Greylevel Difference Classification Algorithm in Fractal Image Compression

This paper proposes the notion ofa greylevel difference classification algorithm in fractal imagecompression. Then an example of the greylevel difference classificationalgorithm is given as an improvement of the quadrant greylevel and varianceclassification in the quadtree-based encoding algorithm. The algorithmincorporates the frequency feature in spatial analysis using the notion ofaverage quadrant greylevel difference, leading to an enhancement interms of encoding time, PSNR value and compression ratio.