(write_ptr, write_info_ptr, res_x, res_y, unit_type);
   }
 #endif
@@ -1210,7 +1212,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_color_8p sig_bit;

-      if (png_get_sBIT(read_ptr, read_info_ptr, &sig_bit))
+      if (png_get_sBIT(read_ptr, read_info_ptr, &sig_bit) != 0)
         png_set_sBIT(write_ptr, write_info_ptr, sig_bit);
   }
 #endif
@@ -1222,7 +1224,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      double scal_width, scal_height;

      if (png_get_sCAL(read_ptr, read_info_ptr, &unit, &scal_width,
-         &scal_height))
+         &scal_height) != 0)
      {
         png_set_sCAL(write_ptr, write_info_ptr, unit, scal_width, scal_height);
      }
@@ -1234,7 +1236,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      png_charp scal_width, scal_height;

      if (png_get_sCAL_s(read_ptr, read_info_ptr, &unit, &scal_width,
-          &scal_height))
+          &scal_height) != 0)
      {
         png_set_sCAL_s(write_ptr, write_info_ptr, unit, scal_width,
             scal_height);
@@ -1274,11 +1276,11 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_timep mod_time;

-      if (png_get_tIME(read_ptr, read_info_ptr, &mod_time))
+      if (png_get_tIME(read_ptr, read_info_ptr, &mod_time) != 0)
      {
         png_set_tIME(write_ptr, write_info_ptr, mod_time);
 #ifdef PNG_TIME_RFC1123_SUPPORTED
-         if (png_convert_to_rfc1123_buffer(tIME_string, mod_time))
+         if (png_convert_to_rfc1123_buffer(tIME_string, mod_time) != 0)
            tIME_string[(sizeof tIME_string) - 1] = '\0';

         else
@@ -1299,7 +1301,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      png_color_16p trans_color;

      if (png_get_tRNS(read_ptr, read_info_ptr, &trans_alpha, &num_trans,
-         &trans_color))
+         &trans_color) != 0)
      {
         int sample_max = (1 << bit_depth);
         /* libpng doesn't reject a tRNS chunk with out-of-range samples */
@@ -1457,11 +1459,11 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   {
      png_timep mod_time;

-      if (png_get_tIME(read_ptr, end_info_ptr, &mod_time))
+      if (png_get_tIME(read_ptr, end_info_ptr, &mod_time) != 0)
      {
         png_set_tIME(write_ptr, write_end_info_ptr, mod_time);
 #ifdef PNG_TIME_RFC1123_SUPPORTED
-         if (png_convert_to_rfc1123_buffer(tIME_string, mod_time))
+         if (png_convert_to_rfc1123_buffer(tIME_string, mod_time) != 0)
            tIME_string[(sizeof tIME_string) - 1] = '\0';

         else
@@ -1824,7 +1826,7 @@ main(int argc, char *argv[])
 #endif
 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
            for (k = 0; k<256; k++)
-               if (filters_used[k])
+               if (filters_used[k] != 0)
                  fprintf(STDERR, " Filter %d was used %lu times\n",
                     k, (unsigned long)filters_used[k]);
 #endif
@@ -1915,7 +1917,7 @@ main(int argc, char *argv[])
 #endif
 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
                for (k = 0; k<256; k++)
-                   if (filters_used[k])
+                   if (filters_used[k] != 0)
                      fprintf(STDERR, " Filter %d was used %lu times\n",
                         k, (unsigned long)filters_used[k]);
 #endif
@@ -2006,4 +2008,4 @@ main(void)
 #endif

 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_15beta01 Your_png_h_is_not_version_1_6_15beta01;
+typedef png_libpng_version_1_6_15beta04 Your_png_h_is_not_version_1_6_15beta04;
--- 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 1.6.11 [June 5, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -100,7 +100,7 @@ png_set_interlace_handling(png_structrp png_ptr)
 {
   png_debug(1, "in png_set_interlace handling");

-   if (png_ptr && png_ptr->interlaced)
+   if (png_ptr != 0 && png_ptr->interlaced != 0)
   {
      png_ptr->transformations |= PNG_INTERLACE;
      return (7);
@@ -127,7 +127,7 @@ png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
   /* In libpng 1.6 it is possible to determine whether this is a read or write
    * operation and therefore to do more checking here for a valid call.
    */
-   if (png_ptr->mode & PNG_IS_READ_STRUCT)
+   if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
   {
 #     ifdef PNG_READ_FILLER_SUPPORTED
         /* On read png_set_filler is always valid, regardless of the base PNG
@@ -210,7 +210,7 @@ png_set_add_alpha(png_structrp png_ptr, png_uint_32 filler, int filler_loc)

   png_set_filler(png_ptr, filler, filler_loc);
   /* The above may fail to do anything. */
-   if (png_ptr->transformations & PNG_FILLER)
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
      png_ptr->transformations |= PNG_ADD_ALPHA;
 }

@@ -605,7 +605,7 @@ png_do_bgr(png_row_infop row_info, png_bytep row)
 {
   png_debug(1, "in png_do_bgr");

-   if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      png_uint_32 row_width = row_info->width;
      if (row_info->bit_depth == 8)
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -24,7 +24,7 @@ static void
 write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
   unsigned int where)
 {
-   if (info_ptr->unknown_chunks_num)
+   if (info_ptr->unknown_chunks_num != 0)
   {
      png_const_unknown_chunkp up;

@@ -33,7 +33,7 @@ write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
      for (up = info_ptr->unknown_chunks;
           up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
           ++up)
-         if (up->location & where)
+         if ((up->location & where) != 0)
      {
         /* If per-chunk unknown chunk handling is enabled use it, otherwise
          * just write the chunks the application has set.
@@ -88,14 +88,14 @@ png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
   if (png_ptr == NULL || info_ptr == NULL)
      return;

