说明：  用MatLab实现图像压缩。以真彩图像的处理为例，对由它转换来的彩色索引矩阵进行二进小波多层分解，对低频近似的系数矩阵作相应的截取处理，以及优化索引图像的彩色图。
(Realize image compression using MatLab. To deal with true color images for example, by its conversion to the color index matrix dyadic wavelet decomposition of multi-storey, low-frequency approximation of the coefficient matrix for the corresponding interception treatment, as well as the optimization of image color map index.)