Wavelet Transform-based Still Image Compression Coding Technology

With the extension of image application,some new image compression and coding techniques which can not only achive high compression ratio and definition but also meet such demands by Progressive Transmission,and other applications are needed. Therebefore, compression and coding technique in image and video becomes a hot point in image research field.In this paper, the digital image compression techniques based on wavelet transform are analyzed and summarized, the current state of the techniques is introduced and several directions of development are proposed. Some important problems such as the arichitecture of wavelet coder, the coding step and how to choose wavelet basis are discussed, some simulations with matlab wavelet toolbox is made to demonstrate. A conclusion that the difference in performance between orthnorgal wavelets and biorthnorgal wavelets were not as largr as we desired when they have familiar mathematical properties is also made.This paper proposes an improved EZW algorithm based on Partition-transform-Merge computation. Stronger coupling and pipelining between the transform and the coding stages is made possible. The algorithm computes the sub_band_max for each sub-band as a by-product of the Partition-transform-Merge computation to improve the zero-tree checking process and reduce the computing complexities.An extensive research on static image compression is presented in this paper. On the basis theoretical above, programming achieves corresponding algorithm, experimental results show that our new algorithm actually improves the execution time .