[devel] Make the 16-to-8 scaling accurate. Dividing by 256 with no rounding is

wrong (high by one) 25% of the time. Dividing by 257 with rounding is
    wrong in 128 out of 65536 cases. Getting the right answer all the time
    without division is easy.
This commit is contained in:
John Bowler
2011-06-10 23:24:58 -05:00
committed by Glenn Randers-Pehrson
parent cc2770850a
commit b2bee3374c
12 changed files with 81 additions and 55 deletions

View File

@@ -915,7 +915,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
# endif
#endif
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
/* Normally one would use Z_DEFAULT_STRATEGY for text compression.
* This is here just to make pngtest replicate the results from libpng
* versions prior to 1.5.3, and to test this new API.