-   if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
+   if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
   {
   /* Write PNG signature */
   png_write_sig(png_ptr);

 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   if ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) && \
-       (png_ptr->mng_features_permitted))
+   if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 && \
+       png_ptr->mng_features_permitted != 0)
   {
      png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
      png_ptr->mng_features_permitted = 0;
@@ -129,9 +129,9 @@ png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
    */
 #ifdef PNG_GAMMA_SUPPORTED
 #  ifdef PNG_WRITE_gAMA_SUPPORTED
-      if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
-         (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) &&
-         (info_ptr->valid & PNG_INFO_gAMA))
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+          (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) != 0 &&
+          (info_ptr->valid & PNG_INFO_gAMA) != 0)
         png_write_gAMA_fixed(png_ptr, info_ptr->colorspace.gamma);
 #  endif
 #endif
@@ -141,11 +141,11 @@ png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
    * and it matches one of the known sRGB ones issue a warning.
    */
 #  ifdef PNG_WRITE_iCCP_SUPPORTED
-      if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
-         (info_ptr->valid & PNG_INFO_iCCP))
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+          (info_ptr->valid & PNG_INFO_iCCP) != 0)
      {
 #        ifdef PNG_WRITE_sRGB_SUPPORTED
-            if (info_ptr->valid & PNG_INFO_sRGB)
+            if ((info_ptr->valid & PNG_INFO_sRGB) != 0)
               png_app_warning(png_ptr,
                  "profile matches sRGB but writing iCCP instead");
 #        endif
@@ -159,22 +159,22 @@ png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
 #  endif

 #  ifdef PNG_WRITE_sRGB_SUPPORTED
-      if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
-         (info_ptr->valid & PNG_INFO_sRGB))
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+          (info_ptr->valid & PNG_INFO_sRGB) != 0)
         png_write_sRGB(png_ptr, info_ptr->colorspace.rendering_intent);
 #  endif /* WRITE_sRGB */
 #endif /* COLORSPACE */

 #ifdef PNG_WRITE_sBIT_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sBIT)
+   if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
      png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
 #endif

 #ifdef PNG_COLORSPACE_SUPPORTED
 #  ifdef PNG_WRITE_cHRM_SUPPORTED
-      if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
-         (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) &&
-         (info_ptr->valid & PNG_INFO_cHRM))
+      if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
+         (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0 &&
+         (info_ptr->valid & PNG_INFO_cHRM) != 0)
         png_write_cHRM_fixed(png_ptr, &info_ptr->colorspace.end_points_xy);
 #  endif
 #endif
@@ -201,19 +201,19 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)

   png_write_info_before_PLTE(png_ptr, info_ptr);

-   if (info_ptr->valid & PNG_INFO_PLTE)
+   if ((info_ptr->valid & PNG_INFO_PLTE) != 0)
      png_write_PLTE(png_ptr, info_ptr->palette,
          (png_uint_32)info_ptr->num_palette);

-   else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+   else if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) !=0)
      png_error(png_ptr, "Valid palette required for paletted images");

 #ifdef PNG_WRITE_tRNS_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_tRNS)
+   if ((info_ptr->valid & PNG_INFO_tRNS) !=0)
   {
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
      /* Invert the alpha channel (in tRNS) */
-      if ((png_ptr->transformations & PNG_INVERT_ALPHA) &&
+      if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0 &&
          info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
         int j;
@@ -227,42 +227,42 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
   }
 #endif
 #ifdef PNG_WRITE_bKGD_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_bKGD)
+   if ((info_ptr->valid & PNG_INFO_bKGD) != 0)
      png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
 #endif

 #ifdef PNG_WRITE_hIST_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_hIST)
+   if ((info_ptr->valid & PNG_INFO_hIST) != 0)
      png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
 #endif

 #ifdef PNG_WRITE_oFFs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_oFFs)
+   if ((info_ptr->valid & PNG_INFO_oFFs) != 0)
      png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
          info_ptr->offset_unit_type);
 #endif

 #ifdef PNG_WRITE_pCAL_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pCAL)
+   if ((info_ptr->valid & PNG_INFO_pCAL) != 0)
      png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
          info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
          info_ptr->pcal_units, info_ptr->pcal_params);
 #endif

 #ifdef PNG_WRITE_sCAL_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sCAL)
+   if ((info_ptr->valid & PNG_INFO_sCAL) != 0)
      png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
          info_ptr->scal_s_width, info_ptr->scal_s_height);
 #endif /* sCAL */

 #ifdef PNG_WRITE_pHYs_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_pHYs)
+   if ((info_ptr->valid & PNG_INFO_pHYs) != 0)
      png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
          info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
 #endif /* pHYs */

 #ifdef PNG_WRITE_tIME_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_tIME)
+   if ((info_ptr->valid & PNG_INFO_tIME) != 0)
   {
      png_write_tIME(png_ptr, &(info_ptr->mod_time));
      png_ptr->mode |= PNG_WROTE_tIME;
@@ -270,7 +270,7 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
 #endif /* tIME */

 #ifdef PNG_WRITE_sPLT_SUPPORTED
-   if (info_ptr->valid & PNG_INFO_sPLT)
+   if ((info_ptr->valid & PNG_INFO_sPLT) != 0)
      for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
         png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
 #endif /* sPLT */
@@ -351,7 +351,7 @@ png_write_end(png_structrp png_ptr, png_inforp info_ptr)
   if (png_ptr == NULL)
      return;

-   if (!(png_ptr->mode & PNG_HAVE_IDAT))
+   if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
      png_error(png_ptr, "No IDATs written into file");

