Astronomical Image Compression Algorithm And Realization

With CCD technology rapplid development, astronomical images are increasingly larg e, vast amounts of astronomical image data to the storage and network transmission enorm ous pressure. Because the astronomical image contains a large number of precise informa tion to astronomical research are valuable, they need lossless compression. At present most of astronomical image lossless compression using common compression software, the effe ct is not good enough, so the research of a more suitable compression method for astronom ical images is undoubtedly significant.This paper firstly describes the basis theoretical of image compression,given a detailed description of the implementation principle of Huffman coding, LZW coding and predictti ve coding. Then introduced the wavelet transform theory, expounded the second generation of integer wavelet transform theory and implementation steps based on lifting scheme; and compared These technologies with experimental methods,pointed out that an important pro spects for hybrid coding. Then analyzed and summarized characteristics of astronomical images-large,special format,high gray and Noisy. In order to solve the problem of high Gra y, this paper use Gray image stretching technology to achieve astronomical images display; After analysis the experiment results of Predicting and IWT,with predecessors of thought, this paper proposed a new Subblock DPCM and integer wavelet transform using in astrono mical image lossless compression algorithm. and it has done a comprehensive exposition of the algorithm, the importance of Astronomical images sub-block is discussed in detail, the DPCM prediction strategy is selected by experiment, and selected the (5,3) wavelet as the wavelet and symmetric extension of the wavelet transform boundary approach.After the detailed introduction the implements of the method,The author implemented a prototype on vc++6.0. The experimental results indicated that the compression ratio of SubBlock DPCM and IWT algorithm is about 29%,26%,2% higher than that of PKZip, WinZip and WinRar respectively on average, compression speed is much more quick than WinZip and WinRar. Proved that the method is an effective and fast one on astronomy.