test2.m

A Survey of Techniques for Digital Watermarking。Watermarking综述

A = double(imread('lena.bmp'));
figure(1);
imshow(uint8(A));
imgsize = size(A,1)*size(A,2);
seed = 123;
rand('state',seed);
pn=rand(size(A,1),size(A,2));
AW = A + pn ;
figure(2);
imshow(uint8(AW));
figure(3);
imshow(uint8(pn));
cor1 = sum(sum(pn.*A))