 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
@@ -367,8 +367,8 @@ png_write_end(png_structrp png_ptr, png_inforp info_ptr)
 #endif
 #ifdef PNG_WRITE_tIME_SUPPORTED
      /* Check to see if user has supplied a time chunk */
-      if ((info_ptr->valid & PNG_INFO_tIME) &&
-          !(png_ptr->mode & PNG_WROTE_tIME))
+      if ((info_ptr->valid & PNG_INFO_tIME) != 0 &&
+          (png_ptr->mode & PNG_WROTE_tIME) == 0)
         png_write_tIME(png_ptr, &(info_ptr->mod_time));

 #endif
@@ -618,7 +618,7 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 {
   png_debug(1, "in png_do_write_intrapixel");

-   if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      int bytes_per_pixel;
      png_uint_32 row_width = row_info->width;
@@ -693,44 +693,44 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
   if (png_ptr->row_number == 0 && png_ptr->pass == 0)
   {
      /* Make sure we wrote the header info */
-      if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
+      if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
         png_error(png_ptr,
             "png_write_info was never called before png_write_row");

      /* Check for transforms that have been set but were defined out */
 #if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
-      if (png_ptr->transformations & PNG_INVERT_MONO)
+      if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
         png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
 #endif

 #if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
-      if (png_ptr->transformations & PNG_FILLER)
+      if ((png_ptr->transformations & PNG_FILLER) != 0)
         png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
 #endif
 #if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
    defined(PNG_READ_PACKSWAP_SUPPORTED)
-      if (png_ptr->transformations & PNG_PACKSWAP)
+      if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
         png_warning(png_ptr,
             "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
 #endif

 #if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
-      if (png_ptr->transformations & PNG_PACK)
+      if ((png_ptr->transformations & PNG_PACK) != 0)
         png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
 #endif

 #if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
-      if (png_ptr->transformations & PNG_SHIFT)
+      if ((png_ptr->transformations & PNG_SHIFT) != 0)
         png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
 #endif

 #if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
-      if (png_ptr->transformations & PNG_BGR)
+      if ((png_ptr->transformations & PNG_BGR) != 0)
         png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
 #endif

 #if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
-      if (png_ptr->transformations & PNG_SWAP_BYTES)
+      if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
         png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
 #endif

@@ -739,12 +739,13 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)

 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
   /* If interlaced and not interested in row, return */
-   if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
+   if (png_ptr->interlaced != 0 &&
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
   {
      switch (png_ptr->pass)
      {
         case 0:
-            if (png_ptr->row_number & 0x07)
+            if ((png_ptr->row_number & 0x07) != 0)
            {
               png_write_finish_row(png_ptr);
               return;
@@ -752,7 +753,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
            break;

         case 1:
-            if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
+            if ((png_ptr->row_number & 0x07) != 0 || png_ptr->width < 5)
            {
               png_write_finish_row(png_ptr);
               return;
@@ -768,7 +769,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
            break;

         case 3:
-            if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
+            if ((png_ptr->row_number & 0x03) != 0 || png_ptr->width < 3)
            {
               png_write_finish_row(png_ptr);
               return;
@@ -784,7 +785,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
            break;

         case 5:
-            if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
+            if ((png_ptr->row_number & 0x01) != 0 || png_ptr->width < 2)
            {
               png_write_finish_row(png_ptr);
               return;
@@ -792,7 +793,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
            break;

         case 6:
-            if (!(png_ptr->row_number & 0x01))
+            if ((png_ptr->row_number & 0x01) == 0)
            {
               png_write_finish_row(png_ptr);
               return;
@@ -826,7 +827,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
   /* Handle interlacing */
   if (png_ptr->interlaced && png_ptr->pass < 6 &&
-       (png_ptr->transformations & PNG_INTERLACE))
+       (png_ptr->transformations & PNG_INTERLACE) != 0)
   {
      png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
      /* This should always get caught above, but still ... */
@@ -840,7 +841,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)

 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
   /* Handle other transformations */
-   if (png_ptr->transformations)
+   if (png_ptr->transformations != 0)
      png_do_write_transformations(png_ptr, &row_info);
 #endif

@@ -861,7 +862,7 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
    * 4. The filter_method is 64 and
    * 5. The color_type is RGB or RGBA
    */
-   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
       (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
   {
      /* Intrapixel differencing */
@@ -927,7 +928,7 @@ png_write_destroy(png_structrp png_ptr)
   png_debug(1, "in png_write_destroy");

   /* Free any memory zlib uses */
-   if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
+   if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
      deflateEnd(&png_ptr->zstream);

   /* Free our memory.  png_free checks NULL for us. */
@@ -1004,7 +1005,7 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
      return;

 #ifdef PNG_MNG_FEATURES_SUPPORTED
-   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+   if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
       (method == PNG_INTRAPIXEL_DIFFERENCING))
      method = PNG_FILTER_TYPE_BASE;

@@ -1055,14 +1056,16 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
      if (png_ptr->row_buf != NULL)
      {
 #ifdef PNG_WRITE_FILTER_SUPPORTED
-         if ((png_ptr->do_filter & PNG_FILTER_SUB) && png_ptr->sub_row == NULL)
+         if ((png_ptr->do_filter & PNG_FILTER_SUB) != 0 &&
+             png_ptr->sub_row == NULL)
         {
            png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
                (png_ptr->rowbytes + 1));
            png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
         }

-         if ((png_ptr->do_filter & PNG_FILTER_UP) && png_ptr->up_row == NULL)
+         if ((png_ptr->do_filter & PNG_FILTER_UP) != 0 &&
+              png_ptr->up_row == NULL)
         {
            if (png_ptr->prev_row == NULL)
            {
@@ -1079,7 +1082,8 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
            }
         }

