Hybrid Fractal-wavelet Image Compression Algorithm with Variable Steps and Thresholds
Chunlin Song, Fuqiang Liu, Xi Chen · Jisuanji gongcheng · 2007
By studying the limitations of existing hybrid fractal-wavelet image compression methods,this paper proposes a novel hybrid fractal-wavelet image compression algorithm.Briefly,it adopts diverse error thresholds as well as searching steps,considering varied significance pertaining to coefficients of adjacent subband images with the same orientation but different frequencies,when fractal searching is made among them.Great searching steps along with small error thresholds applies to high frequency subbands,while the contrary is suitable for low ones.Theoretical analysis and experiment results indicate that this algorithm largely increases the compression rate and the speed of encoding without reducing SNR and quality of decoded images,which is superior to the traditional wavelet tree based algorithms of fractal image compression.