I don't think Google changed their position. It seems it's just a PR made by a random person. Their account was created two days ago and they have no other contributions.
What's JPEG XL? Everyone knows about boring old JPEG, there was also a JPEG 2000 standard that nobody used in practice because it was said to be patent encumbered. Is JPEG XL related to that?
TLDR is JPEG XL is a new standard (not related to JPEG 2000) that among other things allows lossless re-compression of JPEG images with roughly 30% space savings, as well as a bunch of other useful features (better progressive decompression, bigger blocks, reduced banding, higher bit-depth, etc.
It hasn't even been added back because it wasn't removed. This diff just shows the removal of a piece of text announcing it will be removed in the future. There's nothing to discuss here.
This is the umpteenth post on the subject in weeks. Why is this such a big deal? Who uses JPEG XL? I don't think I've ever seen a JPEG XL image in my life.
It's the next gen image format. I believe it's the only way to view HDR images. Adobe, Facebook et al all want to see it in browsers. And I converted all my family photos to it, to save a lot of space at a very high quality.
Its not a next gen image format, though. Using single frame H264/H265/AV1 MP4s is the next gen image format that is already being used. This is what HEIF is (HEIC is H265 in HEIF, AVIF is AV1 in HEIF, AVCI is H264 in HEIF, etc). I can already do HDR with these, and several phone camera apps (such as Apple's stock one) can save an HDR photo as HDR in that format.
video based image formats have a ton of downsides. Modern video codecs are all designed for large resolutions, while things like icons are often pretty small (64x64 or less). Videos don't support transparency, don't care about progressive scans, and are more lenient for certain types of errors because people don't spend time looking at every frame. As such, there are a lot of reasons why it is beneficial to use an image first format. https://cloudinary.com/blog/how_jpeg_xl_compares_to_other_im... has some comparisons showing how much better JPEG-XL is than HEIC/webp.
JPEG XL is about one image codec generation ahead of HEIF and AVIF in my own experiments and personal evaluations. Butteraugli, an objective metric I developed originally for guetzli, during 2014 to 2022, also agrees with this evaluation, as well as the large-scale human rater study by cloudinary.
Many objective metrics get really confused about JPEG XL as it uses some pretty advanced psychovisual modeling that is not implemented in usual metrics.
The best metrics to try in my opinion are butteraugli, ssimulacra 2 and -- with some reservations -- dssim.
At the kind of high quality settings many still images are encoded at, jpeg XL often beats all those other formats in quality/bit (at _low_ bitrates the video-derived formats win). Furthermore, in lossless mode it does significantly better than png; many of the formats you list either don't have a lossless mode, or aren't at all competitive in lossless mode. It also supports bitwise-identical jpeg recompression (which naturally isn't quite as efficient as from-scratch compression as jpegXL), making for a very, very easy transition story that immediately provides significant savings, while also having a seemless path to use native jxl images in the future. It supports per-pixel alpha and animation. It allows for very high bit depths and images sizes, making it convenient in authoring workflows too. Another authoring feature that matters is generation loss - decoding and recompressing repeatedly causes much less distortion in the reference jxl encoder than typically seen in heif, avif or webp. And it's also computationally much, much cheaper - HEIF and particularly AVIF can be quite expensive to encode. Unlike HEIF, there don't seem to be patent issues yet.
In essence: it's best or near-best at almost all workloads, all in one, while being more practical to use to boot. It's just the still image codec you _want_ to be using, instead of having to fiddle with the various tradeoffs the others have.
Need to support non-modern clients or have lots of existing jpegs? jxl allows jpeg recompression with cheap and exact jxl->jpeg reconstruction.
Have tons and tons of images that aren't necessarily going to be viewed often; or have dynamic image generation? Compression is much faster than other competing modern formats; decoding speed
Have some pixel art or geometric diagrams? Jxl does better here than png, and better than all other competing formats (excluding a few very niche hyper-slow research formats).
Just don't want to worry too much about your exact workload? Jxl does well at pretty much everything.
Have users that have the bad habit of opening, editing, and resaving lossy images? Jxl introduces less generation loss.
Have huge images, but don't want to wait for the whole thing to load? Jxl supports progressive decoding.
Have various layers or other editing-workflow-related (meta)data? Jxl supports that, while also having best-in-class compression rates at high or lossless quality, and also having fast encode and decode times
JpegXL is probably the best format to use for almost every image you encounter. That's why it's a shame to see chrome dragging its feet here.