-         if ((png_ptr->do_filter & PNG_FILTER_AVG) && png_ptr->avg_row == NULL)
+         if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0 &&
+              png_ptr->avg_row == NULL)
         {
            if (png_ptr->prev_row == NULL)
            {
@@ -1096,7 +1100,7 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
            }
         }

-         if ((png_ptr->do_filter & PNG_FILTER_PAETH) &&
+         if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0 &&
             png_ptr->paeth_row == NULL)
         {
            if (png_ptr->prev_row == NULL)
@@ -1257,7 +1261,7 @@ png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
   /* The internal API allocates all the arrays and ensures that the elements of
    * those arrays are set to the default value.
    */
-   if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
+   if (png_init_filter_heuristics(png_ptr, heuristic_method, num_weights) == 0)
      return;

   /* If using the weighted method copy in the weights. */
@@ -1312,7 +1316,7 @@ png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
   /* The internal API allocates all the arrays and ensures that the elements of
    * those arrays are set to the default value.
    */
-   if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
+   if (png_init_filter_heuristics(png_ptr, heuristic_method, num_weights) == 0)
      return;

   /* If using the weighted method copy in the weights. */
@@ -1571,7 +1575,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
   /* ------ these transformations don't touch the info structure ------- */

   /* Invert monochrome pixels */
-   if (transforms & PNG_TRANSFORM_INVERT_MONO)
+   if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
 #ifdef PNG_WRITE_INVERT_SUPPORTED
      png_set_invert_mono(png_ptr);
 #else
@@ -1581,16 +1585,16 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
   /* Shift the pixels up to a legal bit depth and fill in
    * as appropriate to correctly scale the image.
    */
-   if (transforms & PNG_TRANSFORM_SHIFT)
+   if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
 #ifdef PNG_WRITE_SHIFT_SUPPORTED
-      if (info_ptr->valid & PNG_INFO_sBIT)
+      if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
         png_set_shift(png_ptr, &info_ptr->sig_bit);
 #else
      png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
 #endif

   /* Pack pixels into bytes */
-   if (transforms & PNG_TRANSFORM_PACKING)
+   if ((transforms & PNG_TRANSFORM_PACKING) != 0)
 #ifdef PNG_WRITE_PACK_SUPPORTED
      png_set_packing(png_ptr);
 #else
@@ -1598,7 +1602,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

   /* Swap location of alpha bytes from ARGB to RGBA */
-   if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
+   if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
      png_set_swap_alpha(png_ptr);
 #else
@@ -1609,13 +1613,13 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
    * RGB, note that the code expects the input color type to be G or RGB; no
    * alpha channel.
    */
-   if (transforms &
-      (PNG_TRANSFORM_STRIP_FILLER_AFTER|PNG_TRANSFORM_STRIP_FILLER_BEFORE))
+   if ((transforms & (PNG_TRANSFORM_STRIP_FILLER_AFTER|
+      PNG_TRANSFORM_STRIP_FILLER_BEFORE)) != 0)
   {
 #ifdef PNG_WRITE_FILLER_SUPPORTED
-      if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
+      if ((transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER) != 0)
      {
-         if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
+         if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
            png_app_error(png_ptr,
               "PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");

@@ -1623,7 +1627,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
         png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
      }

-      else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
+      else if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
         png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 #else
      png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
@@ -1631,7 +1635,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
   }

   /* Flip BGR pixels to RGB */
-   if (transforms & PNG_TRANSFORM_BGR)
+   if ((transforms & PNG_TRANSFORM_BGR) != 0)
 #ifdef PNG_WRITE_BGR_SUPPORTED
      png_set_bgr(png_ptr);
 #else
@@ -1639,7 +1643,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

   /* Swap bytes of 16-bit files to most significant byte first */
-   if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
+   if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
 #ifdef PNG_WRITE_SWAP_SUPPORTED
      png_set_swap(png_ptr);
 #else
@@ -1647,7 +1651,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

   /* Swap bits of 1, 2, 4 bit packed pixel formats */
-   if (transforms & PNG_TRANSFORM_PACKSWAP)
+   if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
      png_set_packswap(png_ptr);
 #else
@@ -1655,7 +1659,7 @@ png_write_png(png_structrp png_ptr, png_inforp info_ptr,
 #endif

   /* Invert the alpha channel from opacity to transparency */
-   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
+   if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
      png_set_invert_alpha(png_ptr);
 #else
@@ -1746,14 +1750,14 @@ png_write_image_16bit(png_voidp argument)
      display->first_row);
   png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
   png_uint_16p row_end;
-   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
+   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
   int aindex = 0;
   png_uint_32 y = image->height;

-   if (image->format & PNG_FORMAT_FLAG_ALPHA)
+   if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
   {
 #     ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
-         if (image->format & PNG_FORMAT_FLAG_AFIRST)
+         if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
         {
            aindex = -1;
            ++input_row; /* To point to the first component */
@@ -1903,15 +1907,15 @@ png_write_image_8bit(png_voidp argument)
      display->first_row);
   png_bytep output_row = png_voidcast(png_bytep, display->local_row);
   png_uint_32 y = image->height;
-   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
+   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;

-   if (image->format & PNG_FORMAT_FLAG_ALPHA)
+   if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
   {
      png_bytep row_end;
      int aindex;

 #     ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
-         if (image->format & PNG_FORMAT_FLAG_AFIRST)
+         if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
         {
            aindex = -1;
            ++input_row; /* To point to the first component */
@@ -2008,7 +2012,7 @@ png_image_set_PLTE(png_image_write_control *display)
 #  endif

 #  ifdef PNG_FORMAT_BGR_SUPPORTED
-      const int bgr = (format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
+      const int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
 #  else
 #     define bgr 0
 #  endif
@@ -2025,13 +2029,13 @@ png_image_set_PLTE(png_image_write_control *display)
      /* This gets automatically converted to sRGB with reversal of the
       * pre-multiplication if the color-map has an alpha channel.
       */
-      if (format & PNG_FORMAT_FLAG_LINEAR)
+      if ((format & PNG_FORMAT_FLAG_LINEAR) != 0)
      {
         png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);

         entry += i * channels;

