Imported from libpng-1.4.0beta61.tarv1.4.0beta61

32 files changed, 370 insertions, 346 deletions

diff --git a/ANNOUNCE b/ANNOUNCE
index cc9ffbc39..e355a4bf6 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.4.0beta61 - May 18, 2009
+Libpng 1.4.0beta61 - May 20, 2009
 
 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.
@@ -454,12 +454,18 @@ version 1.4.0beta59 [May 15, 2009]
     documentation
   Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
 
-version 1.4.0beta60 [May 18, 2009]
+version 1.4.0beta60 [May 19, 2009]
   Conditionally compile png_read_finish_row() which is not used by
     progressive readers.
   Added contrib/pngminim/preader to demonstrate building minimal progressive
     decoder, based on contrib/gregbook with embedded libpng and zlib.
 
+version 1.4.0beta61 [May 20, 2009]
+  In contrib/pngminim/*, renamed "makefile.std" to "makefile", since there
+    is only one makefile in those directories, and revised the README files
+    accordingly.
+  More reformatting of comments, mostly to capitalize sentences.
+
 version 1.4.0betaN [future]
   Build shared libraries with -lz and sometimes -lm.
 
diff --git a/CHANGES b/CHANGES
index a16af78ce..cce74c791 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2131,12 +2131,18 @@ version 1.4.0beta59 [May 15, 2009]
     documentation
   Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
 
-version 1.4.0beta60 [May 18, 2009]
+version 1.4.0beta60 [May 19, 2009]
   Conditionally compile png_read_finish_row() which is not used by
     progressive readers.
   Added contrib/pngminim/preader to demonstrate building minimal progressive
     decoder, based on contrib/gregbook with embedded libpng and zlib.
 
+version 1.4.0beta61 [May 20, 2009]
+  In contrib/pngminim/*, renamed "makefile.std" to "makefile", since there
+    is only one makefile in those directories, and revised the README files
+    accordingly.
+  More reformatting of comments, mostly to capitalize sentences.
+
 version 1.4.0betaN [future]
   Build shared libraries with -lz and sometimes -lm.
 
diff --git a/INSTALL b/INSTALL
index 8ba551fde..ad9f307b2 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,5 +1,5 @@
 
-Installing libpng version 1.4.0beta61 - May 18, 2009
+Installing libpng version 1.4.0beta61 - May 20, 2009
 
 On Unix/Linux and similar systems, you can simply type
 
diff --git a/LICENSE b/LICENSE
index 8124dcd23..c90aa02c0 100644
--- a/LICENSE
+++ b/LICENSE
@@ -8,7 +8,7 @@ COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
 If you modify libpng you may insert additional notices immediately following
 this sentence.
 
-libpng versions 1.2.6, August 15, 2004, through 1.4.0beta61, May 18, 2009, are
+libpng versions 1.2.6, August 15, 2004, through 1.4.0beta61, May 20, 2009, are
 Copyright (c) 2004, 2006-2007 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
@@ -106,4 +106,4 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 18, 2009
+May 20, 2009
diff --git a/README b/README
index 2aaf50a0d..f424b99f2 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-README for libpng version 1.4.0beta61 - May 18, 2009 (shared library 14.0)
+README for libpng version 1.4.0beta61 - May 20, 2009 (shared library 14.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
diff --git a/contrib/pngminim/decoder/README b/contrib/pngminim/decoder/README
index 981b60b1f..a656e0b93 100644
--- a/contrib/pngminim/decoder/README
+++ b/contrib/pngminim/decoder/README
@@ -1,7 +1,9 @@
 This demonstrates the use of PNG_USER_CONFIG and pngusr.h
 
-To build a minimal read-only decoder, run
+To build a minimal read-only decoder with embedded libpng and zlib, run
 
     gather.sh  # to collect needed files from pngminus, libpng, and zlib
     make
- 
+
+If you prefer to use the shared libraries, go to contrib/pngminus
+and build the png2pnm application there. 
diff --git a/contrib/pngminim/encoder/README b/contrib/pngminim/encoder/README
index 3a44f13b1..2285544f4 100644
--- a/contrib/pngminim/encoder/README
+++ b/contrib/pngminim/encoder/README
@@ -1,7 +1,9 @@
 This demonstrates the use of PNG_USER_CONFIG and pngusr.h
 
-To build a minimal write-only encoder, run
+To build a minimal write-only decoder with embedded libpng and zlib, run
 
     gather.sh  # to collect needed files from pngminus, libpng, and zlib
     make
  
+If you prefer to use the shared libraries, go to contrib/pngminus
+and build the pnm2png application there. 
diff --git a/contrib/pngminim/preader/README b/contrib/pngminim/preader/README
index 33239dd0e..377d641ad 100644
--- a/contrib/pngminim/preader/README
+++ b/contrib/pngminim/preader/README
@@ -1,6 +1,7 @@
 This demonstrates the use of PNG_USER_CONFIG and pngusr.h
 
-To build a minimal read-only progressive decoder with X display, run
+To build a minimal read-only progressive decoder embedded libpng and
+zlib and with your system's X library, run
 
     gather.sh # to collect needed files from gregbook, libpng, and zlib
 
@@ -9,3 +10,5 @@ then
     
     make
  
+If you prefer to use the shared libraries, go to contrib/gregbook
+and build the rpng2-x application there. 
diff --git a/example.c b/example.c
index cd4b7656a..623a39c78 100644
--- 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 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * This file has been placed in the public domain by the authors.
  * Maintained 1998-2009 Glenn Randers-Pehrson
  * Maintained 1996, 1997 Andreas Dilger)
@@ -93,13 +93,13 @@ void read_png(char *file_name)  /* We need to open the file */
       return (ERROR);
 
 #else no_open_file /* prototype 2 */
-void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
+void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */
 {
    png_structp png_ptr;
    png_infop info_ptr;
    png_uint_32 width, height;
    int bit_depth, color_type, interlace_type;
-#endif no_open_file /* only use one prototype! */
+#endif no_open_file /* Only use one prototype! */
 
    /* Create and initialize the png_struct with the desired error handler
     * functions.  If you want to use the default stderr and longjump method,
@@ -280,7 +280,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
       png_colorp palette;
 
       /* This reduces the image to the application supplied palette */
-      if (/* we have our own palette */)
+      if (/* We have our own palette */)
       {
          /* An array of colors to which the image should be dithered */
          png_color std_color_cube[MAX_SCREEN_COLORS];
@@ -377,13 +377,13 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 #else no_sparkle /* Read the image using the "rectangle" effect */
          png_read_rows(png_ptr, NULL, &row_pointers[y],
             number_of_rows);
-#endif no_sparkle /* use only one of these two methods */
+#endif no_sparkle /* Use only one of these two methods */
       }
 
-      /* if you want to display the image after every pass, do so here */
-#endif no_single /* use only one of these two methods */
+      /* If you want to display the image after every pass, do so here */
+#endif no_single /* Use only one of these two methods */
    }
-#endif no_entire /* use only one of these two methods */
+#endif no_entire /* Use only one of these two methods */
 
    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
@@ -397,7 +397,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    /* Close the file */
    fclose(fp);
 
-   /* that's it */
+   /* That's it */
    return (OK);
 }
 
@@ -621,7 +621,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
       user_IO_flush_function);
    /* where user_io_ptr is a structure you want available to the callbacks */
-#endif no_streams /* only use one initialization method */
+#endif no_streams /* Only use one initialization method */
 
 #ifdef hilevel
    /* This is the easy way.  Use it if you already have all the
@@ -773,7 +773,7 @@ void write_png(char *file_name /* , ... other image information ... */)
 #ifdef entire /* Write out the entire image data in one call */
    png_write_image(png_ptr, row_pointers);
 
-   /* the other way to write the image - deal with interlacing */
+   /* The other way to write the image - deal with interlacing */
 
 #else no_entire /* Write out the image data by one or more scanlines */
 
diff --git a/libpng-1.4.0beta61.txt b/libpng-1.4.0beta61.txt
index 007eb50b8..89ffac6ef 100644
--- a/libpng-1.4.0beta61.txt
+++ b/libpng-1.4.0beta61.txt
@@ -1,6 +1,6 @@
 libpng.txt - A description on how to use and modify libpng
 
- libpng version 1.4.0beta61 - May 18, 2009
+ libpng version 1.4.0beta61 - May 20, 2009
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
@@ -9,7 +9,7 @@ libpng.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.4.0beta61 - May 18, 2009
+ libpng versions 0.97, January 1998, through 1.4.0beta61 - May 20, 2009
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
 
@@ -3151,7 +3151,7 @@ source.
 
 XII. Y2K Compliance in libpng
 
-May 18, 2009
+May 20, 2009
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
diff --git a/libpng.3 b/libpng.3
index d04702118..3f5091679 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,4 +1,4 @@
-.TH LIBPNG 3 "May 18, 2009"
+.TH LIBPNG 3 "May 20, 2009"
 .SH NAME
 libpng \- Portable Network Graphics (PNG) Reference Library 1.4.0beta61
 .SH SYNOPSIS
@@ -809,7 +809,7 @@ Following is a copy of the libpng.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng.txt - A description on how to use and modify libpng
 
- libpng version 1.4.0beta61 - May 18, 2009
+ libpng version 1.4.0beta61 - May 20, 2009
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
@@ -818,7 +818,7 @@ libpng.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.4.0beta61 - May 18, 2009
+ libpng versions 0.97, January 1998, through 1.4.0beta61 - May 20, 2009
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
 
@@ -3960,7 +3960,7 @@ source.
 
