alt Hacker News> Jpeg-XL's key win was only lossless translation of existing jpeg to a modern format.
Huh?
JpegXL is the only widely supported format (once it comes to the various browser as is planned) that can store true HDR linear images in floating point (fp16 and fp32) formats.
AVIF can only do 10 bit integer ranges, sure that HDR compared to 8bit but it is not sufficient for useful extended range color spaces.
The format is widely supported, but I'd be very surprised if linear HDR becomes widely supported outside of image editors. JPEG-XR supported fp32 linear HDR way earlier anyway, and no one cared because no one cares about linear HDR after editing.
Also AVIF supports up to 12 bits.