-         if (channels & 1) /* no alpha */
+         if ((channels & 1) != 0) /* no alpha */
         {
            if (channels >= 3) /* RGB */
            {
@@ -2143,12 +2147,11 @@ png_image_write_main(png_voidp argument)
   png_inforp info_ptr = image->opaque->info_ptr;
   png_uint_32 format = image->format;

-   int colormap = (format & PNG_FORMAT_FLAG_COLORMAP) != 0;
-   /* input */
-   int linear = (colormap == 0) && (format & PNG_FORMAT_FLAG_LINEAR) != 0;
-   int alpha = (colormap == 0) && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
-   int write_16bit = (linear != 0 ) && (colormap == 0) &&
-       (display->convert_to_8bit == 0);
+   /* The following four ints are actually booleans */
+   int colormap = (format & PNG_FORMAT_FLAG_COLORMAP);
+   int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR); /* input */
+   int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA);
+   int write_16bit = linear && !colormap && (display->convert_to_8bit == 0);

 #  ifdef PNG_BENIGN_ERRORS_SUPPORTED
      /* Make sure we error out on any bad situation */
@@ -2160,7 +2163,7 @@ png_image_write_main(png_voidp argument)
      display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);

   /* Set the required transforms then write the rows in the correct order. */
-   if (format & PNG_FORMAT_FLAG_COLORMAP)
+   if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0)
   {
      if (display->colormap != NULL && image->colormap_entries > 0)
      {
@@ -2197,7 +2200,7 @@ png_image_write_main(png_voidp argument)
      /* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
      png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);

-      if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
+      if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
         png_set_cHRM_fixed(png_ptr, info_ptr,
            /* color      x       y */
            /* white */ 31270, 32900,
@@ -2207,7 +2210,7 @@ png_image_write_main(png_voidp argument)
         );
   }

-   else if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
+   else if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
      png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);

   /* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
@@ -2228,12 +2231,12 @@ png_image_write_main(png_voidp argument)
   {
      PNG_CONST png_uint_16 le = 0x0001;

-      if (*(png_const_bytep)&le)
+      if ((*(png_const_bytep) & le) != 0)
         png_set_swap(png_ptr);
   }

 #  ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
-      if (format & PNG_FORMAT_FLAG_BGR)
+      if ((format & PNG_FORMAT_FLAG_BGR) != 0)
      {
         if (colormap == 0 && (format & PNG_FORMAT_FLAG_COLOR) != 0)
            png_set_bgr(png_ptr);
@@ -2242,7 +2245,7 @@ png_image_write_main(png_voidp argument)
 #  endif

 #  ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
-      if (format & PNG_FORMAT_FLAG_AFIRST)
+      if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
      {
         if (colormap == 0 && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
            png_set_swap_alpha(png_ptr);
@@ -2253,7 +2256,7 @@ png_image_write_main(png_voidp argument)
   /* If there are 16 or fewer color-map entries we wrote a lower bit depth
    * above, but the application data is still byte packed.
    */
-   if (colormap && image->colormap_entries <= 16)
+   if (colormap != 0 && image->colormap_entries <= 16)
      png_set_packing(png_ptr);

   /* That should have handled all (both) the transforms. */
@@ -2341,7 +2344,7 @@ png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
   {
      if (file != NULL)
      {
-         if (png_image_write_init(image))
+         if (png_image_write_init(image) != 0)
         {
            png_image_write_control display;
            int result;
@@ -2396,7 +2399,7 @@ png_image_write_to_file(png_imagep image, const char *file_name,
         if (fp != NULL)
         {
            if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
-               row_stride, colormap))
+               row_stride, colormap) != 0)
            {
               int error; /* from fflush/fclose */

--- 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 1.6.9 [February 6, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -177,7 +177,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
      int shift_start[4], shift_dec[4];
      int channels = 0;

-      if (row_info->color_type & PNG_COLOR_MASK_COLOR)
+      if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
      {
         shift_start[channels] = row_info->bit_depth - bit_depth->red;
         shift_dec[channels] = bit_depth->red;
@@ -199,7 +199,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
         channels++;
      }

-      if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
+      if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
      {
         shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
         shift_dec[channels] = bit_depth->alpha;
@@ -505,7 +505,7 @@ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
      return;

 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
-   if (png_ptr->transformations & PNG_USER_TRANSFORM)
+   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
      if (png_ptr->write_user_transform_fn != NULL)
         (*(png_ptr->write_user_transform_fn)) /* User write transform
                                                 function */
@@ -521,50 +521,50 @@ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
 #endif

 #ifdef PNG_WRITE_FILLER_SUPPORTED
-   if (png_ptr->transformations & PNG_FILLER)
+   if ((png_ptr->transformations & PNG_FILLER) != 0)
      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
         !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
 #endif

 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_PACKSWAP)
+   if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
      png_do_packswap(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_WRITE_PACK_SUPPORTED
-   if (png_ptr->transformations & PNG_PACK)
+   if ((png_ptr->transformations & PNG_PACK) != 0)
      png_do_pack(row_info, png_ptr->row_buf + 1,
          (png_uint_32)png_ptr->bit_depth);
 #endif

 #ifdef PNG_WRITE_SWAP_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
+   if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
      png_do_swap(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_WRITE_SHIFT_SUPPORTED
-   if (png_ptr->transformations & PNG_SHIFT)
+   if ((png_ptr->transformations & PNG_SHIFT) != 0)
      png_do_shift(row_info, png_ptr->row_buf + 1,
          &(png_ptr->shift));
 #endif

