一种基于小波零树的彩色图像编码算法

为提高基于分层树的集合分割算法(SPIHT)的编解码速度,对算法结构重新设计,提出了一种简单的无链表小波零树编码算法.通过预处理和主处理过程实现了流水线编码结构,减少了存储器的访问频率.预处理完成对所有节点显著性的标注,主处理完成无链表的零树编码.对彩色图像编码时首先进行RGB空间到YUV空间的变换,然后在比特平面扫描过程中,依次对YUV三个平面进行编码,这样输出的码流是完全嵌入式的.一般情况下,亮度分量的最高显著平面都高于色度分量.因此通过色度分量输出控制策略,可以进一步提高算法对彩色图像的编码性能.硬件实现结果表明,改进后算法的编解码速度明显提高,而率失真性能并没有下降,所以新算法特别适合高分辨率或不规则图像的编解码芯片设计.

Algorithm for color image coding based on wavelet zerotree

To improve the coding speed of set partitioning in hierarchical trees (SPIHT) al gorithm, the structure of SPIHT was re-designed, a simple listless coding algor ithm based on wavelet zerotree was developed. Pipeline coding structure was real ized by pre-processing and main-processing processes and access frequency was reduced. Pre-processing was designed to mark the significance of all nodes and main-processing to finish listless zerotree coding. In color image coding, the transform from RGB(red-green-blue) space to YUV (luminance-chrominance) space was performed, YUV color planes was correspondingly coded on bit plane sorting. So, the output coding stream was fully embedded. Generally, t he first significant bit plane of luminance component is higher than chrominance component's. The performance of color image coding is further improved by outpu t-controlled policy of chrominance component. Hardware implementation results s how that the speed of codec is improved significantly, but rate-distortion perf ormance is not reduced. The new algorithm is especially suitable for high resolu tion or irregular image codec chip design.