A modified fractal transformation to improve the quality of fractal coded images

The discrete fractal transformation has recently emerged as a powerful technique for coding images. The scheme works by dividing an image into blocks and making use of a contraction mapping by which the domain blocks are mapped into range blocks. During this process it is usual to filter the domain blocks. In this work, we show how a change in the filtering procedure can improve the image quality of fractal coding methods based on the mentioned transformation. After a presentation of the discrete fractal transformation, we explain the change and apply it to the quadtree-based fractal scheme obtaining improvements in PSNR that can reach 1 dB when compared with the results obtained by traditional filtering