 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_SWAP_ALPHA)
+   if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
      png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_ALPHA)
+   if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
      png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_WRITE_BGR_SUPPORTED
-   if (png_ptr->transformations & PNG_BGR)
+   if ((png_ptr->transformations & PNG_BGR) != 0)
      png_do_bgr(row_info, png_ptr->row_buf + 1);
 #endif

 #ifdef PNG_WRITE_INVERT_SUPPORTED
-   if (png_ptr->transformations & PNG_INVERT_MONO)
+   if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
      png_do_invert(row_info, png_ptr->row_buf + 1);
 #endif
 }
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@

 /* pngwutil.c - utilities to write a PNG file
 *
- * Last changed in libpng 1.6.14 [October 23, 2014]
+ * Last changed in libpng 1.6.15 [(PENDING RELEASE)]
 * Copyright (c) 1998-2014 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.)
@@ -211,7 +211,7 @@ png_image_size(png_structrp png_ptr)

   if (png_ptr->rowbytes < 32768 && h < 32768)
   {
-      if (png_ptr->interlaced)
+      if (png_ptr->interlaced != 0)
      {
         /* Interlacing makes the image larger because of the replication of
          * both the filter byte and the padding to a byte boundary.
@@ -286,8 +286,6 @@ optimize_cmf(png_bytep data, png_alloc_size_t data_size)
      }
   }
 }
-#else
-#  define optimize_cmf(dp,dl) ((void)0)
 #endif /* PNG_WRITE_OPTIMIZE_CMF_SUPPORTED */

 /* Initialize the compressor for the appropriate type of compression. */
@@ -297,7 +295,7 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
 {
   if (png_ptr->zowner != 0)
   {
-#     if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
+#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED)
      char msg[64];

      PNG_STRING_FROM_CHUNK(msg, owner);
@@ -309,8 +307,8 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
       * are minimal.
       */
      (void)png_safecat(msg, (sizeof msg), 10, " using zstream");
-#     endif
-#     if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
+#endif
+#if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
         png_warning(png_ptr, msg);

         /* Attempt sane error recovery */
@@ -321,9 +319,9 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
         }

         png_ptr->zowner = 0;
-#     else
+#else
         png_error(png_ptr, msg);
-#     endif
+#endif
   }

   {
@@ -336,7 +334,7 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,

      if (owner == png_IDAT)
      {
-         if (png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY)
+         if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0)
            strategy = png_ptr->zlib_strategy;

         else if (png_ptr->do_filter != PNG_FILTER_NONE)
@@ -348,20 +346,20 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,

      else
      {
-#        ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
+#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
            level = png_ptr->zlib_text_level;
            method = png_ptr->zlib_text_method;
            windowBits = png_ptr->zlib_text_window_bits;
            memLevel = png_ptr->zlib_text_mem_level;
            strategy = png_ptr->zlib_text_strategy;
-#        else
+#else
            /* If customization is not supported the values all come from the
             * IDAT values except for the strategy, which is fixed to the
             * default.  (This is the pre-1.6.0 behavior too, although it was
             * implemented in a very different way.)
             */
            strategy = Z_DEFAULT_STRATEGY;
-#        endif
+#endif
      }

      /* Adjust 'windowBits' down if larger than 'data_size'; to stop this
@@ -388,7 +386,7 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
      }

      /* Check against the previous initialized values, if any. */
-      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) &&
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 &&
         (png_ptr->zlib_set_level != level ||
         png_ptr->zlib_set_method != method ||
         png_ptr->zlib_set_window_bits != windowBits ||
@@ -412,7 +410,7 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
      /* Now initialize if required, setting the new parameters, otherwise just
       * to a simple reset to the previous parameters.
       */
-      if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
+      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
         ret = deflateReset(&png_ptr->zstream);

      else
@@ -619,9 +617,10 @@ png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
       */
      if (ret == Z_STREAM_END && input_len == 0)
      {
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
         /* Fix up the deflate header, if required */
         optimize_cmf(comp->output, comp->input_len);
-
+#endif
         /* But Z_OK is returned, not Z_STREAM_END; this allows the claim
          * function above to return Z_STREAM_END on an error (though it never
          * does in the current versions of zlib.)
@@ -717,7 +716,7 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
         bad_character = ch; /* just skip it, record the first error */
   }

-   if (key_len > 0 && space) /* trailing space */
+   if (key_len > 0 && space != 0) /* trailing space */
   {
      --key_len, --new_key;
      if (bad_character == 0)
@@ -732,7 +731,7 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)

 #ifdef PNG_WARNINGS_SUPPORTED
   /* Try to only output one warning per keyword: */
-   if (*key) /* keyword too long */
+   if (*key != 0) /* keyword too long */
      png_warning(png_ptr, "keyword truncated");

   else if (bad_character != 0)
@@ -849,8 +848,8 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
    */
   if (
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
-       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
+       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
+       ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
       (color_type == PNG_COLOR_TYPE_RGB ||
        color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
       (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
@@ -931,7 +930,7 @@ png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,

   if ((
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-       !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
+       (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 &&
 #endif
       num_pal == 0) || num_pal > 256)
   {
@@ -947,7 +946,7 @@ png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
      }
   }

-   if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
+   if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
   {
      png_warning(png_ptr,
          "Ignoring request to write a PLTE chunk in grayscale PNG");
@@ -1074,11 +1073,11 @@ png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
         /* Write an IDAT containing the data then reset the buffer.  The
          * first IDAT may need deflate header optimization.
          */
-#        ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
-            if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
-               png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+            if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
+                png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
               optimize_cmf(data, png_image_size(png_ptr));
-#        endif
+#endif

         png_write_complete_chunk(png_ptr, png_IDAT, data, size);
         png_ptr->mode |= PNG_HAVE_IDAT;
@@ -1120,11 +1119,11 @@ png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
         png_bytep data = png_ptr->zbuffer_list->output;
         uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out;

