说明：  ％本程序功能是计算2幅彩色图像的PSNR,以此来评价图像处理的效果％％％％％％％％％ ％ 运行的结果保存在变量PSNR中
( This program features the calculation of two color images of the PSNR, in order to evaluate the effect of image processing the results of running stored in variables in PSNR)