写一个计算PSNR值的MATLAB函数

以下是计算PSNR值的MATLAB函数：

function psnr_value = calculate_psnr(original_image, processed_image)
% Calculate PSNR value between two images

% Convert images to double precision
original_image = im2double(original_image);
processed_image = im2double(processed_image);

% Calculate MSE
mse_value = mean(mean((original_image - processed_image).^2));

% Calculate maximum pixel value
max_pixel_value = max(original_image(:));

% Calculate PSNR value
psnr_value = 10*log10(max_pixel_value^2/mse_value);
end

使用方法：

将原始图像和处理后的图像作为函数的输入参数，即可计算出PSNR值：

original_image = imread('original_image.png');
processed_image = imread('processed_image.png');
psnr_value = calculate_psnr(original_image, processed_image);
disp(['PSNR value is ', num2str(psnr_value)])