www.gusucode.com > 数字水印算法实现(matlab程序包),包含有DCT水印嵌入算法源码程序 > watermark综述+代码/psnr.m
%Name: Chris Shoemaker %Course: EER-280 - Digital Watermarking %Project: Calculates the PSNR (Peak Signal to Noise Ratio) % of images A and A', both of size MxN function [A] = psnr(image,image_prime,M,N) % convert to doubles image=double(image); image_prime=double(image_prime); % avoid divide by zero nastiness if ((sum(sum(image-image_prime))) == 0) error('Input vectors must not be identical') else psnr_num=M*N*max(max(image.^2)); % calculate numerator psnr_den=sum(sum((image-image_prime).^2)); % calculate denominator A=psnr_num/psnr_den; % calculate PSNR end return