 .SH XII. Y2K Compliance in libpng
 
-May 18, 2009
+May 20, 2009
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
@@ -4190,7 +4190,7 @@ possible without all of you.
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.4.0beta61 - May 18, 2009:
+Libpng version 1.4.0beta61 - May 20, 2009:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -4211,7 +4211,7 @@ included in the libpng distribution, the latter shall prevail.)
 If you modify libpng you may insert additional notices immediately following
 this sentence.
 
-libpng versions 1.2.6, August 15, 2004, through 1.4.0beta61, May 18, 2009, are
+libpng versions 1.2.6, August 15, 2004, through 1.4.0beta61, May 20, 2009, are
 Copyright (c) 2004,2006-2007 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
@@ -4310,7 +4310,7 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-May 18, 2009
+May 20, 2009
 
 .\" end of man page
 
diff --git a/libpngpf.3 b/libpngpf.3
index 379ed7561..d32db1175 100644
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,4 +1,4 @@
-.TH LIBPNGPF 3 "May 18, 2009"
+.TH LIBPNGPF 3 "May 20, 2009"
 .SH NAME
 libpng \- Portable Network Graphics (PNG) Reference Library 1.4.0beta61
 (private functions)
diff --git a/png.5 b/png.5
index 9d37436ae..bf270b6b3 100644
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "May 18, 2009"
+.TH PNG 5 "May 20, 2009"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
diff --git a/png.c b/png.c
index 28d6b46ec..15cb1f186 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -53,18 +53,18 @@ PNG_tRNS;
 PNG_zTXt;
 
 #ifdef PNG_READ_SUPPORTED
-/* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+/* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-/* start of interlace block */
+/* Start of interlace block */
 PNG_CONST int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
 
-/* offset to next interlace block */
+/* Offset to next interlace block */
 PNG_CONST int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
 
-/* start of interlace block in the y direction */
+/* Start of interlace block in the y direction */
 PNG_CONST int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
 
-/* offset to next interlace block in the y direction */
+/* Offset to next interlace block in the y direction */
 PNG_CONST int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
 
 /* Height of interlace block.  This is not currently used - if you need
@@ -155,7 +155,7 @@ png_zalloc(voidpf png_ptr, uInt items, uInt size)
    return ((voidpf)ptr);
 }
 
-/* function to free memory for zlib */
+/* Function to free memory for zlib */
 void /* private */
 png_zfree(voidpf png_ptr, voidpf ptr)
 {
@@ -275,7 +275,7 @@ png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
       *ptr_ptr = info_ptr;
    }
 
-   /* set everything to 0 */
+   /* Set everything to 0 */
    png_memset(info_ptr, 0, png_sizeof(png_info));
 }
 
@@ -306,7 +306,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
       return;
 
 #if defined(PNG_TEXT_SUPPORTED)
-   /* free text item num or (if num == -1) all text items */
+   /* Free text item num or (if num == -1) all text items */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
 #else
@@ -334,7 +334,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #if defined(PNG_tRNS_SUPPORTED)
-   /* free any tRNS entry */
+   /* Free any tRNS entry */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
 #else
@@ -351,7 +351,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #if defined(PNG_sCAL_SUPPORTED)
-   /* free any sCAL entry */
+   /* Free any sCAL entry */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
 #else
@@ -369,7 +369,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #if defined(PNG_pCAL_SUPPORTED)
-   /* free any pCAL entry */
+   /* Free any pCAL entry */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
 #else
@@ -396,7 +396,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #if defined(PNG_iCCP_SUPPORTED)
-   /* free any iCCP entry */
+   /* Free any iCCP entry */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
 #else
@@ -412,7 +412,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #if defined(PNG_sPLT_SUPPORTED)
-   /* free a given sPLT entry, or (if num == -1) all sPLT entries */
+   /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
 #else
@@ -485,7 +485,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
 #endif
 
 #if defined(PNG_hIST_SUPPORTED)
-   /* free any hIST entry */
+   /* Free any hIST entry */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
 #else
@@ -501,7 +501,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
    }
 #endif
 
-   /* free any PLTE entry that was internally allocated */
+   /* Free any PLTE entry that was internally allocated */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
 #else
@@ -518,7 +518,7 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
    }
 
 #if defined(PNG_INFO_IMAGE_SUPPORTED)
-   /* free any image bits attached to the info structure */
+   /* Free any image bits attached to the info structure */
 #ifdef PNG_FREE_ME_SUPPORTED
    if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
 #else
@@ -643,19 +643,19 @@ png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
 png_charp PNGAPI
 png_get_copyright(png_structp png_ptr)
 {
-   png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
+   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 #ifdef PNG_STRING_COPYRIGHT
       return PNG_STRING_COPYRIGHT
 #else
 #ifdef __STDC__
    return ((png_charp) PNG_STRING_NEWLINE \
-     "libpng version x 1.4.0beta61 - May 18, 2009" PNG_STRING_NEWLINE \
+     "libpng version x 1.4.0beta61 - May 20, 2009" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2009 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 ((png_charp) "libpng version 1.4.0beta61 - May 18, 2009\
+      return ((png_charp) "libpng version 1.4.0beta61 - May 20, 2009\
       Copyright (c) 1998-2009 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.");
@@ -675,7 +675,7 @@ png_charp PNGAPI
 png_get_libpng_ver(png_structp png_ptr)
 {
    /* Version of *.c files used when building libpng */
-   png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
+   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
    return ((png_charp) PNG_LIBPNG_VER_STRING);
 }
 
@@ -683,7 +683,7 @@ png_charp PNGAPI
 png_get_header_ver(png_structp png_ptr)
 {
    /* Version of *.h files used when building libpng */
-   png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
+   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
    return ((png_charp) PNG_LIBPNG_VER_STRING);
 }
 
@@ -691,7 +691,7 @@ png_charp PNGAPI
 png_get_header_version(png_structp png_ptr)
 {
    /* Returns longer string containing both version and date */
-   png_ptr = png_ptr;  /* silence compiler warning about unused png_ptr */
+   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
 #ifdef __STDC__
    return ((png_charp) PNG_HEADER_VERSION_STRING
 #ifndef PNG_READ_SUPPORTED
@@ -708,7 +708,7 @@ png_get_header_version(png_structp png_ptr)
 int PNGAPI
 png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
 {
-   /* check chunk_name and return "keep" value if it's on the list, else 0 */
+   /* Check chunk_name and return "keep" value if it's on the list, else 0 */
    int i;
    png_bytep p;
    if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list<=0)
diff --git a/png.h b/png.h
index 8f5b9beef..4bf45f51b 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.4.0beta61 - May 18, 2009
+ * libpng version 1.4.0beta61 - May 20, 2009
  * Copyright (c) 1998-2009 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.)
@@ -9,7 +9,7 @@
  * 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 1.4.0beta61 - May 18, 2009: Glenn
+ *  libpng versions 0.97, January 1998, through 1.4.0beta61 - May 20, 2009: Glenn
  *  See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -157,7 +157,7 @@
  * If you modify libpng you may insert additional notices immediately following
  * this sentence.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.4.0beta61, May 18, 2009, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.4.0beta61, May 20, 2009, are
  * Copyright (c) 2004, 2006-2007 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:
@@ -333,7 +333,7 @@
 /* Version information for png.h - this should match the version in png.c */
 #define PNG_LIBPNG_VER_STRING "1.4.0beta61"
 #define PNG_HEADER_VERSION_STRING \
-   " libpng version 1.4.0beta61 - May 18, 2009\n"
+   " libpng version 1.4.0beta61 - May 20, 2009\n"
 
 #define PNG_LIBPNG_VER_SONUM   14
 #define PNG_LIBPNG_VER_DLLNUM  14
diff --git a/pngconf.h b/pngconf.h
index 4f64322e9..29792ecfa 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.4.0beta61 - May 18, 2009
+ * libpng version 1.4.0beta61 - May 20, 2009
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngerror.c b/pngerror.c
index 606764284..d2b46c13a 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,7 +1,7 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -39,37 +39,37 @@ png_error(png_structp 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))
+     {
        if (*error_message == PNG_LITERAL_SHARP)
-         {
-            /* Strip "#nnnn " from beginning of error message. */
-            int offset;
-            for (offset = 1; offset<15; offset++)
-               if (error_message[offset] == ' ')
-                   break;
-            if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
-            {
-               int i;
-               for (i = 0; i < offset - 1; i++)
-                  msg[i] = error_message[i + 1];
-               msg[i - 1] = '\0';
-               error_message = msg;
-            }
-            else
-               error_message += offset;
-         }
-         else
-         {
-            if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
-            {
-               msg[0] = '0';
-               msg[1] = '\0';
-               error_message = msg;
-            }
-         }
-      }
+       {
+           /* Strip "#nnnn " from beginning of error message. */
+           int offset;
+           for (offset = 1; offset<15; offset++)
+              if (error_message[offset] == ' ')
+                  break;
+           if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+           {
+              int i;
+              for (i = 0; i < offset - 1; i++)
+                 msg[i] = error_message[i + 1];
+              msg[i - 1] = '\0';
+              error_message = msg;
+           }
+           else
+              error_message += offset;
+       }
+       else
+       {
+           if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT)
+           {
+              msg[0] = '0';
+              msg[1] = '\0';
+              error_message = msg;
+           }
+       }
+     }
    }
 #endif
    if (png_ptr != NULL && png_ptr->error_fn != NULL)
@@ -108,14 +108,14 @@ png_warning(png_structp png_ptr, png_const_charp warning_message)
    if (png_ptr->flags&
      (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))
 #endif
-      {
-         if (*warning_message == PNG_LITERAL_SHARP)
-         {
-            for (offset = 1; offset < 15; offset++)
-               if (warning_message[offset] == ' ')
-                   break;
-         }
-      }
+     {
+       if (*warning_message == PNG_LITERAL_SHARP)
+       {
+           for (offset = 1; offset < 15; offset++)
+              if (warning_message[offset] == ' ')
+                  break;
+       }
+     }
    }
    if (png_ptr != NULL && png_ptr->warning_fn != NULL)
       (*(png_ptr->warning_fn))(png_ptr, warning_message + offset);
@@ -128,10 +128,10 @@ png_warning(png_structp png_ptr, png_const_charp warning_message)
 void PNGAPI
 png_benign_error(png_structp png_ptr, png_const_charp error_message)
 {
-   if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
-      png_warning(png_ptr, error_message);
-   else
-      png_error(png_ptr, error_message);
+  if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+    png_warning(png_ptr, error_message);
+  else
+    png_error(png_ptr, error_message);
 }
 #endif
 
