This Recommendation | International Standard, Digital compression and coding of continuous-tone still images, is published as three parts:

CCITT Rec. T.81 | ISO/IEC 10918-1: Requirements and guidelines;

ITU-T Rec. T.83 | ISO/IEC 10918-2: Compliance testing;

ITU-T Rec. T.84 | ISO/IEC 10918-3: Extensions.

This Recommendation | International Standard sets out requirements and guidelines for encoding and decoding extensions to the processes defined by CCITT Rec. T.81 | ISO/IEC 10918-1, and for the coded representation of compressed image data of these extensions. This Recommendation | International Standard also defines tests for determining whether implementations comply with the requirements for the various encoding and decoding extensions.

This Recommendation | International Standard:

defines extensions [including variable quantization, selective refinement, composite tiling, and a Still Picture Interchange File Format (SPIFF)] to processes for converting source image data to compressed image data;

defines extensions to processes for converting compressed image data to reconstructed image data;

defines coded representations for compressed image data;

gives guidance and examples on how to implement these extensions in practice;

describes compliance tests for these extensions.