This Recommendation defines a format for digital compression and coding of still images supporting the use of an alternative arithmetic coder called the "Q15-coder" and an alternative baseline compared to ITU-T Rec. T.81 | ISO/IEC 10918-1 (JPEG-1). Support of the Huffman entropy coding method specified in ITU-T Rec. T.81 (JPEG-1) is not required in this Recommendation.

The Q15-coder resolves the carry in the decoder instead of in the encoder, and so has a low latency compared to the QM-coder arithmetic coder incorporated in T.81, which has a potential latency of the rest of the entire entropy-coded segment.

This Recommendation also specifies a DCT with input precision of 16 bits, which is greater than the precision of the T.81 (JPEG-1) DCT.