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| author | Michael R Sweet <michael.r.sweet@gmail.com> | 2011-02-15 15:28:27 +0000 |
|---|---|---|
| committer | Michael R Sweet <michael.r.sweet@gmail.com> | 2011-02-15 15:28:27 +0000 |
| commit | f8697125f4ac2e0690ee0e5be408ff35be29252e (patch) | |
| tree | 67d8dc37339502ef09c92971b940f35fa82ce5b0 /jpeg/libjpeg.txt | |
| parent | 1216e9530fe541df6b95ffa39d00df9919cee4fa (diff) | |
Merge changes from JPEG 8c (released Jan 16, 2011)
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@8426 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
Diffstat (limited to 'jpeg/libjpeg.txt')
| -rw-r--r-- | jpeg/libjpeg.txt | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/jpeg/libjpeg.txt b/jpeg/libjpeg.txt index e5a85c0e3..2d98e22fc 100644 --- a/jpeg/libjpeg.txt +++ b/jpeg/libjpeg.txt @@ -1,6 +1,6 @@ USING THE IJG JPEG LIBRARY -Copyright (C) 1994-2009, Thomas G. Lane, Guido Vollbeding. +Copyright (C) 1994-2010, Thomas G. Lane, Guido Vollbeding. This file is part of the Independent JPEG Group's software. For conditions of distribution and use, see the accompanying README file. @@ -876,6 +876,18 @@ jpeg_simple_progression (j_compress_ptr cinfo) Compression parameters (cinfo fields) include: +int block_size + Set DCT block size. All N from 1 to 16 are possible. + Default is 8 (baseline format). + Larger values produce higher compression, + smaller values produce higher quality. + An exact DCT stage is possible with 1 or 2. + With the default quality of 75 and default Luminance qtable + the DCT+Quantization stage is lossless for value 1. + Note that values other than 8 require a SmartScale capable decoder, + introduced with IJG JPEG 8. Setting the block_size parameter for + compression works with version 8c and later. + J_DCT_METHOD dct_method Selects the algorithm used for the DCT step. Choices are: JDCT_ISLOW: slow but accurate integer algorithm @@ -895,8 +907,10 @@ J_DCT_METHOD dct_method unsigned int scale_num, scale_denom Scale the image by the fraction scale_num/scale_denom. Default is 1/1, or no scaling. Currently, the supported scaling ratios are - 8/N with all N from 1 to 16. (The library design allows for arbitrary - scaling ratios but this is not likely to be implemented any time soon.) + M/N with all N from 1 to 16, where M is the destination DCT size, + which is 8 by default (see block_size parameter above). + (The library design allows for arbitrary scaling ratios but this + is not likely to be implemented any time soon.) J_COLOR_SPACE jpeg_color_space int num_components |