ryan/mozjpeg
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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

Browse Source
This commit is contained in:
DRC
2011-02-18 02:41:03 +00:00
parent 72abc29722
commit bb4465f392
1 changed files with 5 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
ChangeLog.txt
View File

@@ -3,13 +3,17 @@
[1] The algorithm used by the SIMD quantization function cannot produce correct [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 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 [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 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. 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 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. 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. [3] Ported jpgtest.cxx to pure C to avoid the need for a C++ compiler.