Research On Fast Fractal Image Coding

FIC has attracted the attention of many native or abroad researchers since It was introduced into the field of image coding, due to its advantages, such as high compression performance, simple and fast decoding process, novel encoding and decoding theory and resolution independence.The main consuming time is the process of finding the best matched domain block in a large domain pool for a given range block, computing and quantizing the parameters and the process of image partition.This dissertation begins with the development, advantages and disadvantages of fractal image coding, and then introduces some improved FIC algorithms. The main contributions of this dissertation are as follows:â‘ According to the relationship between the variances of range blocks and domain blocks, a algorithm is proposed to improve Fisher's scheme. Experiment results show that the proposed algorithm needs less encoding time and have almost the same decoded image quality as Fisher's.â‘¡A fast fractal image coding algorithm based on FGSE is proposed in this dissertation. It can speed up the encoding process and keep the same decoded image quality. Nowadays, most improved fractal image coding algorithms are in the cost of the decrease of the decoded image. A fast optimal block matching in motion estimation named FGSE is featured by providing a sequence of fine grained boundary levels in an aim to reject a checking candidate as early as possible. A Lemma was introduced to describe the relationship between FIC and FGSE. And then FGSE can be used in the search process for the matched blocks in FIC.â‘¢A multiple descriptions coding algorithm based on fractal image coding is proposed in section five. Multiple descriptions coding (MDC) has emerged as an attractive framework for robust transmission over unreliable channels. In this thesis, FIC is introduced into MDC after transforming the parameters. Meanwhile, the fast fractal image coding algorithm based on FGSE introduced above is also used in the algorithm to speed up the image coding further.