diff options
Diffstat (limited to 'libjpeg.txt')
| -rw-r--r-- | libjpeg.txt | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/libjpeg.txt b/libjpeg.txt index afc002b..5f203d6 100644 --- a/libjpeg.txt +++ b/libjpeg.txt @@ -897,12 +897,14 @@ J_DCT_METHOD dct_method JDCT_ISLOW, but this can be larger for some images. Do not use JDCT_IFAST with quality levels above 97. The algorithm often degenerates at quality=98 and above and can actually produce a more - lossy image than if lower quality levels had been used. JDCT_FLOAT is - mostly a legacy feature. It does not produce significantly more - accurate results than the ISLOW method, and it is much slower. The - FLOAT method may also give different results on different machines due - to varying roundoff behavior, whereas the integer methods should give - the same results on all machines. + lossy image than if lower quality levels had been used. Also, in + libjpeg-turbo, JDCT_IFAST is not fully accelerated for quality levels + above 97, so it will be slower than JDCT_ISLOW. JDCT_FLOAT is mainly a + legacy feature. It does not produce significantly more accurate + results than the ISLOW method, and it is much slower. The FLOAT method + may also give different results on different machines due to varying + roundoff behavior, whereas the integer methods should give the same + results on all machines. J_COLOR_SPACE jpeg_color_space int num_components @@ -1199,7 +1201,7 @@ J_DCT_METHOD dct_method when decompressing images that were compressed using quality levels above 97. The algorithm often degenerates for such images and can actually produce a more lossy output image than if the JPEG image had - been compressed using lower quality levels. JDCT_FLOAT is mostly a + been compressed using lower quality levels. JDCT_FLOAT is mainly a legacy feature. It does not produce significantly more accurate results than the ISLOW method, and it is much slower. The FLOAT method may also give different results on different machines due to varying |