摘要：针对基本分形图像编码算法时间过长的问题，提出了一种基于与中间块比较的快速分形编码算法。该算法是对基于形态特征的快速分形图像编码算法的改进，将形态特征意义下的最近邻匹配改进为与中间块的误差意义下的最近邻匹配，并且在最近邻的邻域内进一步搜索最优匹配父块时，对各父块进行8种等距变换，而不是在找到最优匹配父块后进行，同时引进误差阈值来控制子块搜索的邻域范围。实验结果表明，该算法编码速度大大提高，并且在相近编码时间的前提下该算法的解码图像质量比基于形态特征的算法好。

Abstract：In order to solve the problem of time consuming in the encoding process of the basic fractal algorithm, a faster method based on the comparison with a preset block is proposed, which is an improvement of the fast fractal image encoding algorithm based on shape feature: the nearest domain block to a range block is found in the sense of comparing with a preset block instead of shape feature. When searching for the best domain block in the vicinity of the nearest domain block, the eight isometric transformations are applied on every domain block instead of only on the best one. At the same time, an error threshold is used to control the searching area around the nearest domain block. The experimental results demonstrate that the proposed algorithm is much faster than the basic fractal algorithm and the quality of decoded image is better than the image processed by shape feature based algorithm in the premise of same encoding time.