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66 lines
2.7 KiB
Plaintext
66 lines
2.7 KiB
Plaintext
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Libpng 1.7.0alpha01 - December 15, 2012
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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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Files available for download:
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Source files with LF line endings (for Unix/Linux) and with a
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"configure" script
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1.7.0alpha01.tar.xz (LZMA-compressed, recommended)
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1.7.0alpha01.tar.gz
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1.7.0alpha01.tar.bz2
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Source files with CRLF line endings (for Windows), without the
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"configure" script
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lp170a01.7z (LZMA-compressed, recommended)
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lp170a01.zip
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Other information:
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1.7.0alpha01-README.txt
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1.7.0alpha01-LICENSE.txt
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Changes since the last public release (1.6.0):
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Version 1.7.0alpha01 [December 15, 2012]
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Started 1.7.0 branch from libpng-1.6.0beta33.
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Made 8-bit compose and rgb_to_grayscale accuracy improvements. These
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changes cause 16-bit arithmetic to be used for 8-bit data in the gamma
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corrected compose and grayscale operations. The arithmetic errors have
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three sources all of which are fixed in this commit:
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1) 8-bit linear calculations produce massive errors for lower intensity
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values.
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2) The old 16-bit "16 to 8" gamma table code erroneously wrote the lowest
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output value into a table entry which corresponded to multiple output
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values (so where the value written should have been the closest to the
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transformed input value.)
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3) In a number of cases the code to access the 16-bit table did not round;
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it did a simple shift, which was wrong and made the side effects of (2)
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even worse.
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The new gamma code does not have the 16-to-8 problem at the cost of slighly
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more calculations and the algorithm used to minimize the number of
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calculations has been extended to all the 16-bit tables; it has advantages
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for any significant gamma correction.
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Rearranged png_struct, remove unused members, change png_set_filter handling
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png_struct members rearranged - partly to reorder to avoid packing, partly
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to put frequently accessed members at the start and partly to make
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the grouping more clear. png_set_filter code has been rewritten and the
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code shared with png_write_start_row moved to a common function. Comments
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in png.h have been made more clear. Minor fixes to
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contrib/libtests/timepng.c and some of the png_*_tRNS logic, including
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more error detection in png_set_tRNS.
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Clean up USER_LIMITS feature, removing members from png_struct when not
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required.
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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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https://lists.sourceforge.net/lists/listinfo/png-mng-implement
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to subscribe)
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or to glennrp at users.sourceforge.net
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Glenn R-P
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