[libpng16] New 'tools' directory containing tools used to generate libpng code.
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6
ANNOUNCE
6
ANNOUNCE
@ -1,5 +1,5 @@
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Libpng 1.6.0alpha01 - November 28, 2011
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Libpng 1.6.0alpha01 - November 29, 2011
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This is not intended to be a public release. It will be replaced
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within a few weeks by a public version or by another test version.
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@ -107,7 +107,7 @@ Version 1.5.7beta05 [(PENDING RELEASE)]
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Added MINGW support to CMakeLists.txt
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Reject invalid compression flag or method when reading the iTXt chunk.
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Version 1.6.0alpha01 [November 28, 2011]
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Version 1.6.0alpha01 [November 29, 2011]
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Removed machine-generated configure files from the GIT repository (they will
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continue to appear in the tarball distributions).
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Restored the new 'simplified' API, which was deleted from libpng-1.5.7.
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@ -130,7 +130,7 @@ Version 1.6.0alpha01 [November 28, 2011]
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image that has a sufficiently large row size (rather than simply failing
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to read such images).
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Replaced an "#if" with "ifdef" in pngrtran.c
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Revised #if PNG_DO_BC blocks in png.c (use #ifdef and add #else)
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New tools directory containing tools used to generate libpng code.
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Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
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(subscription required; visit
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4
CHANGES
4
CHANGES
@ -3752,7 +3752,7 @@ Version 1.5.7beta05 [(PENDING RELEASE)]
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Added MINGW support to CMakeLists.txt
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Reject invalid compression flag or method when reading the iTXt chunk.
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Version 1.6.0alpha01 [November 28, 2011]
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Version 1.6.0alpha01 [November 29, 2011]
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Removed machine-generated configure files from the GIT repository (they will
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continue to appear in the tarball distributions).
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Restored the new 'simplified' API, which was deleted from libpng-1.5.7.
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@ -3775,7 +3775,7 @@ Version 1.6.0alpha01 [November 28, 2011]
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image that has a sufficiently large row size (rather than simply failing
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to read such images).
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Replaced an "#if" with "ifdef" in pngrtran.c
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Revised #if PNG_DO_BC blocks in png.c (use #ifdef and add #else)
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New tools directory containing tools used to generate libpng code.
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Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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(subscription required; visit
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@ -28,7 +28,7 @@
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#include "../../png.h"
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#include "../sRGBtables/sRGB.h"
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#include "../tools/sRGB.h"
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/* The following is to support direct compilation of this file as C++ */
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#ifdef __cplusplus
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26
contrib/tools/README.txt
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26
contrib/tools/README.txt
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This directory (contrib/tools) contains tools used by the authors of libpng.
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Code and data placed in this directory is not required to build libpng,
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however the code in this directory has been used to generate data or code in
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the body of the libpng source. The source code idenftifies where this has
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been done. Code in this directory may not compile on all operating systems
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that libpng supports.
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NO COPYRIGHT RIGHTS ARE CLAIMED TO ANY OF THE FILES IN THIS DIRECTORY.
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To the extent possible under law, the authors have waived all copyright and
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related or neighboring rights to this work. This work is published from:
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United States.
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The files may be used freely in any way.
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The source code and comments in this directory are the original work of the
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people named below. No other person or organization has made contributions to
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the work in this directory.
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ORIGINAL AUTHORS
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The following people have contributed to the code in this directory. None
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of the people below claim any rights with regard to the contents of this
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directory.
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John Bowler <jbowler@acm.org>
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@ -1,14 +1,14 @@
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/*-
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* convert.c
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*
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* Last changed in libpng 1.6.0 [(PENDING RELEASE)]
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*
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* COPYRIGHT: Written by John Cunningham Bowler, 2011.
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* To the extent possible under law, the author has waived all copyright and
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* related or neighboring rights to this work. This work is published from:
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* United States.
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*
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* Convert 8-bit sRGB or 16-bit linear values to another format.
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*
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* Last changed in libpng 1.5.7 [(PENDING RELEASE)]
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* Copyright (c) 2011 Written by John Cunningham Bowler
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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*/
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#define _ISOC99_SOURCE 1
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110
contrib/tools/intgamma.sh
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contrib/tools/intgamma.sh
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#!/bin/sh
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#
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# intgamma.sh
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#
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# Last changed in libpng 1.6.0 [(PENDING RELEASE)]
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#
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# COPYRIGHT: Written by John Cunningham Bowler, 2011.
