ITU-T Recommendations

Recommendation ITU-T T.801 | ISO/IEC 15444-2 defines a set of lossless (bit-preserving) and lossy compression methods for coding continuous-tone, bi-level, grey-scale, colour digital still images, or multi-component images.
This Recommendation | International Standard:
– specifies extended decoding processes for converting compressed image data to reconstructed image data;
– specifies an extended codestream syntax containing information for interpreting the compressed image data;
– specifies an extended file format;
– specifies a container to store image metadata;
– defines a standard set of image metadata;
– provides guidance on extended encoding processes for converting source image data to compressed image data;
– provides guidance on how to implement these processes in practice.
Since the first edition of this Recommendation | International Standard in 2004, it has been supplemented by amendments and corrigenda, several of its normative references have been obsoleted, and industry practices have evolved. This second edition addresses these shortcomings without modifying its scope, and includes the following main changes:
– Annex N ("JPX file format extended metadata definition and syntax") is deprecated;
– the Registration Authority specified in M.7, which was never created or used, is cancelled;
– signalling for HTJ2K codestreams, as specified in Rec. ITU-T T.814 | ISO/IEC 15444-15, is added;
– the RLT marker segment is added;
– references have been revised to their currently in-force editions;
– signalling for codestreams that conform to ISO/IEC 21122-1 is added;
– parameterized colourspace is added to the Colour Specification box;
– outstanding amendments and corrigenda are consolidated; and
– the definition of the CAP marker segment was moved to Rec. ITU-T T.800 (2019) | ISO/IEC 15444-1:2019.
This second edition cancels and replaces the first edition (ITU-T T.801 (2002) | ISO/IEC 15444-2:2004), which has been technically revised. It also incorporates the following amendments and corrigenda: ITU-T T.801 (2002) Amd.2 (2005) | ISO/IEC 15444-2:2004/Amd.2:2006, ITU-T T.801 (2002) Amd.3 (2013) | ISO/IEC 15444-2:2004/Amd.3:2015, ITU T T.801 (2002) Amd.4 (2012) | ISO/IEC 15444-2:2004/Amd.4:2015; ITU-T T.801 (2002) Cor.3 (2005) | ISO/IEC 15444-2:2004/Cor.3:2005 and ITU-T T.801 (2002) Cor.4 (2006) | ISO/IEC 15444-2:2004/Cor.4:2007.