关键词: 分形图像编码, 图像压缩, 2－范数

Abstract: Although fractal image compression has high quality at high compression ratio，it needs a lot of encoding time so that it has not been widely applied as other coding schemes in the field of image compression.In this paper，a fast algorithm for fractal image coding based on two-norm is proposed to improve this drawback.By sorting the blocks in the codebook according to their two-norms，the encoder uses the bisection search method to find out the nearest codebook block to an input range block in the sense of two-norm.After that，the encoder further visits the codebook blocks in the vicinity of the nearest codebook block in order to search out the best-matched codebook block to the range block being encoded.Computer simulation results show that the proposed scheme not only significantly reduces the encoding time，but also provides the same image quality as baseline fractal coding algorithm with full search.

Key words: fractal image coding, image compression, two-norm