10.19 Transfer Syntax For Lossless and Lossy JPEG XL Compression
One Transfer Syntax is specified for JPEG XL Lossless Image Compression, one for JPEG XL JPEG Recompression, which allows for transcoding JPEG encoded data without additional loss, and one for a general JPEG XL Image Compression scheme for any JPEG XL encoded data.
Any of these may be negotiated separately and there is no default or baseline specified (other than as described in Section 10.1).
Note
When a JPEG Baseline encoded image is transcoded to JPEG XL, if the JPEG XL JPEG Recompression Transfer Syntax is used rather than the JPEG XL Transfer Syntax, then it communicates that the exact bitwise representation of JPEG can be recovered.