@@ -189,11 +189,11 @@ png_chunk_error(png_structp png_ptr, png_const_charp error_message)
 {
    char msg[18+PNG_MAX_ERROR_TEXT];
    if (png_ptr == NULL)
-      png_error(png_ptr, error_message);
+     png_error(png_ptr, error_message);
    else
    {
-      png_format_buffer(png_ptr, msg, error_message);
-      png_error(png_ptr, msg);
+     png_format_buffer(png_ptr, msg, error_message);
+     png_error(png_ptr, msg);
    }
 }
 #endif /* PNG_READ_SUPPORTED */
@@ -205,11 +205,11 @@ png_chunk_warning(png_structp png_ptr, png_const_charp warning_message)
 {
    char msg[18+PNG_MAX_ERROR_TEXT];
    if (png_ptr == NULL)
-      png_warning(png_ptr, warning_message);
+     png_warning(png_ptr, warning_message);
    else
    {
-      png_format_buffer(png_ptr, msg, warning_message);
-      png_warning(png_ptr, msg);
+     png_format_buffer(png_ptr, msg, warning_message);
+     png_warning(png_ptr, msg);
    }
 }
 #endif /* PNG_NO_WARNINGS */
@@ -219,10 +219,10 @@ png_chunk_warning(png_structp png_ptr, png_const_charp warning_message)
 void PNGAPI
 png_chunk_benign_error(png_structp png_ptr, png_const_charp error_message)
 {
-   if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
-      png_chunk_warning(png_ptr, error_message);
-   else
-      png_chunk_error(png_ptr, error_message);
+  if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN)
+    png_chunk_warning(png_ptr, error_message);
+  else
+    png_chunk_error(png_ptr, error_message);
 }
 #endif
 #endif /* PNG_READ_SUPPORTED */
@@ -239,28 +239,28 @@ png_default_error(png_structp png_ptr, png_const_charp error_message)
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
    if (*error_message == PNG_LITERAL_SHARP)
    {
-      /* Strip "#nnnn " from beginning of error message. */
-      int offset;
-      char error_number[16];
-      for (offset = 0; offset<15; offset++)
-      {
+     /* Strip "#nnnn " from beginning of error message. */
+     int offset;
+     char error_number[16];
+     for (offset = 0; offset<15; offset++)
+     {
          error_number[offset] = error_message[offset + 1];
          if (error_message[offset] == ' ')
              break;
-      }
-      if ((offset > 1) && (offset < 15))
-      {
-         error_number[offset - 1] = '\0';
-         fprintf(stderr, "libpng error no. %s: %s",
-            error_number, error_message + offset + 1);
-         fprintf(stderr, PNG_STRING_NEWLINE);
-      }
-      else
-      {
-        fprintf(stderr, "libpng error: %s, offset=%d",
-           error_message, offset);
-        fprintf(stderr, PNG_STRING_NEWLINE);
-      }
+     }
+     if ((offset > 1) && (offset < 15))
+     {
+       error_number[offset - 1] = '\0';
+       fprintf(stderr, "libpng error no. %s: %s",
+          error_number, error_message + offset + 1);
+       fprintf(stderr, PNG_STRING_NEWLINE);
+     }
+     else
+     {
+       fprintf(stderr, "libpng error: %s, offset=%d",
+          error_message, offset);
+       fprintf(stderr, PNG_STRING_NEWLINE);
+     }
    }
    else
 #endif
@@ -287,7 +287,7 @@ png_default_error(png_structp png_ptr, png_const_charp error_message)
    PNG_ABORT();
 #endif
 #ifdef PNG_NO_CONSOLE_IO
-   error_message = error_message; /* make compiler happy */
+   error_message = error_message; /* Make compiler happy */
 #endif
 }
 
@@ -304,38 +304,38 @@ png_default_warning(png_structp png_ptr, png_const_charp warning_message)
 #  ifdef PNG_ERROR_NUMBERS_SUPPORTED
    if (*warning_message == PNG_LITERAL_SHARP)
    {
-      int offset;
-      char warning_number[16];
-      for (offset = 0; offset < 15; offset++)
-      {
-         warning_number[offset] = warning_message[offset + 1];
-         if (warning_message[offset] == ' ')
+     int offset;
+     char warning_number[16];
+     for (offset = 0; offset < 15; offset++)
+     {
+        warning_number[offset] = warning_message[offset + 1];
+        if (warning_message[offset] == ' ')
             break;
-      }
-      if ((offset > 1) && (offset < 15))
-      {
-         warning_number[offset + 1] = '\0';
-         fprintf(stderr, "libpng warning no. %s: %s",
-            warning_number, warning_message + offset);
-         fprintf(stderr, PNG_STRING_NEWLINE);
-      }
-      else
-      {
-         fprintf(stderr, "libpng warning: %s",
-            warning_message);
-         fprintf(stderr, PNG_STRING_NEWLINE);
-      }
+     }
+     if ((offset > 1) && (offset < 15))
+     {
+       warning_number[offset + 1] = '\0';
+       fprintf(stderr, "libpng warning no. %s: %s",
+          warning_number, warning_message + offset);
+       fprintf(stderr, PNG_STRING_NEWLINE);
+     }
+     else
+     {
+       fprintf(stderr, "libpng warning: %s",
+          warning_message);
+       fprintf(stderr, PNG_STRING_NEWLINE);
+     }
    }
    else
 #  endif
    {
-      fprintf(stderr, "libpng warning: %s", warning_message);
-      fprintf(stderr, PNG_STRING_NEWLINE);
+     fprintf(stderr, "libpng warning: %s", warning_message);
+     fprintf(stderr, PNG_STRING_NEWLINE);
    }
 #else
-   warning_message = warning_message; /* make compiler happy */
+   warning_message = warning_message; /* Make compiler happy */
 #endif
-   png_ptr = png_ptr; /* make compiler happy */
+   png_ptr = png_ptr; /* Make compiler happy */
 }
 #endif /* PNG_NO_WARNINGS */
 
@@ -375,7 +375,7 @@ png_set_strip_error_numbers(png_structp png_ptr, png_uint_32 strip_mode)
 {
    if (png_ptr != NULL)
    {
-      png_ptr->flags &=
+     png_ptr->flags &=
        ((~(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
    }
 }
diff --git a/pngget.c b/pngget.c
index b5b9c3ea1..8a7d0ef00 100644
--- a/pngget.c
+++ b/pngget.c
@@ -1,7 +1,7 @@
 
 /* pngget.c - retrieval of values from info struct
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -510,8 +510,9 @@ png_get_iCCP(png_structp png_ptr, png_infop info_ptr,
       png_debug1(1, "in %s retrieval function", "iCCP");
       *name = info_ptr->iccp_name;
       *profile = info_ptr->iccp_profile;
-      /* compression_type is a dummy so the API won't have to change
-         if we introduce multiple compression types later. */
+      /* Compression_type is a dummy so the API won't have to change
+       * if we introduce multiple compression types later.
+       */
       *proflen = (int)info_ptr->iccp_proflen;
       *compression_type = (int)info_ptr->iccp_compression;
       return (PNG_INFO_iCCP);
diff --git a/pngmem.c b/pngmem.c
index 3bbcc2a6f..96dcab2dd 100644
--- a/pngmem.c
+++ b/pngmem.c
@@ -1,7 +1,7 @@
 
 /* pngmem.c - stub functions for memory allocation
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -20,7 +20,7 @@
 
 /* Borland DOS special memory handler */
 #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
-/* if you change this, be sure to change the one in png.h also */
+/* If you change this, be sure to change the one in png.h also */
 
 /* Allocate memory for a png_struct.  The malloc and memset can be replaced
    by a single call to calloc() if this is thought to improve performance. */
@@ -166,7 +166,7 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
    {
       if (png_ptr->offset_table == NULL)
       {
-         /* try to see if we need to do any of this fancy stuff */
+         /* Try to see if we need to do any of this fancy stuff */
          ret = farmalloc(size);
          if (ret == NULL || ((png_size_t)ret & 0xffff))
          {
@@ -281,7 +281,7 @@ png_malloc_default(png_structp png_ptr, png_alloc_size_t size)
    return (ret);
 }
 
