说明：  Matlab中实现SSIM算法，选取合适图片添加不同噪声，然后用三种去噪算法分别对添加噪声后的图片进行去噪，用SSIM图像相似度指标分析不同去噪算法对不同噪声的去除效果。
(SSIM algorithm to achieve the Matlab, select the appropriate image with different noise, and then used to add noise after image denoising respectively three denoising algorithms, the effect of different denoising algorithm to remove noise of different SSIM image similarity index analysis.)