[devel] Imported from libpng-1.5.0beta17.tar
diff --git a/libpng.3 b/libpng.3
index 36cf625..c3a5a8a 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,4 +1,4 @@
-.TH LIBPNG 3 "April 14, 2010"
+.TH LIBPNG 3 "April 17, 2010"
.SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta17
.SH SYNOPSIS
@@ -458,10 +458,6 @@
\fI\fB
-\fBvoid png_set_dither (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_dither\fP\fB);\fP
-
-\fI\fB
-
\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
\fI\fB
@@ -586,6 +582,10 @@
\fI\fB
+\fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP
+
+\fI\fB
+
\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
\fI\fB
@@ -789,7 +789,7 @@
.SH LIBPNG.TXT
libpng.txt - A description on how to use and modify libpng
- libpng version 1.5.0beta17 - April 14, 2010
+ libpng version 1.5.0beta17 - April 17, 2010
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2009 Glenn Randers-Pehrson
@@ -800,7 +800,7 @@
Based on:
- libpng versions 0.97, January 1998, through 1.5.0beta17 - April 14, 2010
+ libpng versions 0.97, January 1998, through 1.5.0beta17 - April 17, 2010
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2009 Glenn Randers-Pehrson
@@ -1268,7 +1268,7 @@
to RGB (or GA to RGBA)
(This excludes setting a background color, doing gamma transformation,
-dithering, and setting filler.) If this is the case, simply do this:
+quantizing, and setting filler.) If this is the case, simply do this:
png_read_png(png_ptr, info_ptr, png_transforms, NULL)
@@ -1955,6 +1955,40 @@
else
png_set_gamma(png_ptr, screen_gamma, 0.45455);
+If you need to reduce an RGB file to a paletted file, or if a paletted
+file has more entries then will fit on your screen, png_set_quantize()
+will do that. Note that this is a simple match dither that merely
+finds the closest color available. This should work fairly well with
+optimized palettes, and fairly badly with linear color cubes. If you
+pass a palette that is larger then maximum_colors, the file will
+reduce the number of colors in the palette so it will fit into
+maximum_colors. If there is a histogram, it will use it to make
+more intelligent choices when reducing the palette. If there is no
+histogram, it may not do as good a job.
+
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ if (png_get_valid(png_ptr, info_ptr,
+ PNG_INFO_PLTE))
+ {
+ png_uint_16p histogram = NULL;
+
+ png_get_hIST(png_ptr, info_ptr,
+ &histogram);
+ png_set_quantize(png_ptr, palette, num_palette,
+ max_screen_colors, histogram, 1);
+ }
+ else
+ {
+ png_color std_color_cube[MAX_SCREEN_COLORS] =
+ { ... colors ... };
+
+ png_set_quantize(png_ptr, std_color_cube,
+ MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
+ NULL,0);
+ }
+ }
+
PNG files describe monochrome as black being zero and white being one.
The following code will reverse this (make black be one and white be
zero):
@@ -3907,10 +3941,14 @@
The png_zalloc() function no longer zeroes out the memory that it
allocates.
-Support for dithering was removed by default, because it has never
-been well tested and doesn't work very well. The code has not
-been removed, however, and can be enabled by building libpng with
-PNG_READ_DITHER_SUPPORTED defined.
+Support for dithering was disabled by default in libpng-1.4.0, because
+been well tested and doesn't actually "dither". The code was not
+removed, however, and could be enabled by building libpng with
+PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
+was reenabled, but the function was renamed png_set_quantize() to
+reflect more accurately what it actually does. At the same time,
+the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
+PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS.
We removed the trailing '.' from the warning and error messages.
@@ -4052,7 +4090,7 @@
.SH XIII. Y2K Compliance in libpng
-April 14, 2010
+April 17, 2010
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
@@ -4292,7 +4330,7 @@
Thanks to Frank J. T. Wojcik for helping with the documentation.
-Libpng version 1.5.0beta17 - April 14, 2010:
+Libpng version 1.5.0beta17 - April 17, 2010:
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
@@ -4315,7 +4353,7 @@
This code is released under the libpng license.
-libpng versions 1.2.6, August 15, 2004, through 1.5.0beta17, April 14, 2010, are
+libpng versions 1.2.6, August 15, 2004, through 1.5.0beta17, April 17, 2010, 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
@@ -4414,7 +4452,7 @@
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
-April 14, 2010
+April 17, 2010
.\" end of man page