-/* free a pointer allocated by png_malloc().  In the default
+/* Free a pointer allocated by png_malloc().  In the default
  * configuration, png_ptr is not used, but is passed in case it
  * is needed.  If ptr is NULL, return without taking any action.
  */
diff --git a/pngpread.c b/pngpread.c
index af28e3645..d849c09e6 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,7 +12,7 @@
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 #include "pngpriv.h"
 
-/* push model modes */
+/* Push model modes */
 #define PNG_READ_SIG_MODE   0
 #define PNG_READ_CHUNK_MODE 1
 #define PNG_READ_IDAT_MODE  2
@@ -762,7 +762,7 @@ png_push_read_IDAT(png_structp png_ptr)
       {
          save_size = (png_size_t)png_ptr->idat_size;
 
-         /* check for overflow */
+         /* Check for overflow */
          if ((png_uint_32)save_size != png_ptr->idat_size)
             png_error(png_ptr, "save_size overflowed in pngpread");
       }
@@ -787,7 +787,7 @@ png_push_read_IDAT(png_structp png_ptr)
       {
          save_size = (png_size_t)png_ptr->idat_size;
 
-         /* check for overflow */
+         /* Check for overflow */
          if ((png_uint_32)save_size != png_ptr->idat_size)
             png_error(png_ptr, "save_size overflowed in pngpread");
       }
@@ -899,7 +899,7 @@ png_push_process_row(png_structp png_ptr)
       png_do_read_transformations(png_ptr);
 
 #if defined(PNG_READ_INTERLACING_SUPPORTED)
-   /* blow up interlaced rows to full size */
+   /* Blow up interlaced rows to full size */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       if (png_ptr->pass < 6)
@@ -917,10 +917,10 @@ png_push_process_row(png_structp png_ptr)
             for (i = 0; i < 8 && png_ptr->pass == 0; i++)
             {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
-               png_read_push_finish_row(png_ptr); /* updates png_ptr->pass */
+               png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
             }
 
-            if (png_ptr->pass == 2) /* pass 1 might be empty */
+            if (png_ptr->pass == 2) /* Pass 1 might be empty */
             {
                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                {
@@ -956,7 +956,7 @@ png_push_process_row(png_structp png_ptr)
                png_read_push_finish_row(png_ptr);
             }
 
-            if (png_ptr->pass == 2) /* skip top 4 generated rows */
+            if (png_ptr->pass == 2) /* Skip top 4 generated rows */
             {
                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                {
@@ -984,7 +984,7 @@ png_push_process_row(png_structp png_ptr)
                png_read_push_finish_row(png_ptr);
             }
 
-            if (png_ptr->pass == 4) /* pass 3 might be empty */
+            if (png_ptr->pass == 4) /* Pass 3 might be empty */
             {
                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
@@ -1006,7 +1006,7 @@ png_push_process_row(png_structp png_ptr)
                png_read_push_finish_row(png_ptr);
             }
 
-            if (png_ptr->pass == 4) /* skip top two generated rows */
+            if (png_ptr->pass == 4) /* Skip top two generated rows */
             {
                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
@@ -1034,7 +1034,7 @@ png_push_process_row(png_structp png_ptr)
                png_read_push_finish_row(png_ptr);
             }
 
-            if (png_ptr->pass == 6) /* pass 5 might be empty */
+            if (png_ptr->pass == 6) /* Pass 5 might be empty */
             {
                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
@@ -1053,7 +1053,7 @@ png_push_process_row(png_structp png_ptr)
                png_read_push_finish_row(png_ptr);
             }
 
-            if (png_ptr->pass == 6) /* skip top generated row */
+            if (png_ptr->pass == 6) /* Skip top generated row */
             {
                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
@@ -1159,7 +1159,7 @@ png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
       {
          png_error(png_ptr, "Out of place tEXt");
-         info_ptr = info_ptr; /* to quiet some compiler warnings */
+         info_ptr = info_ptr; /* To quiet some compiler warnings */
       }
 
 #ifdef PNG_MAX_MALLOC_64K
@@ -1222,7 +1222,7 @@ png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr)
       key = png_ptr->current_text;
 
       for (text = key; *text; text++)
-         /* empty loop */ ;
+         /* Empty loop */ ;
 
       if (text < key + png_ptr->current_text_size)
          text++;
@@ -1257,7 +1257,7 @@ png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
       {
          png_error(png_ptr, "Out of place zTXt");
-         info_ptr = info_ptr; /* to quiet some compiler warnings */
+         info_ptr = info_ptr; /* To quiet some compiler warnings */
       }
 
 #ifdef PNG_MAX_MALLOC_64K
@@ -1318,7 +1318,7 @@ png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
       key = png_ptr->current_text;
 
       for (text = key; *text; text++)
-         /* empty loop */ ;
+         /* Empty loop */ ;
 
       /* zTXt can't have zero text */
       if (text >= key + png_ptr->current_text_size)
@@ -1330,7 +1330,7 @@ png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
 
       text++;
 
-      if (*text != PNG_TEXT_COMPRESSION_zTXt) /* check compression byte */
+      if (*text != PNG_TEXT_COMPRESSION_zTXt) /* Check compression byte */
       {
          png_ptr->current_text = NULL;
          png_free(png_ptr, key);
@@ -1458,7 +1458,7 @@ png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
       {
          png_error(png_ptr, "Out of place iTXt");
-         info_ptr = info_ptr; /* to quiet some compiler warnings */
+         info_ptr = info_ptr; /* To quiet some compiler warnings */
       }
 
 #ifdef PNG_MAX_MALLOC_64K
@@ -1525,25 +1525,25 @@ png_push_read_iTXt(png_structp png_ptr, png_infop info_ptr)
       key = png_ptr->current_text;
 
       for (lang = key; *lang; lang++)
-         /* empty loop */ ;
+         /* Empty loop */ ;
 
       if (lang < key + png_ptr->current_text_size - 3)
          lang++;
 
       comp_flag = *lang++;
-      lang++;     /* skip comp_type, always zero */
+      lang++;     /* Skip comp_type, always zero */
 
       for (lang_key = lang; *lang_key; lang_key++)
-         /* empty loop */ ;
+         /* Empty loop */ ;
 
-      lang_key++;        /* skip NUL separator */
+      lang_key++;        /* Skip NUL separator */
 
       text=lang_key;
 
       if (lang_key < key + png_ptr->current_text_size - 1)
       {
         for (; *text; text++)
-           /* empty loop */ ;
+           /* Empty loop */ ;
       }
 
       if (text < key + png_ptr->current_text_size)
@@ -1593,7 +1593,7 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
 #endif
          png_chunk_error(png_ptr, "unknown critical chunk");
 
-      info_ptr = info_ptr; /* to quiet some compiler warnings */
+      info_ptr = info_ptr; /* To quiet some compiler warnings */
    }
 
 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
@@ -1628,7 +1628,7 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
       if (png_ptr->read_user_chunk_fn != NULL)
       {
-         /* callback to user unknown chunk handler */
+         /* Callback to user unknown chunk handler */
          int ret;
          ret = (*(png_ptr->read_user_chunk_fn))
            (png_ptr, &png_ptr->unknown_chunk);
diff --git a/pngpriv.h b/pngpriv.h
index f03b27e98..7cf62e773 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1,7 +1,7 @@
 
 /* pngpriv.h - private declarations for use inside libpng
  *
- * libpng version 1.4.0beta61 - May 18, 2009
+ * libpng version 1.4.0beta61 - May 20, 2009
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngread.c b/pngread.c
index 174cd2eac..d5d0067e7 100644
--- a/pngread.c
+++ b/pngread.c
@@ -1,7 +1,7 @@
 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngrio.c b/pngrio.c
index 00b875046..c06dfe06d 100644
--- a/pngrio.c
+++ b/pngrio.c
@@ -1,7 +1,7 @@
 
 /* pngrio.c - functions for data input
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngrtran.c b/pngrtran.c
index 06c5c8fd8..89422245a 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1,7 +1,7 @@
 
 /* pngrtran.c - transforms the data in a row for PNG readers
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -27,24 +27,24 @@ png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
       return;
    switch (crit_action)
    {
-      case PNG_CRC_NO_CHANGE:                        /* leave setting as is */
+      case PNG_CRC_NO_CHANGE:                        /* Leave setting as is */
          break;
 
-      case PNG_CRC_WARN_USE:                               /* warn/use data */
+      case PNG_CRC_WARN_USE:                               /* Warn/use data */
          png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
          png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
          break;
 
-      case PNG_CRC_QUIET_USE:                             /* quiet/use data */
+      case PNG_CRC_QUIET_USE:                             /* Quiet/use data */
          png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
          png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
                            PNG_FLAG_CRC_CRITICAL_IGNORE;
          break;
 
-      case PNG_CRC_WARN_DISCARD:    /* not a valid action for critical data */
+      case PNG_CRC_WARN_DISCARD:    /* Not a valid action for critical data */
          png_warning(png_ptr,
             "Can't discard critical data on CRC error");
-      case PNG_CRC_ERROR_QUIT:                                /* error/quit */
+      case PNG_CRC_ERROR_QUIT:                                /* Error/quit */
 
       case PNG_CRC_DEFAULT:
       default:
@@ -54,26 +54,26 @@ png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
 
    switch (ancil_action)
    {
-      case PNG_CRC_NO_CHANGE:                       /* leave setting as is */
+      case PNG_CRC_NO_CHANGE:                       /* Leave setting as is */
          break;
 
