基于规范子块五点和的快速分形图像编码.pdfVIP

计算机研究与发展 ISSN 1000—1239／CN 11-1777／TP Journal of Computer Research and Development 44(12)：2066～2071，2007 基于规范子块五点和的快速分形图像编码 何传江 刘维胜 申小娜 。(重庆大学数理学院 重庆 400030) (重庆通信学院 重庆 400035) (chuanjianghe@sina．corn) Fast Fractal Image Coding Based on Quincunx Sums of Normalized Blocks He Chuanjiang ，Liu Weisheng 一，and Shen Xiaona 。(College of Mathematics and Physics，Chongqing University，Chongqing 400030) (Chongqing Communication College，Chongqing 400035) Abstract Fractal image coding can provide a high decoded image quality at a high compression ratio，but it requires traditionally a very long runtime in the encoding process．Therefore，it is essential to develop fast encoding algorithms before it could be widely used for various applications．The encoding time is mostly spent on searching for the best—matched block to an input range block in a usually．1arge domain pool；a new scheme is thus proposed to limit the search space in this paper．It first defines a new feature，quincunx sum，which iS the intensities sum of a normalised image block over each corner of the block and one at the centre．Then，the quincunx sum is utilized to confine efficiently the search space to the vicinity of the initial—matched block(i．e．，the domain block having the closest absolute quincunx sum to that of the input range block being encoded)．Experimental results show that this method can reduce drastically the amount of range—domain comparisons needed to encode each range block．The proposed algorithm has also been compared with the fast fractal encoding algorithm based on cross—trace，showing that under the same search neighborhood it performs better in terms of encoding time，image quality and compression rate． Key words image compression；fractal；iterated function system；fractal image coding；quincunx sum 摘 要 分形图像编码通常需要较长的时间，编码时间主要花费于在一个海量