-#        ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
-            if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
-               png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
-               optimize_cmf(data, png_image_size(png_ptr));
-#        endif
+#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
+         if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 &&
+             png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
+            optimize_cmf(data, png_image_size(png_ptr));
+#endif

         png_write_complete_chunk(png_ptr, png_IDAT, data, size);
         png_ptr->zstream.avail_out = 0;
@@ -1345,7 +1344,7 @@ png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
   png_debug(1, "in png_write_sBIT");

   /* Make sure we don't depend upon the order of PNG_COLOR_8 */
-   if (color_type & PNG_COLOR_MASK_COLOR)
+   if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      png_byte maxbits;

@@ -1378,7 +1377,7 @@ png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
      size = 1;
   }

-   if (color_type & PNG_COLOR_MASK_ALPHA)
+   if ((color_type & PNG_COLOR_MASK_ALPHA) != 0)
   {
      if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth)
      {
@@ -1465,9 +1464,9 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
      png_save_uint_16(buf + 2, tran->green);
      png_save_uint_16(buf + 4, tran->blue);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
-      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
+      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
 #else
-      if (buf[0] | buf[2] | buf[4])
+      if ((buf[0] | buf[2] | buf[4]) != 0)
 #endif
      {
         png_app_warning(png_ptr,
@@ -1498,8 +1497,8 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
   {
      if (
 #ifdef PNG_MNG_FEATURES_SUPPORTED
-          (png_ptr->num_palette ||
-          (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
+          (png_ptr->num_palette != 0 ||
+          (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
 #endif
         back->index >= png_ptr->num_palette)
      {
@@ -1511,15 +1510,15 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
   }

-   else if (color_type & PNG_COLOR_MASK_COLOR)
+   else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
      png_save_uint_16(buf, back->red);
      png_save_uint_16(buf + 2, back->green);
      png_save_uint_16(buf + 4, back->blue);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
-      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]))
+      if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0)
 #else
-      if (buf[0] | buf[2] | buf[4])
+      if ((buf[0] | buf[2] | buf[4]) != 0)
 #endif
      {
         png_warning(png_ptr,
@@ -1986,12 +1985,13 @@ png_write_start_row(png_structrp png_ptr)
   }

   /* We only need to keep the previous row if we are using one of these. */
-   if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
+   if ((png_ptr->do_filter &
+      (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0)
   {
      /* Set up previous row buffer */
      png_ptr->prev_row = (png_bytep)png_calloc(png_ptr, buf_size);

-      if (png_ptr->do_filter & PNG_FILTER_UP)
+      if ((png_ptr->do_filter & PNG_FILTER_UP) != 0)
      {
         png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
            png_ptr->rowbytes + 1);
@@ -1999,7 +1999,7 @@ png_write_start_row(png_structrp png_ptr)
         png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
      }

-      if (png_ptr->do_filter & PNG_FILTER_AVG)
+      if ((png_ptr->do_filter & PNG_FILTER_AVG) != 0)
      {
         png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
             png_ptr->rowbytes + 1);
@@ -2007,7 +2007,7 @@ png_write_start_row(png_structrp png_ptr)
         png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
      }

-      if (png_ptr->do_filter & PNG_FILTER_PAETH)
+      if ((png_ptr->do_filter & PNG_FILTER_PAETH) != 0)
      {
         png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
             png_ptr->rowbytes + 1);
@@ -2019,9 +2019,9 @@ png_write_start_row(png_structrp png_ptr)

 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
   /* If interlaced, we need to set up width and height of pass */
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
   {
-      if (!(png_ptr->transformations & PNG_INTERLACE))
+      if ((png_ptr->transformations & PNG_INTERLACE) == 0)
      {
         png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
             png_pass_ystart[0]) / png_pass_yinc[0];
@@ -2076,10 +2076,10 @@ png_write_finish_row(png_structrp png_ptr)

 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
   /* If interlaced, go to next pass */
-   if (png_ptr->interlaced)
+   if (png_ptr->interlaced != 0)
   {
      png_ptr->row_number = 0;
-      if (png_ptr->transformations & PNG_INTERLACE)
+      if ((png_ptr->transformations & PNG_INTERLACE) != 0)
      {
         png_ptr->pass++;
      }
@@ -2104,7 +2104,7 @@ png_write_finish_row(png_structrp png_ptr)
                png_pass_ystart[png_ptr->pass]) /
                png_pass_yinc[png_ptr->pass];

-            if (png_ptr->transformations & PNG_INTERLACE)
+            if ((png_ptr->transformations & PNG_INTERLACE) != 0)
               break;

         } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
@@ -2383,7 +2383,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   /* We don't need to test the 'no filter' case if this is the only filter
    * that has been chosen, as it doesn't actually do anything to the data.
    */
-   if ((filter_to_do & PNG_FILTER_NONE) && filter_to_do != PNG_FILTER_NONE)
+   if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
   {
      png_bytep rp;
      png_uint_32 sum = 0;
@@ -2459,7 +2459,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
      best_row = png_ptr->sub_row;
   }

-   else if (filter_to_do & PNG_FILTER_SUB)
+   else if ((filter_to_do & PNG_FILTER_SUB) != 0)
   {
      png_bytep rp, dp, lp;
      png_uint_32 sum = 0, lmins = mins;
@@ -2580,7 +2580,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
      best_row = png_ptr->up_row;
   }

-   else if (filter_to_do & PNG_FILTER_UP)
+   else if ((filter_to_do & PNG_FILTER_UP) != 0)
   {
      png_bytep rp, dp, pp;
      png_uint_32 sum = 0, lmins = mins;
@@ -2694,7 +2694,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
      best_row = png_ptr->avg_row;
   }

