An improved fractal coding procedure for greyscale images

A refined version of the fractal image coding procedure of Barnsley (1993) and Jacquin (see IEEE Trans. on Image Proc. vol.1, no.1, 1992) is presented. The new technique requires approximately one-third the encoding time of the previous method, thereby addressing a major obstacle to the widespread use of fractal-based algorithms. Search pools under the new scheme are segregated according to contrast distribution (not simply the degree of contrast) within each block, reducing the size of search areas, and hence the number of least-squares calculations required. A further refinement combining the benefits of searching-by-contrast with searching-by-distribution is introduced