Fast fractal encoding in frequency domain
Fractal image compression applies the self-similarity property of an image. Much research has been done to study the properties of fractal coding in the image domain. In this paper, however, we try to explore the features of fractal coding in the frequency domain. We firstly overview the properties of fractal coding in the image domain, then we derive the corresponding formula of scaling factor and offset of affine transform in the DCT domain. Applying the energy compaction property of the DCT, we propose a fast fractal encoding algorithm by using only a small number of low frequency DCT coefficients in measuring the similarity between range block and domain block. We further propose a possible fast hybrid fractal encoding algorithm which combines existing fast search methods, statistical normalization and frequency domain comparison.