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# To the extent possible under law, the author has waived all copyright and
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# related or neighboring rights to this work. This work is published from:
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# United States.
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#
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# Shell script to generate png.c 8 and 16 bit log tables (see the code in png.c
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# for details).
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#
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# This script uses the "bc" arbitrary precision calculator to calculate 32 bit
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# fixed point values of logarithms appropriate to finding the log of an 8-bit
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# (0..255) value and a similar table for the exponent calculation.
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#
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# "bc" must be on the path when the script is executed, the math library (-l)
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# must be available
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#
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# function to print out a list of numbers as integers; the function truncates
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# the integers which must be one-per-line
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function print(){
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awk 'BEGIN{
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str = ""
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}
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{
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sub("\\.[0-9]*$", "")
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if ($0 == "")
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$0 = "0"
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if (str == "")
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t = " " $0 "U"
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else
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t = str ", " $0 "U"
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if (length(t) >= 80) {
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print str ","
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str = " " $0 "U"
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} else
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str = t
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}
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END{
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print str
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}'
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}
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#
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# The logarithm table.
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cat <<END
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/* 8-bit log table: png_8bit_l2[128]
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* This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
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* 255, so it's the base 2 logarithm of a normalized 8-bit floating point
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* mantissa. The numbers are 32-bit fractions.
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*/
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static const png_uint_32
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png_8bit_l2[128] =
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{
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END
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#
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bc -lqws <<END | print
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f=65536*65536/l(2)
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for (i=128;i<256;++i) { .5 - l(i/255)*f; }
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END
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echo '};'
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echo
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#
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# The exponent table.
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cat <<END
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/* The 'exp()' case must invert the above, taking a 20-bit fixed point
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* logarithmic value and returning a 16 or 8-bit number as appropriate. In
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* each case only the low 16 bits are relevant - the fraction - since the
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* integer bits (the top 4) simply determine a shift.
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*
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* The worst case is the 16-bit distinction between 65535 and 65534, this
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* requires perhaps spurious accuracty in the decoding of the logarithm to
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* distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
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* of getting this accuracy in practice.
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*
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* To deal with this the following exp() function works out the exponent of the
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* frational part of the logarithm by using an accurate 32-bit value from the
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* top four fractional bits then multiplying in the remaining bits.
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*/
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static const png_uint_32
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png_32bit_exp[16] =
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{
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END
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#
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bc -lqws <<END | print
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f=l(2)/16
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for (i=0;i<16;++i) {
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x = .5 + e(-i*f)*2^32;
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if (x >= 2^32) x = 2^32-1;
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x;
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}
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END
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echo '};'
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echo
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#
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# And the table of adjustment values.
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cat <<END
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/* Adjustment table; provided to explain the numbers in the code below. */
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#if 0
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END
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bc -lqws <<END | awk '{ printf "%5d %s\n", 12-NR, $0 }'
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for (i=11;i>=0;--i){
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(1 - e(-(2^i)/65536*l(2))) * 2^(32-i)
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}
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END
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echo '#endif'
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/* makesRGB.c -- build sRGB-to-linear and linear-to-sRGB conversion tables
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*
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* Last changed in libpng 1.5.7 [(PENDING RELEASE)]
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* Copyright (c) 2011 John Cunningham Bowler
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* Last changed in libpng 1.6.0 [(PENDING RELEASE)]
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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* COPYRIGHT: Written by John Cunningham Bowler, 2011.
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* To the extent possible under law, the author has waived all copyright and
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* related or neighboring rights to this work. This work is published from:
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* United States.
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*
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* Make a table to convert 8-bit sRGB encoding values into the closest 16-bit
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* linear value.
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/*-
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* sRGB.h
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*
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* Last changed in libpng 1.5.7 [(PENDING RELEASE)]
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* Copyright (c) 2011 John Cunningham Bowler
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* Last changed in libpng 1.6.0 [(PENDING RELEASE)]
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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* COPYRIGHT: Written by John Cunningham Bowler, 2011.
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* To the extent possible under law, the author has waived all copyright and
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* related or neighboring rights to this work. This work is published from:
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* United States.
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*
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* Utility file; not actually a header, this contains definitions of sRGB
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* calculation functions for inclusion in those test programs that need them.
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