Comment by CharlesW
JXL's war is not with AVIF, which is already a de-facto standard which has near-universal browser support, is enshrined as an Apple image default, will only become more popular as AV1 video does, etc. It's not going anywhere.
That's not to say that JXL is bad or going away. It currently has poor browser support, but it's now finding its footing in niche use cases (archival, prosumer photography, medical), and will eventually become ubiquitous enough to just be what the average person refers to as "JPEG" 10 years from now.
To address selected claims made in the post:
• "AVIF is 'homegrown'" – AVIF is an open, royalty-free AOMedia standard developed by the Alliance for Open Media (Google, Microsoft, Amazon, Netflix, Mozilla, etc.).
• "AVIF is 'inferior'" – AVIF is significantly better than JPEG/WebP in compression efficiency at comparable quality, and comparable with JXL in many scenarios.
• "AVIF is ridiculous in this aspect, capping at 8,193×4,320." — JXL's theoretical maximum image size is bigger. The author cites AVIF's Baseline profile (think embedded devices), but AVIF supports 16,384×8,704 per tile. It HEIF container format supports a grid of up to 65,535 tiles (so logical images sizes up to 1,073,725,440 wide or 283,111,200 tall).
So, JPEG XL is good. Yes, it's far behind AVIF in terms of adoption and ecosystem, but that will improve. AVIF is likely to erase any current JXL quality advantages with AV2, but both JXL and AV1/AV2 encoders will get better with time, so they're likely to be neck-and-neck in quality for the foreseeable future.
Yes AVIF is better at compressing than jpeg and even webp, that should be taken for granted given its a newer format. But no its not remotely competitive with JXL, the only benchmarks it trades blows are ones with laughably low quality settings beyond what any user would ever use. Real world usage paints a very different picture.
JXL not only has better compression rates at equivalent qualities for sane settings, it does so with faster encoding and decoding, while also supporting progressive decoding leveraging image saliency.
AV2 might bring it closer on par with JXL in compression but to suggest they're at all equal is a joke.