结构相似性，是一种衡量两幅图像相似度的指标。该指标首先由德州大学奥斯丁分校的图像和视频工程实验室(Laboratory for Image and Video Engineering)提出。SSIM使用的两张图像中，一张为未经压缩的无失真图像，另一张为失真后的图像。(Structural similarity is a measure of the similarity between two images. The target was first presented by the Labor