一种基于改进嵌入小波编码的新图象压缩算法

A Image Compression Algorithm Based on New Embedded Wavelet Coding

基于逐次逼近量化与零树结构的嵌入零树小波编码 (EZW)被认为是静态图象变换编码领域迄今为止最好的压缩算法之一 .然而通过分析和实验 ,发现该算法在一定程度上存在时间复杂度较高和复原图象质量不尽理想等不足 .本文提出了一种基于改进嵌入小波编码的新图象压缩算法 ,该算法能够通过以下 3项措施提高 EZW算法工作效率 :(1)对最低频子带进行单独编码 ;(2 )采用全新的嵌入小波编码策略 ,不再利用导致计算量剧增的双亲—子女 (Parent-Children)关系 ;(3 )进行嵌入小波编码时 ,不再考虑 ZTR(零树根 )和 IZ(孤立零 )符号 .实验结果表明 :本文提出的新图象编码算法在压缩 /解压缩速度、图象复原质量等方面均明显优于

The well known embedded zerotree wavelet(EZW)coder uses successive approximation quantization(SAQ)process and zerotree structure of wavelet coefficients. The EZW coder scans iteratively whole wavelet coefficients during the SAQ process by using the parent children relation of the coefficients to multiresolution image decomposition, which deceases the coding efficiency considerably. In this paper, a new fast and efficient embedded image coding is presented. In our proposed scheme, the parent children relation is not used and also ZTR and IZ symbols are not considered for coding. Therefore the time consuming problem can be avoided. Experimental results show that our proposed coding method performs better than that of EZW in the aspects of PSNR, encoding time and decoding time.