The algorithm of fractal image block coding based on the ortho difference sum

According to the relationship between matching mean square error and ortho difference sum, range can find the best matching defined-domain within the narrower scope of search. At the same time, the defined-domain having smaller standard deviation will be excluded within the entire codebooks previously and all the ranges having smaller standard deviation will be substituted by their mean values during the decoding process. The experiments show that, the algorithm that I have come up with in this essay improves respectively four times and six times in coding speed compared with cross-track algorithm and variance algorithm, meanwhile, the peak's signal-noise ratio of the decoded images is slightly improved.