In addition to the compression, JPEG-XL has some nice features that make it better image format. It also does lossless compression. It does color spaces.
One cool feature is that can losslessly convert JPEG into JPEG-XL. And back to JPEG. I can't tell if this applies to all or only converted ones, but it might make good source format and convert to JPEG on export.
> I can't tell if this applies to all or only converted ones
JPEG-XL to JPEG is only lossless for JPEG-XL images which were upgraded from JPEG.
Not all JPEG-XL images can even be represented as JPEG; in particular, images with more than three channels (like images with transparency, or images with CMYK color) or with multiple frames (like an animation) certainly can't.
What about those that can be represented? Is it possible to convert lpsslessly by losing some compression efficiency or still only upgraded can be downgraded?
JPEG XL has many compression modes inside, and the lossless JPEG roundtrip works only for one of them that was specifically designed to hold old JPEG's data. You can't take an arbitrary JXL file and turn it into a JPEG without lossy recompression.
The old-JPEG-preserving compression mode also isn't the best that JXL can do. It's better than the old JPEG, but not as good as JXL using all the new bells and whistles.
For images at low bit per pixel, HEIC is actually quite a bit better than JPEG-XL current encoder. I wouldn't say really an upgrade technically speaking, I would put them on same level with XL have some additional interesting feature.
But considering getting HEIC included in other system seems to be difficult due to patents or other reasons. JPEG-XL seems to be the best middle ground in everything.
I am still hoping there could be additional work on JXL in terms of low bit per pixel improvement and encoding / decoding resource usage. Especially in the lossless front.
Yes, the progressive rendering is really cool, lossless mode is better, lossless recompression of JPEGs is a cool feature, it's faster, it supports larger images (without tiling) with more channels and higher bit depths.
Compared to the stark differences between BMP/JPG/PNG/GIF, there's a ton of overlap between WEBP/HEIC/AVIF/JPEGXL.
Naturally, some types of images tend to compress better with some formats than others, and then you may have to take into account things like the desired quality level, encoding time, etc.
Realistically, any of those four new formats would be fine for 99% of the images that exist, but it would still be nice for every browser to support them all so that web developers can choose their favorite format.
Although, on the flip side, the drawback of having so many formats floating around is that software developers have to spend more time supporting it all. Even trillion dollar companies like Microsoft are seemingly in no rush to make sure that formats like WebP are as well integrated into their software as JPG/PNG were.
You forgot that that 12.5% could change "overnight" if Google change their hostile stance, and adding it as a default in a very popular phone increases the chances of that happening, so add a few zeroes to that 2
One cool feature is that can losslessly convert JPEG into JPEG-XL. And back to JPEG. I can't tell if this applies to all or only converted ones, but it might make good source format and convert to JPEG on export.