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git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.1.x@379 632fc199-4ca6-4c93-a231-07263d6284db

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2011-02-18 02:41:03 +00:00
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ChangeLog.txt
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@@ -3,13 +3,17 @@
[1] The algorithm used by the SIMD quantization function cannot produce correct
results when the JPEG quality is >= 98 and the fast integer forward DCT is
used. Thus, the non-SIMD quantization function is now used for those cases.
used. Thus, the non-SIMD quantization function is now used for those cases,
and libjpeg-turbo should now produce identical output to libjpeg v6b in all
cases.
[2] Despite the above, the fast integer forward DCT still degrades somewhat for
JPEG qualities greater than 95, so TurboJPEG/OSS will now automatically use the
slow integer forward DCT when generating JPEG images of quality 96 or greater.
This reduces compression performance by as much as 15% for these high-quality
images but is necessary to ensure that the images are perceptually lossless.
It also ensures that the library can avoid the performance pitfall created by
[1].
[3] Ported jpgtest.cxx to pure C to avoid the need for a C++ compiler.