https://jpeg.org/jpeg2000/
Part 2: Extensions
Part 2 defines codestream and file format extensions including: multi-component transformations; more flexible wavelet tranform kernels and decomposition structures; alternate quantization schemes; and non-linear point transforms. The Part 2 JPX file format extends the Part 1 JP2 file format to allow: more comprehensive color space descriptions and HDR sample representations; multiple codestreams; composition, cropping, geometric transforms; rich animations; descriptive metadata; and a rich metadata set for photographic imagery.
(Opens fine with GIMP.)