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[devel] Fix and clarify LEGACY 16-to-8 scaling.

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John Bowler
2011-06-13 20:50:42 -05:00
committed by Glenn Randers-Pehrson
parent 97039baa88
commit 74945f2f04
2 changed files with 7 additions and 7 deletions
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10
pngrtran.c
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@@ -1,7 +1,7 @@
/* pngrtran.c - transforms the data in a row for PNG readers
*
* Last changed in libpng 1.5.3 [(PENDING RELEASE)]
* Last changed in libpng 1.5.4 [(PENDING RELEASE)]
* Copyright (c) 1998-2011 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.)
@@ -2499,17 +2499,17 @@ png_do_chop(png_row_infop row_info, png_bytep row)
* (V * 255 + 32895) >> 16
*/
#ifdef PNG_LEGACY_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
*dp = *sp + ((((int)(*(sp + 1)) - *sp) > 128) ? 1 : 0);
#else
png_int_32 tmp = *sp++; /* must be signed! */
#ifdef PNG_LEGACY_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
tmp += (((int)*sp++ - tmp) > 128) ? 1 : 0;
#else
# ifdef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
# else
sp++;
# endif
*dp++ = (png_byte)tmp;
#endif
*dp++ = (png_byte)tmp;
}
row_info->bit_depth = 8;