本文介绍的是一种改进的SPIHT算法，是基于图像编码的小波系数块的，它主要是把四个系数分成一个块，与阈值比较，分出重要与非重要，在进行编码。-This article is a modified SPIHT algorithm is based on the wavelet coefficients of image coding block, it is mainly divided into the four coefficients of a block, compared with the threshold value, separate the important and non important, during the encoding.