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Diffstat (limited to 'src/3rdparty/libjpeg/libjpeg.txt')
| -rw-r--r-- | src/3rdparty/libjpeg/libjpeg.txt | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/src/3rdparty/libjpeg/libjpeg.txt b/src/3rdparty/libjpeg/libjpeg.txt index e5a85c0..2d98e22 100644 --- a/src/3rdparty/libjpeg/libjpeg.txt +++ b/src/3rdparty/libjpeg/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 |