Аннотация:Lossless image compression has often employed techniques quite separate from those used for text compression or lossy image compression; most standards today employ modelling followed by coding (e.g. the JBIG standard, the IBM Q-coder, CCITT Group 4). Constantinescu and Storer present a lossy image compression scheme that can be viewed as a generalization of lossless dynamic dictionary compression ('LZ2'-type methods) to two dimensions with approximate matching; recently, Constantinescu and Storer have experimented with this approach for lossless bi-level image compression with great success. Here we generalize 'LZ1'-type methods (that identify matches in previously seen text) to lossless image compression. We examine complexity issues and finish by considering practical 2-D implementations for bi-level images.
