ITU-T Rec. T.800 / ISO/IEC 15444-1 defines a set of lossless and lossy compression methods for coding continuoustone, bi-level, greyscale or colour digital still images. This Recommendation / International Standard provides two independently created software reference implementations of ITU-T Rec. T.800 / ISO/IEC 15444-1, in order to assist implementers of ITU-T Rec. T.800 / ISO/IEC 15444-1 in testing and understanding its content.