The case against JPEG XL
Points and comments are a snapshot, not live.
JPEG XL is a technically impressive codec but adds little to the Web platform over AVIF.
The author, an image compression engineer, argues JPEG XL is not needed on the Web. Lossy compression is dominant for most Web uses, and AVIF now matches or outperforms JPEG XL on perceptual quality and metrics like CVVDP and SSIMULACRA2. Lossless JPEG XL offers only ~11.9% savings over lossless WebP on an unrealistic dataset. Decode time for JPEG XL is poor: WebP decodes over 10x faster. JPEG XL's features like progressive decode and JPEG recompression come with downsides or are matched by AVIF. The format's complex coding tools (no directional prediction, limited deblocking, awkward patch system) make it harder to optimize. The author concludes JPEG XL can thrive outside the Web in professional and scientific imaging but is not a strong fit for browsers.
What commenters are saying
The author fields questions in the comments. Commenters push back on the dismissal of lossless Web images, noting art communities and screen capture use cases need lossless. One commenter argues that browser support is critical for JPEG XL adoption in cameras and consumer photo storage, citing HDR and lossless JPEG recompression as compelling. Another flags that Firefox and Chrome have committed to shipping JPEG XL later this year. A nitpick requests clearer graph labeling for lay readers.