It's not just Google, Mozilla has no desire to introduce a barely supported massive C++ decoder for marginal gains either:

https://github.com/mozilla/standards-positions/pull/1064

avif is just better for typical web image quality, it produces better looking images and its artifacts aren't as annoying (smoothing instead of blocking and ringing around sharp edges).

You also get it for basically free because it's just an av1 key frame. Every browser needs an av1 decoder already unless it's willing to forego users who would like to be able to watch Netflix and YouTube.

Wanted to note https://issues.chromium.org/issues/40141863 on making the lossless JPEG recompression a Content-Encoding, which provides a way that, say, a CDN could deploy it in a way that's fully transparent to end users (if the user clicks Save it would save a .jpg).

(And: this is great! I think JPEG XL has chance of being adopted with the recompression "bridge" and fast decoding options, and things like progressive decoding for its VarDCT mode are practical advantages too.)

> and generally its HDR support is much better than AVIF

Not anymore. JPEG had the best HDR support with ISO 21496-1 weirdly enough, but AVIF also just recently got that capability with 1.2 ( https://aomedia.org/blog%20posts/Libavif-Improves-Support-fo... ).

The last discussion in libjxl about this was seemingly taking the stance it wasn't necessary since JXL has "native HDR" which completely fails to understand the problem space entirely.

> (in Rust?)

Looks like that's the idea: https://issues.chromium.org/issues/462919304

Ah, I think I searched for "jpegxl", that's why there was no match.

If I remember correctly, WebP was single-handedly forced into adoption by Chrome, while offering only marginal improvements over existing formats. Mozilla even worked on an improved JPEG encoder, MozJPEG, to show it could compete with WebP very well. Then came HEIF and AVIF, which, like WebP, were just repurposed video codecs.

JPEG XL is the first image format in a long while that's been actually designed for images and brings a substantial improvement to quality while also covering a wide range of uses and preserving features that video codecs don't have. It supports progressive decoding, seamless very large image sizes, potentially large amount of channels, is reasonably resilient against generation loss, and more. The fact that it has no major drawbacks alone gives it much more merit than WebP has ever had. Lossless recompression is in addition to all of that.

The difference is that this time around, Google has single-handedly held back the adoption of JPEG XL, while a number of other parties have expressed interest.