Abstract: Fractal code is used to describe the image similarity in scales redundancy information.In this paper,the image features are recorded as fractal codes that are used to determine the image similarity and retrieval.Based on the self-adaptive method of quadtree segmentation,a new fast fractal image coding method was presented.In this method,fractal codes are gotten quickly from the similarity determination of fixed blocks within neighborhood.The segmentation is decreased and the coding time is reduced with ensuring the quality of image decoding.Meanwhile,the paper also proposed a new distance formula by which the image similarity between blocks can be quickly determined and the accuracy of the image similarity judgment can be enhanced. The experimental results show that compared with the grayscale histogram method,the proposed algorithm significantly improve the accurate-complete rating of image retrieval.Compared to the fractal retrieval algorithm in literature,the algorithm shortens the encoding time and reduces the number of sub-blocks,thereby improves retrieval efficiency.

Key words: Fractal code,Self-adaptive quadtree,Image retrieval,Contiguous-match