Use of Wavelets in Fractal Compression Algorithm for Enhanced Performance

Fractal coding suffered from low coding efficiency, difficulties to obtain high quality encoding of images, and blocking artifacts at low bit rates and exhaustive inherent coding time. Blocking artifacts can be avoided if fractal coding is performed in the wavelet domain. A new fast and efficient image coder is developed that applies the speed of the wavelet transform to the image quality of the fractal compression. Fast fractal encoding using Fisher’s domain classification is applied to the low pass subband of wavelet transformed image and a modified Set Partitioning In Hierarchical Trees (SPIHT) coding on the remaining coefficients. Furthermore, image details and wavelet progressive transmission characteristics are maintained, no blocking effects from fractal techniques are introduced, and the encoding fidelity problem common in fractal-wavelet hybrid coders is solved. This scheme promotes heavy reduction in encoding-decoding time compared with the pure accelerated Fractal coding results. This method is compared with SPIHT wavelet coding. In both cases, the new scheme improves the subjective quality of pictures for high-medium-low bit rates.