[libpng16] Updated documentation about the simplified API.

ANNOUNCE

@@ -174,10 +174,12 @@ Version 1.6.0beta10 [February 3, 2012]
   Added Z_SOLO for zlib-1.2.6+ and correct pngstest tests
   Updated list of test images in CMakeLists.txt
   Updated the prebuilt configure files to current condition.
+  Revised INSTALL information about autogen.sh; it works in tar distributions.
 
 Version 1.6.0beta11 [February 4, 2012]
   Fix character count in pngstest command in projects/owatcom/pngstest.tgt
   Revised test-pngstest.sh to report PASS/FAIL for each image.
+  Updated documentation about the simplified API.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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CHANGES

@@ -3930,6 +3930,7 @@ Version 1.6.0beta10 [February 3, 2012]
 Version 1.6.0beta11 [February 4, 2012]
   Fix character count in pngstest command in projects/owatcom/pngstest.tgt
   Revised test-pngstest.sh to report PASS/FAIL for each image.
+  Updated documentation about the simplified API.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

libpng-manual.txt

@@ -3758,6 +3758,10 @@ READ APIs
       setting the pointer to NULL.  May be called at any time
       after the structure is initialized.
 
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
 
 WRITE APIS
 

png.c

@@ -762,13 +762,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.6.0beta11 - February 3, 2012" PNG_STRING_NEWLINE \
+     "libpng version 1.6.0beta11 - February 4, 2012" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2012 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 1.6.0beta11 - February 3, 2012\
+      return "libpng version 1.6.0beta11 - February 4, 2012\
       Copyright (c) 1998-2012 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -2974,9 +2974,11 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
 #if defined PNG_SIMPLIFIED_READ_SUPPORTED ||\
    defined PNG_SIMPLIFIED_WRITE_SUPPORTED
 /* sRGB conversion tables; these are machine generated with the code in
- * contrib/tools/makesRGB.c.  The sRGB to linear table is exact (to the
- * nearest 16 bit linear fraction).  The inverse (linear to sRGB) table has
- * accuracies as follows:
+ * contrib/tools/makesRGB.c.  The actual sRGB transfer curve defined in the
+ * specification (see the article at http://en.wikipedia.org/wiki/SRGB)
+ * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
+ * The sRGB to linear table is exact (to the nearest 16 bit linear fraction).
+ * The inverse (linear to sRGB) table has accuracies as follows:
  *
  * For all possible (255*65535+1) input values:
  *

png.h

 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.6.0beta11 - February 3, 2012
+ * libpng version 1.6.0beta11 - February 4, 2012
  * Copyright (c) 1998-2012 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 1.6.0beta11 - February 3, 2012: Glenn
+ *   libpng versions 0.97, January 1998, through 1.6.0beta11 - February 4, 2012: Glenn
  *   See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -198,7 +198,7 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.6.0beta11, February 3, 2012, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.6.0beta11, February 4, 2012, are
  * Copyright (c) 2004, 2006-2012 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:
@@ -310,7 +310,7 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    February 3, 2012
+ *    February 4, 2012
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
@@ -376,7 +376,7 @@
 /* Version information for png.h - this should match the version in png.c */
 #define PNG_LIBPNG_VER_STRING "1.6.0beta11"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.6.0beta11 - February 3, 2012\n"
+     " libpng version 1.6.0beta11 - February 4, 2012\n"
 
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -2734,7 +2734,7 @@ typedef struct
  * luminance channels the value is encoded according to the sRGB specification
  * and matches the 8-bit format expected by typical display devices.
  *
- *    The color/gray channels are not scaled (pre-multiplied) by the alpha
+ * The color/gray channels are not scaled (pre-multiplied) by the alpha
  * channel and are suitable for passing to color management software.
  *
  * b) As a value in the range 0..65535, contained in a 2-byte integer.  All
@@ -2743,7 +2743,12 @@ typedef struct
  * the sRGB specification.  This encoding is identified by the
  * PNG_FORMAT_FLAG_LINEAR flag below.
  *
- *    When an alpha channel is present it is expected to denote pixel coverage
+ * When the simplified API needs to convert between sRGB and linear colorspaces,
+ * the actual sRGB transfer curve defined in the sRGB specification (see the
+ * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+ * approximation used elsewhere in libpng.
+ *
+ * When an alpha channel is present it is expected to denote pixel coverage
  * of the color or luminance channels and is returned as an associated alpha
  * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
  * value.