-      case PNG_CRC_WARN_USE:                              /* warn/use data */
+      case PNG_CRC_WARN_USE:                              /* Warn/use data */
          png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
          png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
          break;
 
-      case PNG_CRC_QUIET_USE:                            /* quiet/use data */
+      case PNG_CRC_QUIET_USE:                            /* Quiet/use data */
          png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
          png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
                            PNG_FLAG_CRC_ANCILLARY_NOWARN;
          break;
 
-      case PNG_CRC_ERROR_QUIT:                               /* error/quit */
+      case PNG_CRC_ERROR_QUIT:                               /* Error/quit */
          png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
          png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
          break;
 
-      case PNG_CRC_WARN_DISCARD:                      /* warn/discard data */
+      case PNG_CRC_WARN_DISCARD:                      /* Warn/discard data */
 
       case PNG_CRC_DEFAULT:
       default:
@@ -84,7 +84,7 @@ png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
     defined(PNG_FLOATING_POINT_SUPPORTED)
-/* handle alpha and tRNS via a background color */
+/* Handle alpha and tRNS via a background color */
 void PNGAPI
 png_set_background(png_structp png_ptr,
    png_color_16p background_color, int background_gamma_code,
@@ -195,11 +195,11 @@ png_set_dither(png_structp png_ptr, png_colorp palette,
 
          int i;
 
-         /* initialize an array to sort colors */
+         /* Initialize an array to sort colors */
          png_ptr->dither_sort = (png_bytep)png_malloc(png_ptr,
             (png_uint_32)(num_palette * png_sizeof(png_byte)));
 
-         /* initialize the dither_sort array */
+         /* Initialize the dither_sort array */
          for (i = 0; i < num_palette; i++)
             png_ptr->dither_sort[i] = (png_byte)i;
 
@@ -212,7 +212,7 @@ png_set_dither(png_structp png_ptr, png_colorp palette,
 
          for (i = num_palette - 1; i >= maximum_colors; i--)
          {
-            int done; /* to stop early if the list is pre-sorted */
+            int done; /* To stop early if the list is pre-sorted */
             int j;
 
             done = 1;
@@ -885,7 +885,7 @@ png_init_read_transformations(png_structp png_ptr)
     for (i=0; i<png_ptr->num_trans; i++)
     {
       if (png_ptr->trans[i] != 0 && png_ptr->trans[i] != 0xff)
-        k=1; /* partial transparency is present */
+        k=1; /* Partial transparency is present */
     }
     if (k == 0)
       png_ptr->transformations &= ~PNG_GAMMA;
@@ -1066,7 +1066,7 @@ png_init_read_transformations(png_structp png_ptr)
          }
       }
       else
-      /* transformation does not include PNG_BACKGROUND */
+      /* Transformation does not include PNG_BACKGROUND */
 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
       if (color_type == PNG_COLOR_TYPE_PALETTE)
       {
@@ -1528,7 +1528,7 @@ png_do_read_transformations(png_structp png_ptr)
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
     {
       if (png_ptr->read_user_transform_fn != NULL)
-         (*(png_ptr->read_user_transform_fn)) /* user read transform function */
+         (*(png_ptr->read_user_transform_fn)) /* User read transform function */
             (png_ptr,                    /* png_ptr */
                &(png_ptr->row_info),     /* row_info: */
                /*  png_uint_32 width;       width of row */
@@ -2242,7 +2242,7 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
 #endif
 
 #if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
-/* expand grayscale files to RGB, with or without alpha */
+/* Expand grayscale files to RGB, with or without alpha */
 void /* PRIVATE */
 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 {
@@ -2322,7 +2322,7 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 #endif
 
 #if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-/* reduce RGB files to grayscale, with or without alpha
+/* Reduce RGB files to grayscale, with or without alpha
  * using the equation given in Poynton's ColorFAQ at
  * <http://www.inforamp.net/~poynton/>  (THIS LINK IS DEAD June 2008)
  * New link:
@@ -4009,7 +4009,7 @@ png_build_gamma_table(png_structp png_ptr)
            g = 1.0 / png_ptr->screen_gamma;
 
         else
-           g = png_ptr->gamma;   /* probably doing rgb_to_gray */
+           g = png_ptr->gamma;   /* Probably doing rgb_to_gray */
 
         for (i = 0; i < 256; i++)
         {
@@ -4164,7 +4164,7 @@ png_build_gamma_table(png_structp png_ptr)
            g = 1.0 / png_ptr->screen_gamma;
 
         else
-           g = png_ptr->gamma;   /* probably doing rgb_to_gray */
+           g = png_ptr->gamma;   /* Probably doing rgb_to_gray */
 
 #ifdef PNG_CALLOC_SUPPORTED
         png_ptr->gamma_16_from_1 = (png_uint_16pp)png_calloc(png_ptr,
@@ -4200,7 +4200,7 @@ png_build_gamma_table(png_structp png_ptr)
 #endif
 
 #if defined(PNG_MNG_FEATURES_SUPPORTED)
-/* undoes intrapixel differencing  */
+/* Undoes intrapixel differencing  */
 void /* PRIVATE */
 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
 {
diff --git a/pngrutil.c b/pngrutil.c
index 71f517663..932b25740 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -179,7 +179,7 @@ png_crc_error(png_structp png_ptr)
    }
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* inform the I/O callback that the chunk CRC is being read */
+   /* Inform the I/O callback that the chunk CRC is being read */
    /* PNG_IO_CHUNK_CRC requires the I/O to be done at once */
    png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_CRC;
 #endif
@@ -523,7 +523,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_byte buf[3];
 
       png_crc_read(png_ptr, buf, 3);
-      /* don't depend upon png_color being any order */
+      /* Don't depend upon png_color being any order */
       palette[i].red = buf[0];
       palette[i].green = buf[1];
       palette[i].blue = buf[2];
@@ -609,7 +609,7 @@ png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
    png_crc_finish(png_ptr, length);
 
-   info_ptr = info_ptr; /* quiet compiler warnings about unused info_ptr */
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 }
 
 #if defined(PNG_READ_gAMA_SUPPORTED)
@@ -659,7 +659,7 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
 
    igamma = (png_fixed_point)png_get_uint_32(buf);
-   /* check for zero gamma */
+   /* Check for zero gamma */
    if (igamma == 0)
       {
          png_warning(png_ptr,
@@ -923,7 +923,7 @@ png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
 
    intent = buf[0];
-   /* check for bad intent */
+   /* Check for bad intent */
    if (intent >= PNG_sRGB_INTENT_LAST)
    {
       png_warning(png_ptr, "Unknown sRGB intent");
@@ -1038,12 +1038,13 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_ptr->chunkdata[slength] = 0x00;
 
    for (profile = png_ptr->chunkdata; *profile; profile++)
-      /* empty loop to find end of name */ ;
+      /* Empty loop to find end of name */ ;
 
    ++profile;
 
-   /* there should be at least one zero (the compression type byte)
-      following the separator, and we should be on it  */
+   /* There should be at least one zero (the compression type byte)
+    * following the separator, and we should be on it
+    */
    if ( profile >= png_ptr->chunkdata + slength - 1)
    {
       png_free(png_ptr, png_ptr->chunkdata);
@@ -1052,7 +1053,7 @@ png_handle_iCCP(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   /* compression_type should always be zero */
+   /* Compression_type should always be zero */
    compression_type = *profile++;
    if (compression_type)
    {
@@ -1167,10 +1168,10 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_ptr->chunkdata[slength] = 0x00;
 
    for (entry_start = (png_bytep)png_ptr->chunkdata; *entry_start; entry_start++)
-      /* empty loop to find end of name */ ;
+      /* Empty loop to find end of name */ ;
    ++entry_start;
 
-   /* a sample depth should follow the separator, and we should be on it  */
+   /* A sample depth should follow the separator, and we should be on it  */
    if (entry_start > (png_bytep)png_ptr->chunkdata + slength - 2)
    {
       png_free(png_ptr, png_ptr->chunkdata);
@@ -1183,7 +1184,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    entry_size = (new_palette.depth == 8 ? 6 : 10);
    data_length = (slength - (entry_start - (png_bytep)png_ptr->chunkdata));
 
-   /* integrity-check the data length */
+   /* Integrity-check the data length */
    if (data_length % entry_size)
    {
       png_free(png_ptr, png_ptr->chunkdata);
@@ -1251,7 +1252,7 @@ png_handle_sPLT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 #endif
 
-   /* discard all chunk data except the name and stash that */
+   /* Discard all chunk data except the name and stash that */
    new_palette.name = png_ptr->chunkdata;
 
    png_set_sPLT(png_ptr, info_ptr, &new_palette, 1);
@@ -1587,7 +1588,7 @@ png_handle_oFFs(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
 #if defined(PNG_READ_pCAL_SUPPORTED)
-/* read the pCAL chunk (described in the PNG Extensions document) */
+/* Read the pCAL chunk (described in the PNG Extensions document) */
 void /* PRIVATE */
 png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -1634,11 +1635,11 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_ptr->chunkdata[slength] = 0x00; /* null terminate the last string */
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
    png_debug(3, "Finding end of pCAL purpose string");
    for (buf = png_ptr->chunkdata; *buf; buf++)
-      /* empty loop */ ;
+      /* Empty loop */ ;
 
    endptr = png_ptr->chunkdata + slength;
 