-   else if (filter_to_do & PNG_FILTER_AVG)
+   else if ((filter_to_do & PNG_FILTER_AVG) != 0)
   {
      png_bytep rp, dp, pp, lp;
      png_uint_32 sum = 0, lmins = mins;
@@ -2796,7 +2796,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   }

   /* Paeth filter */
-   if (filter_to_do == PNG_FILTER_PAETH)
+   if ((filter_to_do == PNG_FILTER_PAETH) != 0)
   {
      png_bytep rp, dp, pp, cp, lp;
      png_size_t i;
@@ -2835,7 +2835,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
      best_row = png_ptr->paeth_row;
   }

-   else if (filter_to_do & PNG_FILTER_PAETH)
+   else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
   {
      png_bytep rp, dp, pp, cp, lp;
      png_uint_32 sum = 0, lmins = mins;
--- a/projects/vstudio/readme.txt
+++ b/projects/vstudio/readme.txt
@@ -1,7 +1,7 @@

 VisualStudio instructions

-libpng version 1.6.15beta01 - October 29, 2014
+libpng version 1.6.15beta04 - November 4, 2014

 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 1.6.15beta01 - October 29, 2014
+ * libpng version 1.6.15beta04 - November 4, 2014
 *
 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
 *
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@

-Makefiles for  libpng version 1.6.15beta01 - October 29, 2014
+Makefiles for  libpng version 1.6.15beta04 - November 4, 2014

 pnglibconf.h.prebuilt       =>  Stores configuration settings
 makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.15beta01)
+                       (gcc, creates libpng16.so.16.1.6.15beta04)
 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.16.1.6.15beta01)
+                       creates libpng16.so.16.1.6.15beta04)
 makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
 makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.15beta01)
+                       creates libpng16.so.16.1.6.15beta04)
 makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.15beta01)
+                       creates libpng16.so.16.1.6.15beta04)
 makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
 makefile.sunos    =>  Sun makefile
 makefile.32sunu   =>  Sun Ultra 32-bit makefile
--- a/scripts/def.dfn
+++ b/scripts/def.dfn
@@ -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 1.6.15beta01"
+PNG_DFN ";Version 1.6.15beta04"

 #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=1.6.15beta01
+version=1.6.15beta04
 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: 1.6.15beta01
+Version: 1.6.15beta04
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@ INCSDIR=${LOCALBASE}/include/libpng16

 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.15beta01
+SHLIB_MINOR=	1.6.15beta04
 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=	1.6.15beta01
+SHLIB_MINOR=	1.6.15beta04
 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=	1.6.15beta01
+SHLIB_MINOR=	1.6.15beta04

 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
--- a/scripts/pnglibconf.dfa
+++ b/scripts/pnglibconf.dfa
@@ -221,7 +221,7 @@ option SET_OPTION disabled
 # ARM_NEON_API:   (PNG_ARM_NEON == 1) allow the optimization to be switched on
 #                 with png_set_option
 # ARM_NEON_CHECK: (PNG_ARM_NEON == 1) compile a run-time check to see if Neon
-#                 extensions are supported, this is poorly supported and
+#                 extensions are supported. This is poorly supported and
 #                 deprectated - use the png_set_option API.
 setting ARM_NEON_OPT
 option ARM_NEON_API disabled requires ALIGNED_MEMORY enables SET_OPTION,
--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.15beta01 STANDARD API DEFINITION */
+/* libpng 1.6.15beta04 STANDARD API DEFINITION */

 /* pnglibconf.h - library build configuration */

-/* Libpng version 1.6.15beta01 - October 29, 2014 */
+/* Libpng version 1.6.15beta04 - November 4, 2014 */

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

--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.15beta01
+;Version 1.6.15beta04
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng
Author	SHA1	Message	Date
Glenn Randers-Pehrson	b5113f4e70	[libpng16] Imported from libpng-1.6.15beta04.tar	2014-11-04 07:08:23 -06:00
John Bowler	445475a166	[libpng16] Removed new PNG_USE_ARM_NEON configuration flag and made a one-line revision to configure.ac to support ARM on aarch64 instead (John Bowler).	2014-11-03 19:44:39 -06:00
Glenn Randers-Pehrson	2eb712e519	[libpng16] Bump version to 1.6.15beta04	2014-11-03 09:33:51 -06:00
Glenn Randers-Pehrson	736c8e8773	[libpng16] Imported from libpng-1.6.15beta03.tar	2014-11-03 09:33:44 -06:00
Glenn Randers-Pehrson	3278452323	[libpng16] Added PNG_USE_ARM_NEON configuration flag (Marcin Juszkiewicz).	2014-11-03 08:24:34 -06:00
Glenn Randers-Pehrson	bd3818eb1b	[libpng16] Bump version to 1.6.15beta03	2014-11-01 18:59:15 -05:00
Glenn Randers-Pehrson	b75c3cc415	[libpng16] Imported from libpng-1.6.15beta02.tar	2014-11-01 18:59:08 -05:00
Glenn Randers-Pehrson	b963feeec6	[libpng16] More cosmetic changes	2014-11-01 13:18:36 -05:00
Glenn Randers-Pehrson	f2d4167fee	[libpng16] Added a pair of parentheses suggested by clang	2014-10-31 21:17:11 -05:00
Glenn Randers-Pehrson	5d713fe123	[libpng16] Changed remaining "if (!x)" to "if (x == 0)" and "if (x)" to "if (x !== 0)"	2014-10-31 20:58:40 -05:00
Glenn Randers-Pehrson	6b9a20e7f9	[libpng16] Bump version to 1.6.15beta02	2014-10-29 09:13:06 -05:00