分形图象压缩的两步匹配法  

TWO STEP MATCHING APPROACH FOR FRACTAL IMAGE ENCODING

作　　者：袁乔岳 杨士强[1] 

机构地区：[1]清华大学计算机科学与技术系

出　　处：《小型微型计算机系统》1999年第4期292-295,共4页Journal of Chinese Computer Systems

基　　金：国家高科技发展计划

摘　　要：分形图象压缩是一种新颖有效的压缩技术，与其它方法相比较压缩比高、解码速度快，但是压缩编码非常耗时．本文介绍的两步匹配法可以明显的减少编码时间．这种方法在处理压缩过程中的Ｄｏｍａｉｎ块与Ｒａｎｇｅ块的匹配时采用了两步而不是原来的一步．它与Ｆｉｓｈｅｒ和Ｊａｃｏｂｓ提出的经典方法相比，图象质量几乎不降低（降低约０．１ｄＢ）。Fractal image compression is a relatively new and effective technique with a high ratio and short decoding time. However, the disadvantage is explicit as the time consumed in the encoding procedure is enormous. Here we developed a new encoding approach, which gains drastic improvement in speed, compared with the typical method(by Fisher and Jacobs). The essence of the algorithm is two step matching rather than one step, while comparing domains with a range. In the first step, the sizes of domains and the range are shrunk by half, so the comparison is much less complicated. We can then get some candidate domain blocks(CDBs) which are more near to the range. In the second step, we compare the CDBs with the same range of the original size. We can select the most matched domain from CDBs.Both of the steps are very simple. As a result, the total time spent in two steps is even shorter than one step method. Experiments show that the improved algorithm is 2 to 4 times faster than the typical one(by Fisher and Jacobs). Furthermore, the quality of the recovered images is almost as same as that acquired from the typical method, with 0.1dB reduction at the most.

关 键 词：图象压缩 分形 两步匹配法 图象处理 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]