Speeding up fractal image encoding by wavelet-based block classification

The authors propose a novel fast fractal image encoding algorithm using wavelet-based block classfication. The range blocks and corresponding domain blocks are classified into edge selective categories by the energy compacted wavelet coefficients. The searching is carried out between the same classes for range-domain comparisons which significantly reduces the computational complexity. Experimental results show that the proposed method can speed up the fractal image encoding process by up to 12.3 times over the conventional full search method.