为了提高分形图像编码算法的编码过程速度,首先从理论上证明了一个联系均方误差和相似度的不等式,并基于匹配对子块的相似度和domain块的标准差,设置了两个剔除条件,用来减少码书容量,然后通过缩小最佳匹配块的搜索范围,以达到加快编码速度的目的。对4幅复杂性不同的测试图像进行的仿真结果显示,在对解码图像主观质量影响很小的情况下,该方案大大加快了基本分形图像算法的编码速度。

In order to improve the speed of fractal image coding algorithm,this paper proved an inequality linking the root-mean-square(RMS) and similar measure mathematically and set up two kick-out conditions based on the similar measure and standard deviation of matched block.Therefore it can search out the best-matched block to a range block with a reduced search space at encoding process,which can shorten its runtime significantly.Computer simulation on 4 test images with different complexities demonstrate that the proposed scheme could speedup the coding process,while the subjective quality of the decoded image has a little degradation than that using the corresponding baseline fractal coding algorithm.