图像隐藏DCT的数字图像水印防伪附matlab代码

clc, clear
a = imread('fig11.jpg');% 原图像
% a = rgb2gray(a);% 图像灰度化
a = im2double(a);% 将数据转换为double
tmp_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0
T = 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;
    end
end
acha = 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;
    end
end
tb(L   1 : end) = [];% 去掉补的0
tb = 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;
    end
end
tb(L   1 : end) = [];% 去掉补的0
tb = 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');