Manish Singh <yosh <at> gimp.org> writes:
> On Tue, Feb 08, 2005 at 08:19:29PM +0200, Antti MÃkelÃ wrote:
> > (No lectures on the default 85 being "enough", thank you - it is not
> > enough, and I can clearly see artifacts on my edited digital photographs if
> > saved with 85.).
> You do get the lecture from the libjpeg documentation:
> Quality values above about 95 are NOT recommended for normal use;
> the compressed file size goes up dramatically for hardly any gain
> in output image quality.
Who said Mr. MÃkelÃ would be happy with "normal use"?
When you look at the pixel level, there is a definitive difference between
quality values 95 and 98. This is particularly true in places with strong
gradients. Even Q value 95 may from time to time mush colours.
JPEG compression Q value 98 was chosen by us as the default compression quality
because with that value cjpeg creates pictures that are approximately the same
size as the original JPEG "camera negatives" that you get from the Canon
PowerShot G1 - G5 when using highest JPEG quality. That is, with G3, both
originals and edited 4 Mpix images are roughly 2 MiB. Also, as opposed to
quality value 95, we couldn't detect any JPEG artifacts apart from the
chroma degradation caused by JPEG's default 4:2:0 subsampling.
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