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Both of these projects have chroma upsampling.
by ache7 6y ago
Both of these projects have chroma upsampling.
- astrange 6y agoAll JPEG decoders have chroma upsampling. Here jpeg2png only seems to actually optimize it though; seems like it works but optimizing for "smoothness" could maybe be improved. I'm suggesting something like eedi3 (http://avisynth.nl/index.php/Eedi3 http://avisynth.nl/index.php/Eedi3) but guided by the luma plane. Oh, you can also jointly optimize the YUV-RGB conversion because if the pixel ends up out of range in RGB space it is probably a compression artifact. I read a paper on this once but haven't seen it implemented.
- ache7 6y ago"All JPEG decoders have chroma upsampling." Well, I meant better upsampling than bilinear interpolation, which blurs chroma. "Oh, you can also jointly optimize the YUV-RGB conversion because if the pixel ends up out of range in RGB space it is probably a compression artifact." Probably not, I suspect that the mozjpeg encoder may use this, so images with black on white text look better (artifact noise go beyond of range).