【图像隐藏】基于DCT的数字图像水印防伪附matlab代码

clc, cleara = imread('fig11.jpg');% 原图像% a = rgb2gray(a);% 图像灰度化a = im2double(a);% 将数据转换为doubletmp_a = a;a = a(:,: ,2);[M1, N1] = size(a);knum1 = M1 / 8;% 将图像划分成8 * 8的子块knum2 = N1 / 8;b0 = imread('fig9.png'); % 水印图像b = rgb2gray(b0);b = im2double(b);subplot(1, 2, 1)imshow(tmp_a)title('原图像')subplot(1, 2, 2)imshow(b)title('水印图像')alpha = 0.18; %水印的嵌入强度mask1 = [1 1 1 1 0 0 0 0;% 低频掩膜矩阵         1 1 1 0 0 0 0 0;         1 1 0 0 0 0 0 0;         1 0 0 0 0 0 0 0;         0 0 0 0 0 0 0 0;         0 0 0 0 0 0 0 0;         0 0 0 0 0 0 0 0;         0 0 0 0 0 0 0 0];ind1 = find(mask1 == 1);mask2 = [0 0 0 0 1 1 0 0;         0 0 0 1 1 0 0 0;         0 0 1 1 0 0 0 0;         0 1 1 0 0 0 0 0;         1 1 0 0 0 0 0 0;         1 0 0 0 0 0 0 0;         0 0 0 0 0 0 0 0;         0 0 0 0 0 0 0 0];% 中频掩膜矩阵ind2 = find(mask2 == 1);[M2, N2] = size(b);L = M2 * N2;knum3 = ceil(M2 * N2 / 11);% 将水印图像按11个像素点一块分的块数b = b(:);% 水印图像列向量化b(L + 1 : 11 * knum3) = 0;% 补0T = dctmtx(8);% DCT变换矩阵ab = zeros(M1, N1);% 嵌入水印后的图像初始化k = 0;for i = 0 : knum1 - 1    for j = 0 : knum2 - 1        xa = a(8 * i + 1 : 8 * i + 8, 8 * j + 1 : 8 * j + 8);% 原图像的一个8 * 8子块        ya = T * xa * T';% 作DCT变换        coef1 = (mask1 + mask2) .* ya;% 提取中低频系数        if (k < knum3)            coef1(ind2) = coef1(ind2) + alpha * b(11 * k + 1 : 11 * k + 11);        end        ab(8 * i + 1 : 8 * i + 8, 8 * j + 1 : 8 * j + 8) = T' * coef1 * T;% 作DCT逆变换得到合成图像        k = k + 1;    endendacha = ab - a;% 合成图像和原图像的差k = 0;tb = zeros(11 * knum3, 1);% 提取的水印图像初始化for i = 0 : knum1 - 1    for j = 0 : knum2 - 1        xa2 = acha(8 * i + 1 : 8 * i + 8, 8 * j + 1 : 8 * j + 8);% 提取差图像的一个8 * 8子块        ya2 = T * xa2 * T';% DCT变换        coef2 = mask2 .* ya2;% 仅提取中频系数        if k < knum3            tb(11 * k + 1 : 11 * k + 11) = (1 / alpha) * coef2(ind2);% 还原水印信息        end        k = k + 1;    endendtb(L + 1 : end) = [];% 去掉补的0tb = reshape(tb, [M2, N2]);% 把列向量变回矩阵tmp_aa = tmp_a;tmp_aa(:,:,2) = ab;figure, subplot(1, 2, 1)imshow(tmp_aa)title('嵌入水印后的图像')subplot(1, 2, 2)imshow(tb)title('提取的水印图像')std = 0.005;type = "gaussian";% 噪声类型g = imnoise(tmp_aa, type , std);tmp_g = g;g = g(:,:,2);acha = g - a;% 合成图像和原图像的差k = 0;tb = zeros(11 * knum3, 1);% 提取的水印图像初始化for i = 0 : knum1 - 1    for j = 0 : knum2 - 1        xa2 = acha(8 * i + 1 : 8 * i + 8, 8 * j + 1 : 8 * j + 8);% 提取差图像的一个8 * 8子块        ya2 = T * xa2 * T';% DCT变换        coef2 = mask2 .* ya2;% 仅提取中频系数        if k < knum3            tb(11 * k + 1 : 11 * k + 11) = (1 / alpha) * coef2(ind2);% 还原水印信息        end        k = k + 1;    endendtb(L + 1 : end) = [];% 去掉补的0tb = reshape(tb, [M2, N2]);% 把列向量变回矩阵tmp_aa = tmp_a;tmp_aa(:,:,2) = g;figure, subplot(1, 2, 1)imshow(tmp_g)title('添加噪声后的图片')subplot(1, 2, 2)imshow(tb)title('提取的水印图像');