FAST FRACTAL IMAGE ENCODER DESIGN

Abstract

Fractal theory has been widely applied in the filed of image compression due to the advantage of resolution independence, fast decoding, and high compression ratio. However, it has a fatal shortcoming of intolerant encoding time because that every range block is need to find its corresponding best matched domain block in the full image. Therefore, it has not been widely applied as other coding schemes in the field of image compression. In this paper, an algorithm is proposed to improve this time-consuming encoding drawback by the adaptive searching window, partial distortion elimination and characteristic exclusion algorithms. Proposed can efficient decrease the encoding time significantly. In addition, the compression ratio is also raised due to the reduced searching window. Conventional fractal encoding for a 512 by 512 image need search 247009 domain blocks for every range block. Experimental results show that our proposed method only search 120 domain blocks which is only 0.04858% compared to conventional fractal encoder for every range block to encode Lena 512 by 512 8-bit gray image at the bit rate of 0.2706 bits per pixel (bpp) while maintaining almost the same decoded quality as conventional fractal encoder does. This paper contributes to the research of encoder of fast image communication system.