Jon Sneyers

Repeated recompression does occur in practice. Memes typically get shared in lossy formats, and can get recompressed dozens of times because: - the image goes from one social media platform...

SSIMULACRA2, just like DSSIM, is based on MS-SSIM. When implementing MS-SSIM, there are some choices to be made, such as: - What colorspace to apply it to? Luma only or...

I assume this issue is caused by this: https://github.com/libjxl/libjxl/commit/27afa5e4c2e66d917746f407674369f19b6fca47

This is why independent decoders are so nice to have. This has been a libjxl bug that went undetected because both encoder and decoder have the same bug so images...

My position is to treat it as a bug-that-becomes-spec. Trying both variants in the encoder does not result in significant differences in compression. On some images, the libjxl way is...

The question is what to do when the tag doesn't match the profile. In this case the tag describes the actual color space while the profile implements some kind of...

Technically, if the profile is wrong, lcms can do anything and still be a conforming implementation of the ICC spec :) The ICC spec doesn't say what should take precedence...

The CICP tag basically just describes primaries and a transfer function, which is something lcms can already handle just fine, no?

The only things that are used in practice right now, as far as I can tell, are three sets of primaries (sRGB, P3 and Rec2020) and three transfer curves (sRGB,...

In the example I have, the primaries in the main part of the profile are identical to the ones signaled in the CICP tag of the profile, but yes, it...