A new approach for the speed up of fractal image coding

We propose a time improved fractal image coder with a reduced domain pool and optimal luminance transform parameters calculation. This scheme is applicable to the Fischer´s (1994) classification method. We accelerate the encoding process by reducing the domain pool and then by minimizing the number of operations for the similarity search; this reduction is based on discarding the domains with nearly the same variance from each class of the domain pool. This approach provides a greater speed loss with a slight loss in the compression ratio and a slight improvement in the image quality. In our experiments an acceleration of 6.7 for the image “Lena” is reached with a good decoded image quality. For a speed up factor of 2 the compression ratio is about 0.8% reduced and the image quality is about 0.23% improved. In order to increase the compression ratio again we use Jaquin´s (1992) method and we remove some of the range blocks with shade property from the search