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.
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.
If you’re really saving 20% in file size with XL, adding back a very compressed preview image that takes up one or two percent isn’t going to cost you much.
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:
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.
Would completely defeat the purpose of making a new smaller file format if we prefix if with the old format.
That would have been a brilliant move with wav vs MP3
If you’re really saving 20% in file size with XL, adding back a very compressed preview image that takes up one or two percent isn’t going to cost you much.