说明：  这个有中文注释，看得明白，多元数据分析的主分量分析投影，包括最后计算压缩图像的峰值信噪比和压缩效果的源码。
( The Chinese have a comment, understand it, Principal component analysis of multivariate data analysis projection, Including the final calculation of the compressed image peak signal to noise ratio and compression of the source.)