How would a new format be backwards-compatible? At least JPEG-XL can losslessly compress standard jpg for a bit of space savings, and servers can choose to deliver the decompressed jpg to clients that don't support JPEG-XL.

Also from Wikipedia:

Computationally efficient encoding and decoding without requiring specialized hardware: JPEG XL is about as fast to encode and decode as old JPEG using libjpeg-turbo

Being a JPEG superset, JXL provides efficient lossless recompression options for images in the traditional/legacy JPEG format that can represent JPEG data in a more space-efficient way (~20% size reduction due to the better entropy coder) and can easily be reversed, e.g. on the fly. Wrapped inside a JPEG XL file/stream, it can be combined with additional elements, e.g. an alpha channel.

[+] reddig33@lemmy.world -25 points 1 day ago (1 children)

All you have to do is add a small traditional JPEG image at the start of the file. It doesn’t have to be high resolution or more than a couple of kb. The new format decoder would know this, and skip the traditional jpeg “header”, rendering the newer file format embedded in the image.

[–] wischi@programming.dev 47 points 1 day ago (2 children)

Would completely defeat the purpose of making a new smaller file format if we prefix if with the old format.

[–] Laser@feddit.org 14 points 1 day ago

That would have been a brilliant move with wav vs MP3