@@ -1721,7 +1722,7 @@ png_handle_pCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
 #if defined(PNG_READ_sCAL_SUPPORTED)
-/* read the sCAL chunk */
+/* Read the sCAL chunk */
 void /* PRIVATE */
 png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -1771,9 +1772,9 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
 
-   png_ptr->chunkdata[slength] = 0x00; /* null terminate the last string */
+   png_ptr->chunkdata[slength] = 0x00; /* Null terminate the last string */
 
-   ep = png_ptr->chunkdata + 1;        /* skip unit byte */
+   ep = png_ptr->chunkdata + 1;        /* Skip unit byte */
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    width = png_strtod(png_ptr, ep, &vp);
@@ -1795,7 +1796,7 @@ png_handle_sCAL(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
    for (ep = png_ptr->chunkdata; *ep; ep++)
-      /* empty loop */ ;
+      /* Empty loop */ ;
    ep++;
 
    if (png_ptr->chunkdata + slength < ep)
@@ -1975,7 +1976,7 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    key[slength] = 0x00;
 
    for (text = key; *text; text++)
-      /* empty loop to find end of key */ ;
+      /* Empty loop to find end of key */ ;
 
    if (text != key + slength)
       text++;
@@ -2010,7 +2011,7 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
 #if defined(PNG_READ_zTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -2075,7 +2076,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_ptr->chunkdata[slength] = 0x00;
 
    for (text = png_ptr->chunkdata; *text; text++)
-      /* empty loop */ ;
+      /* Empty loop */ ;
 
    /* zTXt must have some text after the chunkdataword */
    if (text >= png_ptr->chunkdata + slength - 2)
@@ -2093,7 +2094,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
           png_warning(png_ptr, "Unknown compression type in zTXt chunk");
           comp_type = PNG_TEXT_COMPRESSION_zTXt;
        }
-       text++;        /* skip the compression_method byte */
+       text++;        /* Skip the compression_method byte */
    }
    prefix_len = text - png_ptr->chunkdata;
 
@@ -2130,7 +2131,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #endif
 
 #if defined(PNG_READ_iTXt_SUPPORTED)
-/* note: this does not correctly handle chunks that are > 64K under DOS */
+/* Note: this does not correctly handle chunks that are > 64K under DOS */
 void /* PRIVATE */
 png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -2196,12 +2197,13 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_ptr->chunkdata[slength] = 0x00;
 
    for (lang = png_ptr->chunkdata; *lang; lang++)
-      /* empty loop */ ;
-   lang++;        /* skip NUL separator */
+      /* Empty loop */ ;
+   lang++;        /* Skip NUL separator */
 
    /* iTXt must have a language tag (possibly empty), two compression bytes,
-      translated keyword (possibly empty), and possibly some text after the
-      keyword */
+    * translated keyword (possibly empty), and possibly some text after the
+    * keyword
+    */
 
    if (lang >= png_ptr->chunkdata + slength - 3)
    {
@@ -2217,8 +2219,8 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    for (lang_key = lang; *lang_key; lang_key++)
-      /* empty loop */ ;
-   lang_key++;        /* skip NUL separator */
+      /* Empty loop */ ;
+   lang_key++;        /* Skip NUL separator */
 
    if (lang_key >= png_ptr->chunkdata + slength)
    {
@@ -2229,8 +2231,8 @@ png_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    for (text = lang_key; *text; text++)
-      /* empty loop */ ;
-   text++;        /* skip NUL separator */
+      /* Empty loop */ ;
+   text++;        /* Skip NUL separator */
    if (text >= png_ptr->chunkdata + slength)
    {
       png_warning(png_ptr, "Malformed iTXt chunk");
@@ -2308,7 +2310,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_USE_LOCAL_ARRAYS
       PNG_CONST PNG_IDAT;
 #endif
-      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* not an IDAT */
+      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))  /* Not an IDAT */
          png_ptr->mode |= PNG_AFTER_IDAT;
    }
 
@@ -2352,7 +2354,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #if defined(PNG_READ_USER_CHUNKS_SUPPORTED)
        if (png_ptr->read_user_chunk_fn != NULL)
        {
-          /* callback to user unknown chunk handler */
+          /* Callback to user unknown chunk handler */
           int ret;
           ret = (*(png_ptr->read_user_chunk_fn))
             (png_ptr, &png_ptr->unknown_chunk);
@@ -2381,7 +2383,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    png_crc_finish(png_ptr, skip);
 
 #if !defined(PNG_READ_USER_CHUNKS_SUPPORTED)
-   info_ptr = info_ptr; /* quiet compiler warnings about unused info_ptr */
+   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
 #endif
 }
 
@@ -2629,8 +2631,8 @@ png_do_read_interlace(png_structp png_ptr)
    int pass = png_ptr->pass;
    png_uint_32 transformations = png_ptr->transformations;
 #ifdef PNG_USE_LOCAL_ARRAYS
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
-   /* offset to next interlace block */
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Offset to next interlace block */
    PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 #endif
 
@@ -2838,7 +2840,7 @@ png_do_read_interlace(png_structp png_ptr)
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, final_width);
    }
 #if !defined(PNG_READ_PACKSWAP_SUPPORTED)
-   transformations = transformations; /* silence compiler warning */
+   transformations = transformations; /* Silence compiler warning */
 #endif
 }
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
@@ -2922,7 +2924,7 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
             rp++;
          }
 
-         for (i = 0; i < istop; i++)   /* use leftover rp,pp */
+         for (i = 0; i < istop; i++)   /* Use leftover rp,pp */
          {
             int a, b, c, pa, pb, pc, p;
 
@@ -2972,18 +2974,18 @@ png_read_finish_row(png_structp png_ptr)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-   /* start of interlace block */
+   /* Start of interlace block */
    PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
-   /* offset to next interlace block */
+   /* Offset to next interlace block */
    PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   /* start of interlace block in the y direction */
+   /* Start of interlace block in the y direction */
    PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
-   /* offset to next interlace block in the y direction */
+   /* Offset to next interlace block in the y direction */
    PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif /* PNG_READ_INTERLACING_SUPPORTED */
 #endif
@@ -3105,18 +3107,18 @@ png_read_start_row(png_structp png_ptr)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* arrays to facilitate easy interlacing - use pass (0 - 6) as index */
+   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
-   /* start of interlace block */
+   /* Start of interlace block */
    PNG_CONST int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
-   /* offset to next interlace block */
+   /* Offset to next interlace block */
    PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
-   /* start of interlace block in the y direction */
+   /* Start of interlace block in the y direction */
    PNG_CONST int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
-   /* offset to next interlace block in the y direction */
+   /* Offset to next interlace block in the y direction */
    PNG_CONST int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
 #endif
@@ -3253,11 +3255,13 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
      }
 #endif
 
-   /* align the width on the next larger 8 pixels.  Mainly used
-      for interlacing */
+   /* Align the width on the next larger 8 pixels.  Mainly used
+    * for interlacing
+    */
    row_bytes = ((png_ptr->width + 7) & ~((png_uint_32)7));
-   /* calculate the maximum bytes needed, adding a byte and a pixel
-      for safety's sake */
+   /* Calculate the maximum bytes needed, adding a byte and a pixel
+    * for safety's sake
+    */
    row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
       1 + ((max_pixel_depth + 7) >> 3);
 #ifdef PNG_MAX_MALLOC_64K
diff --git a/pngset.c b/pngset.c
index c5a6d8895..686f6ca54 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -221,7 +221,7 @@ png_set_IHDR(png_structp png_ptr, png_infop info_ptr,
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   /* check for width and height valid values */
+   /* Check for width and height valid values */
    if (width == 0 || height == 0)
       png_error(png_ptr, "Image width or height is zero in IHDR");
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
@@ -241,7 +241,7 @@ png_set_IHDR(png_structp png_ptr, png_infop info_ptr,
                  - 8)       /* extra max_pixel_depth pad */
       png_warning(png_ptr, "Width is too large for libpng to process pixels");
 
-   /* check other values */
+   /* Check other values */
    if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
       bit_depth != 8 && bit_depth != 16)
       png_error(png_ptr, "Invalid bit depth in IHDR");
@@ -307,7 +307,7 @@ png_set_IHDR(png_structp png_ptr, png_infop info_ptr,
       info_ptr->channels++;
    info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);
 
-   /* check for potential overflow */
+   /* Check for potential overflow */
    if (width > (PNG_UINT_32_MAX
                  >> 3)      /* 8-byte RGBA pixels */
                  - 64       /* bigrowbuf hack */
@@ -774,7 +774,7 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
       else
 #ifdef PNG_iTXt_SUPPORTED
       {
-         /* set iTXt data */
+         /* Set iTXt data */
          if (text_ptr[i].lang != NULL)
             lang_len = png_strlen(text_ptr[i].lang);
          else
@@ -1044,7 +1044,7 @@ png_set_unknown_chunks(png_structp png_ptr,
                  png_sizeof(from->name));
       to->name[png_sizeof(to->name)-1] = '\0';
       to->size = from->size;
-      /* note our location in the read or write sequence */
+      /* Note our location in the read or write sequence */
       to->location = (png_byte)(png_ptr->mode & 0xff);
 
       if (from->size == 0)
@@ -1196,7 +1196,7 @@ png_set_invalid(png_structp png_ptr, png_infop info_ptr, int mask)
 
