基于感兴趣区的图象近无损压缩

无损感兴趣区（Lossless Region of Interest (ROI)图象压缩方法，即在感兴趣区采用无损压缩，而在其他区域采用有损压缩，从而保证了重要信息不丢失，并尽可能提高衅象的压缩比，在整形小波变换（IWT）和嵌入式零树编码的基础上，实现了无损感兴趣区（Lossless ROI)的图象近无损压缩，并提出了一种小波变换域形状编码算法－－树映射形状编码，同时给出了算法的原理及实现，并进行了相关实验，实验结果表明，该算法能够提高压缩效率，且压缩效率取决于感兴趣区的大小以及对不感兴趣区图象的质量要求。

Near-Lossless Image Compression Based on Lossless Regions of Interest(ROI)

Image compression based on Lossless Region of Interest (ROI) means to compress interesting regions in an image without loss, and to compress uninteresting regions with a little loss. Based on this idea a high compression ratio can be obtained and the important information can be preserved losslessly. In this paper, the near lossless image compression is implemented, based on Integer Wavelet Transform(IWT) and embed zero tree coding scheme. In addition, the tree mapping shape coding scheme is proposed. In this paper the IWT and embed zero tree coding scheme are introduced simply, then the tree mapping shape coding algorithm are presented in detail, finally the experimental results are presented and compared with the results of lossless compression. Experimental results represent that the algorithm can obtain much higher compression ratio than lossless compression algorithms, but the improvement of compression ratio is related to the size of ROI and quality of uninteresting regions.