RS方法分析BMP图片嵌入率

function rate=RSana(input) %输入为512*512的图片--RSana('00002.bmp') W = imread(input); W = double(W); W=W(:)'; % 将像素矩阵转化为一维数组 [m,n] = size(W); k = n/4; asd = W; R = zeros(2, 4); %用来存储两组RS的四个值 M = [1;0;0;1]; %用来实现随即翻转 bloc = zeros(4, 1); for j = 1 : k %做非负和非正翻转，再计算相关性 bloc=asd((j-1)*4+1:j*4); %每四个像素放在一起 summ(1) = Abf(bloc); summ(2) = Abf(posturn(bloc,M)); summ(3) = Abf(negturn(bloc,M)); if summ(2) > summ(1) %Rm R(1,1) = R(1,1) + 1; end if summ(2) < summ(1) %Sm R(1,2) = R(1,2) + 1; end if summ(3) > summ(1) %R_m R(1,3) = R(1,3) + 1; end if summ(3) < summ(1) %S_m R(1,4) = R(1,4) + 1; end end asd = posturn(asd, ones(n, 1)); %先对载体全做正翻转，接着做非负和非正翻转，再计算相关性 for j = 1 : k bloc=asd((j-1)*4+1:j*4); summ(1) = Abf(bloc); summ(2) = Abf(posturn(bloc,M)); summ(3) = Abf(negturn(bloc,M)); if summ(2) > summ(1) %Rm R(2,1) = R(2,1) + 1; end if summ(2) < summ(1) %Sm R(2,2) = R(2,2) + 1; end if summ(3) > summ(1) %R_m R(2,3) = R(2,3) + 1; end if summ(3) < summ(1) %S_m R(2,4) = R(2,4) + 1; end end R = R/k; y = (R(1,3)-R(1,4))-(R(1,1)-R(1,2)); dpz = R(1,1) - R(1,2); dpo = R(2,1) - R(2,2); dnz = R(1,3) - R(1,4); dno = R(2,3) - R(2,4); C = [2 * (dpo + dpz), (dnz - dno - dpo - 3 * dpz), (dpz - dnz)]; r = roots(C); p = r./(r - 0.5); rate=p(2);