 
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
-/* this function was added to libpng 1.2.6 */
+/* This function was added to libpng 1.2.6 */
 void PNGAPI
 png_set_user_limits (png_structp png_ptr, png_uint_32 user_width_max,
     png_uint_32 user_height_max)
@@ -1210,7 +1210,7 @@ png_set_user_limits (png_structp png_ptr, png_uint_32 user_width_max,
    png_ptr->user_width_max = user_width_max;
    png_ptr->user_height_max = user_height_max;
 }
-/* this function was added to libpng 1.4.0 */
+/* This function was added to libpng 1.4.0 */
 void PNGAPI
 png_set_chunk_cache_max (png_structp png_ptr,
    png_uint_32 user_chunk_cache_max)
diff --git a/pngtest.c b/pngtest.c
index 0f17b608e..0dc8f40e8 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -1,7 +1,7 @@
 
 /* pngtest.c - a simple test program to test libpng
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -45,7 +45,7 @@
 #endif
 
 #if !PNG_DEBUG
-#  define SINGLE_ROWBUF_ALLOC  /* makes buffer overruns easier to nail */
+#  define SINGLE_ROWBUF_ALLOC  /* Makes buffer overruns easier to nail */
 #endif
 
 /* Turn on CPU timing
@@ -75,9 +75,9 @@ int test_one_file PNGARG((PNG_CONST char *inname, PNG_CONST char *outname));
 #include <mem.h>
 #endif
 
-/* defined so I can write to a file on gui/windowing platforms */
+/* Defined so I can write to a file on gui/windowing platforms */
 /*  #define STDERR stderr  */
-#define STDERR stdout   /* for DOS */
+#define STDERR stdout   /* For DOS */
 
 /* In case a system header (e.g., on AIX) defined jmpbuf */
 #ifdef jmpbuf
@@ -89,7 +89,7 @@ int test_one_file PNGARG((PNG_CONST char *inname, PNG_CONST char *outname));
 #  define png_jmpbuf(png_ptr) png_ptr->jmpbuf
 #endif
 
-/* example of using row callbacks to make a simple progress meter */
+/* Example of using row callbacks to make a simple progress meter */
 static int status_pass = 1;
 static int status_dots_requested = 0;
 static int status_dots = 1;
@@ -144,7 +144,7 @@ count_filters(png_structp png_ptr, png_row_infop row_info, png_bytep data)
 #endif
 
 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
-/* example of using user transform callback (we don't transform anything,
+/* Example of using user transform callback (we don't transform anything,
  * but merely count the zero samples)
  */
 
@@ -158,7 +158,7 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
    png_bytep dp = data;
    if (png_ptr == NULL)return;
 
-   /* contents of row_info:
+   /* Contents of row_info:
     *  png_uint_32 width      width of row
     *  png_uint_32 rowbytes   number of bytes in row
     *  png_byte color_type    color type of pixels
@@ -167,7 +167,7 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
     *  png_byte pixel_depth   bits per pixel (depth*channels)
     */
 
-    /* counts the number of zero samples (or zero pixels if color_type is 3 */
+    /* Counts the number of zero samples (or zero pixels if color_type is 3 */
 
     if (row_info->color_type == 0 || row_info->color_type == 3)
     {
@@ -215,7 +215,7 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
           }
        }
     }
-    else /* other color types */
+    else /* Other color types */
     {
        png_uint_32 n, nstop;
        int channel;
@@ -307,7 +307,7 @@ pngtest_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
       {
          read = MIN(NEAR_BUF_SIZE, remaining);
          err = fread(buf, 1, 1, io_ptr);
-         png_memcpy(data, buf, read); /* copy far buffer to near buffer */
+         png_memcpy(data, buf, read); /* Copy far buffer to near buffer */
          if (err != read)
             break;
          else
@@ -327,7 +327,7 @@ static void
 pngtest_flush(png_structp png_ptr)
 {
    /* Do nothing; fflush() is said to be just a waste of energy. */
-   png_ptr = png_ptr;  /* stifle compiler warning */
+   png_ptr = png_ptr;  /* Stifle compiler warning */
 }
 #endif
 
@@ -380,7 +380,7 @@ pngtest_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
       do
       {
          written = MIN(NEAR_BUF_SIZE, remaining);
-         png_memcpy(buf, data, written); /* copy far buffer to near buffer */
+         png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
          err = fwrite(buf, 1, written, io_ptr);
          if (err != written)
             break;
@@ -884,8 +884,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_set_gAMA(write_ptr, write_info_ptr, gamma);
    }
 #endif
-#endif /* floating point */
-#endif /* fixed point */
+#endif /* Floating point */
+#endif /* Fixed point */
 #if defined(PNG_iCCP_SUPPORTED)
    {
       png_charp name;
@@ -1025,7 +1025,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       {
          png_set_tIME(write_ptr, write_info_ptr, mod_time);
 #if defined(PNG_TIME_RFC1123_SUPPORTED)
-         /* we have to use png_memcpy instead of "=" because the string
+         /* We have to use png_memcpy instead of "=" because the string
           * pointed to by png_convert_to_rfc1123() gets free'ed before
           * we use it.
           */
@@ -1070,7 +1070,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_size_t i;
          png_set_unknown_chunks(write_ptr, write_info_ptr, unknowns,
            num_unknowns);
-         /* copy the locations from the read_info_ptr.  The automatically
+         /* Copy the locations from the read_info_ptr.  The automatically
           * generated locations in write_info_ptr are wrong because we
           * haven't written anything yet.
           */
@@ -1213,7 +1213,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
       {
          png_set_tIME(write_ptr, write_end_info_ptr, mod_time);
 #if defined(PNG_TIME_RFC1123_SUPPORTED)
-         /* we have to use png_memcpy instead of "=" because the string
+         /* We have to use png_memcpy instead of "=" because the string
             pointed to by png_convert_to_rfc1123() gets free'ed before
             we use it */
          png_memcpy(tIME_string,
@@ -1236,7 +1236,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
          png_size_t i;
          png_set_unknown_chunks(write_ptr, write_end_info_ptr, unknowns,
            num_unknowns);
-         /* copy the locations from the read_info_ptr.  The automatically
+         /* Copy the locations from the read_info_ptr.  The automatically
           * generated locations in write_end_info_ptr are wrong because we
           * haven't written the end_info yet.
           */
@@ -1352,7 +1352,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
    return (0);
 }
 
-/* input and output filenames */
+/* Input and output filenames */
 #ifdef RISCOS
 static PNG_CONST char *inname = "pngtest/png";
 static PNG_CONST char *outname = "pngout/png";
diff --git a/pngtrans.c b/pngtrans.c
index e7c8c2c4a..878e684a1 100644
--- 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 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -25,7 +25,7 @@ png_set_bgr(png_structp png_ptr)
 #endif
 
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
-/* turn on 16 bit byte swapping */
+/* Turn on 16 bit byte swapping */
 void PNGAPI
 png_set_swap(png_structp png_ptr)
 {
@@ -38,7 +38,7 @@ png_set_swap(png_structp png_ptr)
 #endif
 
 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
-/* turn on pixel packing */
+/* Turn on pixel packing */
 void PNGAPI
 png_set_packing(png_structp png_ptr)
 {
@@ -54,7 +54,7 @@ png_set_packing(png_structp png_ptr)
 #endif
 
 #if defined(PNG_READ_PACKSWAP_SUPPORTED)||defined(PNG_WRITE_PACKSWAP_SUPPORTED)
-/* turn on packed pixel swapping */
+/* Turn on packed pixel swapping */
 void PNGAPI
 png_set_packswap(png_structp png_ptr)
 {
@@ -179,7 +179,7 @@ png_set_invert_mono(png_structp png_ptr)
    png_ptr->transformations |= PNG_INVERT_MONO;
 }
 
-/* invert monochrome grayscale data */
+/* Invert monochrome grayscale data */
 void /* PRIVATE */
 png_do_invert(png_row_infop row_info, png_bytep row)
 {
@@ -230,7 +230,7 @@ png_do_invert(png_row_infop row_info, png_bytep row)
 #endif
 
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
-/* swaps byte order on 16 bit depth images */
+/* Swaps byte order on 16 bit depth images */
 void /* PRIVATE */
 png_do_swap(png_row_infop row_info, png_bytep row)
 {
diff --git a/pngwio.c b/pngwio.c
index ae3fbe981..57a9719b8 100644
--- a/pngwio.c
+++ b/pngwio.c
@@ -1,7 +1,7 @@
 
 /* pngwio.c - functions for data output
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -85,7 +85,7 @@ png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
       do
       {
          written = MIN(NEAR_BUF_SIZE, remaining);
-         png_memcpy(buf, data, written); /* copy far buffer to near buffer */
+         png_memcpy(buf, data, written); /* Copy far buffer to near buffer */
          err = fwrite(buf, 1, written, io_ptr);
          if (err != written)
             break;
diff --git a/pngwrite.c b/pngwrite.c
index bec17e05e..59483f801 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,7 +1,7 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -618,7 +618,7 @@ png_write_image(png_structp png_ptr, png_bytepp image)
 
    png_debug(1, "in png_write_image");
 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
-   /* intialize interlace handling.  If image is not interlaced,
+   /* Initialize interlace handling.  If image is not interlaced,
     * this will set pass to 1
     */
    num_pass = png_set_interlace_handling(png_ptr);
diff --git a/pngwtran.c b/pngwtran.c
index d9bf19899..a07b00c48 100644
--- 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 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -26,7 +26,7 @@ png_do_write_transformations(png_structp png_ptr)
 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
       if (png_ptr->write_user_transform_fn != NULL)
-        (*(png_ptr->write_user_transform_fn)) /* user write transform function */
+        (*(png_ptr->write_user_transform_fn)) /* User write transform function */
           (png_ptr,                    /* png_ptr */
            &(png_ptr->row_info),       /* row_info:     */
              /*  png_uint_32 width;          width of row */
@@ -241,7 +241,7 @@ png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
          channels++;
       }
 
