jpeg-9b/libjpeg.txt
A word about functions *not* provided by the library. We handle a subset of
the ISO JPEG standard; most baseline, extended-sequential, and progressive
JPEG processes are supported. (Our subset includes all features now in common
use.) Unsupported ISO options include:
* Hierarchical storage
* Lossless JPEG
* DNL marker
* Nonintegral subsampling ratios
We support 8-bit to 12-bit data precision, but this is a compile-time choice
rather than a run-time choice; hence it is difficult to use different
precisions in a single application.