www.gusucode.com > 小波变换的数字水印matlab源码程序 > new_wavelet/psnr.m

    %By:		LiuYu
%Course:	Digital Watermarking
%Project: 	Calculates the PSNR (Peak Signal to Noise Ratio)
%            of images A and A', both of size NxN

function [PSNR] = psnr(I,II)

    % convert to doubles
    
    x=double(I);
    X=double(II);
    N=size(x,1);
    PSNR=10*log10(N*N*255^2/sum(sum((x-X).^2))) 
    
return