-      /* with low row depths, could only be grayscale, so one channel */
+      /* With low row depths, could only be grayscale, so one channel */
       if (row_info->bit_depth < 8)
       {
          png_bytep bp = row;
@@ -426,7 +426,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
             png_uint_32 row_width = row_info->width;
             for (i = 0, sp = dp = row; i < row_width; i++)
             {
-               /* does nothing
+               /* Does nothing
                *(dp++) = *(sp++);
                *(dp++) = *(sp++);
                *(dp++) = *(sp++);
@@ -444,7 +444,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 
             for (i = 0, sp = dp = row; i < row_width; i++)
             {
-               /* does nothing
+               /* Does nothing
                *(dp++) = *(sp++);
                *(dp++) = *(sp++);
                *(dp++) = *(sp++);
@@ -482,7 +482,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 
             for (i = 0, sp = dp = row; i < row_width; i++)
             {
-               /* does nothing
+               /* Does nothing
                *(dp++) = *(sp++);
                *(dp++) = *(sp++);
                */
@@ -497,7 +497,7 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 #endif
 
 #if defined(PNG_MNG_FEATURES_SUPPORTED)
-/* undoes intrapixel differencing  */
+/* Undoes intrapixel differencing  */
 void /* PRIVATE */
 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 {
diff --git a/pngwutil.c b/pngwutil.c
index f47054978..840527ffa 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.4.0 [May 18, 2009]
+ * Last changed in libpng 1.4.0 [May 20, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -63,7 +63,7 @@ png_write_sig(png_structp png_ptr)
    png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 
 #ifdef PNG_IO_STATE_SUPPORTED
-   /* inform the I/O callback that the signature is being written */
+   /* Inform the I/O callback that the signature is being written */
    png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE;
 #endif
 
@@ -185,14 +185,14 @@ png_write_chunk_end(png_structp png_ptr)
 
 typedef struct
 {
-   char *input;   /* the uncompressed input data */
-   int input_len;   /* its length */
-   int num_output_ptr; /* number of output pointers used */
-   int max_output_ptr; /* size of output_ptr */
-   png_charpp output_ptr; /* array of pointers to output */
+   char *input;   /* The uncompressed input data */
+   int input_len;   /* Its length */
+   int num_output_ptr; /* Number of output pointers used */
+   int max_output_ptr; /* Size of output_ptr */
+   png_charpp output_ptr; /* Array of pointers to output */
 } compression_state;
 
-/* compress given text into storage in the png_ptr structure */
+/* Compress given text into storage in the png_ptr structure */
 static int /* PRIVATE */
 png_text_compress(png_structp png_ptr,
         png_charp text, png_size_t text_len, int compression,
@@ -249,11 +249,11 @@ png_text_compress(png_structp png_ptr,
    /* This is the same compression loop as in png_write_row() */
    do
    {
-      /* compress the data */
+      /* Compress the data */
       ret = deflate(&png_ptr->zstream, Z_NO_FLUSH);
       if (ret != Z_OK)
       {
-         /* error */
+         /* Error */
          if (png_ptr->zstream.msg != NULL)
             png_error(png_ptr, png_ptr->zstream.msg);
          else
@@ -370,7 +370,7 @@ png_text_compress(png_structp png_ptr,
    return((int)text_len);
 }
 
-/* ship the compressed text out via chunk writes */
+/* Ship the compressed text out via chunk writes */
 static void /* PRIVATE */
 png_write_compressed_data_out(png_structp png_ptr, compression_state *comp)
 {
@@ -418,7 +418,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
 #endif
    int ret;
 
-   png_byte buf[13]; /* buffer to store the IHDR info */
+   png_byte buf[13]; /* Buffer to store the IHDR info */
 
    png_debug(1, "in png_write_IHDR");
    /* Check that we have valid input data from the application info */
@@ -517,7 +517,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
 
    png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
-   /* set the usr info, so any transformations can modify it */
+   /* Set the usr info, so any transformations can modify it */
    png_ptr->usr_width = png_ptr->width;
    png_ptr->usr_bit_depth = png_ptr->bit_depth;
    png_ptr->usr_channels = png_ptr->channels;
@@ -577,7 +577,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
    png_ptr->zstream.next_out = png_ptr->zbuf;
    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
    /* libpng is not interested in zstream.data_type */
-   /* set it to a predefined value, to avoid its evaluation inside zlib */
+   /* Set it to a predefined value, to avoid its evaluation inside zlib */
    png_ptr->zstream.data_type = Z_BINARY;
 
    png_ptr->mode = PNG_HAVE_IHDR;
@@ -830,7 +830,7 @@ png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
       profile_len = png_text_compress(png_ptr, profile,
         (png_size_t)profile_len, PNG_COMPRESSION_TYPE_BASE, &comp);
 
-   /* make sure we include the NULL after the name and the compression type */
+   /* Make sure we include the NULL after the name and the compression type */
    png_write_chunk_start(png_ptr, (png_bytep)png_iCCP,
           (png_uint_32)(name_len + profile_len + 2));
    new_name[name_len + 1] = 0x00;
@@ -926,7 +926,7 @@ png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
 #endif
 
 #if defined(PNG_WRITE_sBIT_SUPPORTED)
-/* write the sBIT chunk */
+/* Write the sBIT chunk */
 void /* PRIVATE */
 png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
 {
@@ -982,7 +982,7 @@ png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
 #endif
 
 #if defined(PNG_WRITE_cHRM_SUPPORTED)
-/* write the cHRM chunk */
+/* Write the cHRM chunk */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 void /* PRIVATE */
 png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
@@ -1013,7 +1013,7 @@ png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
       int_red_x, int_red_y, int_green_x, int_green_y, int_blue_x, int_blue_y))
 #endif
    {
-      /* each value is saved in 1/100,000ths */
+      /* Each value is saved in 1/100,000ths */
     
       png_save_uint_32(buf, int_white_x);
       png_save_uint_32(buf + 4, int_white_y);
@@ -1044,7 +1044,7 @@ png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
    png_byte buf[32];
 
    png_debug(1, "in png_write_cHRM");
-   /* each value is saved in 1/100,000ths */
+   /* Each value is saved in 1/100,000ths */
 #if !defined(PNG_NO_CHECK_cHRM)
    if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
       green_x, green_y, blue_x, blue_y))
@@ -1087,13 +1087,13 @@ png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
          png_warning(png_ptr, "Invalid number of transparent colors specified");
          return;
       }
-      /* write the chunk out as it is */
+      /* Write the chunk out as it is */
       png_write_chunk(png_ptr, (png_bytep)png_tRNS, trans,
         (png_size_t)num_trans);
    }
    else if (color_type == PNG_COLOR_TYPE_GRAY)
    {
-      /* one 16 bit value */
+      /* One 16 bit value */
       if (tran->gray >= (1 << png_ptr->bit_depth))
       {
          png_warning(png_ptr,
@@ -1105,7 +1105,7 @@ png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
    }
    else if (color_type == PNG_COLOR_TYPE_RGB)
    {
-      /* three 16 bit values */
+      /* Three 16 bit values */
       png_save_uint_16(buf, tran->red);
       png_save_uint_16(buf + 2, tran->green);
       png_save_uint_16(buf + 4, tran->blue);
@@ -1359,7 +1359,7 @@ png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
    else
       text_len = png_strlen(text);
 
-   /* make sure we include the 0 after the key */
+   /* Make sure we include the 0 after the key */
    png_write_chunk_start(png_ptr, (png_bytep)png_tEXt,
       (png_uint_32)(key_len + text_len + 1));
    /*
@@ -1658,8 +1658,8 @@ png_write_sCAL_s(png_structp png_ptr, int unit, png_charp width,
    }
 
    buf[0] = (png_byte)unit;
-   png_memcpy(buf + 1, width, wlen + 1);      /* append the '\0' here */
-   png_memcpy(buf + wlen + 2, height, hlen);  /* do NOT append the '\0' here */
+   png_memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
+   png_memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
 
    png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
    png_write_chunk(png_ptr, (png_bytep)png_sCAL, buf, total_len);
@@ -1769,7 +1769,7 @@ png_write_start_row(png_structp 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))
    {
-     /* set up previous row buffer */
+     /* Set up previous row buffer */
 #ifdef PNG_CALLOC_SUPPORTED
      png_ptr->prev_row = (png_bytep)png_calloc(png_ptr,
         (png_alloc_size_t)buf_size);
@@ -1854,7 +1854,7 @@ png_write_finish_row(png_structp png_ptr)
    int ret;
 
    png_debug(1, "in png_write_finish_row");
-   /* next row */
+   /* Next row */
    png_ptr->row_number++;
 
    /* See if we are done */
@@ -2130,7 +2130,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
 #endif
 
    png_debug(1, "in png_write_find_filter");
-   /* find out how many bytes offset each pixel is */
+   /* Find out how many bytes offset each pixel is */
    bpp = (row_info->pixel_depth + 7) >> 3;
 
    prev_row = png_ptr->prev_row;