A Quad tree classified based fractal image coding approach
Xue Wang · Journal of Changchun Post and Telecommunication Institute · 1999
A Laplacian operator used for Quad tree classifitions is introduced. It can make more accurate and objective classifications and solve the problems of big error in some range blocks. Compared with the Jacquin's method, the proposed approach can raise the PSNR by 2 56 dB under the condition of a higher compression ratio.