Greylevel Difference Classification Algorithm inFractal Image Compression
Greylevel Difference Classification Algorithm in Fractal Image Compression

This paper proposes the notion of a greylevel difference classification algorithm in fractal image compression. Then an example of the greylevel difference classification algorithm is given as an improvement of the quadrant greylevel and variance classification in the quadtree-based encoding algorithm. The algorithm incorporates the frequency feature in spatial analysis using the notion of average quadrant greylevel difference, leading to an enhancement in terms of encoding time, PSNR value and compression ratio. This work is supported by the National Natural Science Foundation of China (No.69903006).