ssim

代码说明：

  是一種用以衡量兩張數位影像相似程度的指標。當兩張影像其中一張為無失真影像，另一張為失真後的影像，二者的結構相似性可以看成是失真影像的影像品質衡量指標。(Is a digital image to measure the similarity of two indicators. Two images when one of them is undistorted image and one for image distortion after the structural similarity between the two images can be viewed as a measure of the quality of the image distortion.)