数据压缩字典与快速图像分形映射压缩算法

针对分形编码压缩时间太长、以至于该算法很难达到实用的缺点,提出了对图像进行分级预处理,即根据被压缩图像的实际情况建立一个数据压缩字典,使得被压缩图像的匹配块仅在数据压缩字典指定的块中进行,从而大大减少图像压缩过程中的搜索范围和压缩时间·此外,给出了建立数据压缩字典的理论基础,并根据此思想给出了一个新的实现分形编码算法·实验表明,在提高压缩比的同时,运算时间也大大缩短

Data Compression Dictionary and a Quick Image Compression Algorithm Based on Fractal Mapping

The compression time of fractal coding algorithm is so long that the algorithm is hardly useful in reality. The idea to preprocess the image by means of many grey levels was presented. It constructs a data compression dictionary based on compressed image, so that the compression block matched in the image is only searched in the data compression dictionary. As a result, this algorithm greatly shortens the compression time and the searching scope in the compression procedure,compared with other algorithms of the fractal block coding. In addition, the theoretical basis of constructing the data compression dictionary was obtained. Based on the new compression idea, a concrete algorithm of realizing fractal image coding was designed. The new algorithm can improve compression ratio while reducing encoding time.