SSIM的matlab代码

SSIM（结构相似性指数）是一种用于测量两个图像之间的相似度的指标。以下是一个用MATLAB编写的计算SSIM的代码示例：

function ssimval = ssim(img1, img2)

% convert images to double precision
img1 = im2double(img1);
img2 = im2double(img2);

% constants for SSIM calculation
K1 = 0.01;
K2 = 0.03;
L = 1;
C1 = (K1*L)^2;
C2 = (K2*L)^2;

% mean and variance of images
mu1 = mean2(img1);
mu2 = mean2(img2);
sigma1 = std2(img1);
sigma2 = std2(img2);
covariance = cov(img1(:), img2(:));

% SSIM formula
numerator = (2*mu1*mu2 + C1)*(2*covariance(1,2) + C2);
denominator = (mu1^2 + mu2^2 + C1)*(sigma1^2 + sigma2^2 + C2);
ssimval = numerator / denominator;
end

该函数接受两个图像作为输入参数，并返回它们之间的SSIM值。该代码中包括了SSIM计算公式的所有参数和常量，以及计算平均值，方差和协方差的代码。