中文摘要：

针对原SPIHT算法存在扫描的重复且未能充分利用小波系数分布特点,随着压缩比的增加,会引起编码效率的下降等不足,提出一种改进的图像压缩编码算法。改进的图像编码算法低频子带进行DPCM无损编码,高频子带采用优化排序的SPIHT算法。仿真结果表明,改进算法较原算法在重构图像的主观效果和峰值信噪比上都得到了提高。

英文摘要：

Due to the repeated scanning and not being able to make full use of distribution characteristic of wavelet coefficient,coding efficiency will decrease along with the increasing of compression ratio,we propose an modified algorithm.The modified algorithm uses DPCM （Difference Pulse Code Modulation） coding for the lowest frequency subband and optimizes sorting pass of SPIHT for the high frequency subband.Experimental results demonstrate that the subjective quality and the peak SNR of the reconstruction image are all raised.