shuiyin.rar_477_little_watermark 水印检测和提取

clc clear all k = 20; block_size = 8; DCT_coef = [0,0,0,1,1,1,1,0; 0,0,1,1,1,1,0,0; 0,1,1,1,1,0,0,0; 1,1,1,1,0,0,0,0; 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]; orig_image = double(imread('woman2.jpg'));%原始图像 orig_image_show = orig_image;%用于显示原图 [Hc,Wc] = size(orig_image); c = Hc/8; d = Wc/8; m = c*d;% 将原图分为m个8*8块 watermark = double(imread('cmc.png'));%水印图像,白色为目标 watermark_show = watermark;%用于显示水印 [Hm,Wm] = size(watermark);%水印尺寸 n = Hm*Wm;%水印图像总像素点n %reshape将水印按列重组为一维向量 %round将序列四舍五入，通过除以256将watermark转为0（背景）、1（目标）二值 watermark = round(watermark./256); watermark = reshape(watermark,1,Hm*Wm); xx = 1; mean = zeros(1,c*d);%预先分配内存 variance = mean;%预先分配内存 %求方差 for j = 1:c for i = 1:d mean(xx)=1/64*sum(sum(orig_image(((1+(j-1)*8):j*8),((1+(i-1)*8):i*8)))); variance(xx)=1/64*sum(sum((orig_image(1+(j-1)*8:j*8,1+(i-1)*8:i*8)-mean(xx)).^2)); xx = xx+1; end end %将方差升序排列存于A，长度为c*d,即子块数m A = sort(variance); % 16506 A = fliplr(A);%最终降序排列 %取出方差最大的前n块，长度为n，即水印像素数 B = A(1:n); %标记水印信息到方差最大的前n块 variance_o = zeros(1,c*d); for g = 1:n for h = 1:c*d if B(g) == variance(h) variance_o(h) = watermark(g); h = c*d; end end end watermark_vector = variance_o; watermarked_image = orig_image;%准备嵌入的图像 %设置MATLAB随机数生成器状态J,作为系统秘钥K %MATLAB只要知道初始状态，就确定唯一的伪随机序列 rand('state',7); %根据当前的随机数生成器状态，生成0、1的伪随机序列，长度为22 %用于将水印置乱，提升鲁棒性 pn_sequence_zero = round(rand(1,sum(sum(DCT_coef)))); %嵌入水印 x=1; y=1; for kk=1:m %一共m个子块 %分块DCT变换 dct_block = dct2(orig_image(y:(y+block_size-1),x:(x+block_size-1))); %纹理大并且被标示的水印信息为1（目标）的块在DCT中频系数嵌入伪随机序列 zz=1; if watermark_vector(kk)==1; for ii=1:block_size for jj=1:block_size if (DCT_coef(jj,ii)==1) dct_block(jj,ii)=dct_block(jj,ii)+pn_sequence_zero(zz)*k; zz=zz+1; end end end end %分块DCT逆变换 watermarked_image(y:(y+block_size-1),x:(x+block_size-1))=idct2(dct_block); if (x+block_size)>Wc x=1; if(y+block_size)>Hc y=1 else y=y+block_size; end else x=x+block_size; end end watermarked_image_int=uint8(watermarked_image); %生成并输出嵌入水印后的图像 imwrite(watermarked_image_int,'dct2_A.jpg','jpg'); %显示嵌入水印后的图像 figure(1); subplot(131) imshow(orig_image_show,[]) xlabel('原图像'); subplot(132) imshow(watermark_show,[]); xlabel('水印图像') subplot(133) imshow(watermarked_image_int,[]); xlabel('嵌入水印后的图像') disp('水印图像PSNR'); myPSNR=func_PSNR(watermarked_image_int,orig_image_show) disp('对含水印图像进行JPEG压缩'); imwrite(watermarked_image_int,'JPEG_attack.jpg','jpeg','Quality',45); %最后的这个参数为压缩强度，其值越大压缩程度越小，提取出的水印效果越好 ImgWm=imread('JPEG_attack.jpg'); %本次实验加噪强度调节范围为30:5:60值，其中强度为49、50、51的地方有畸变 figure(2); subplot(131) imshow(orig_image_show,[]) xlabel('原图像'); subplot(132) imshow(watermarked_image_int,[]); xlabel('嵌入水印后的图像') subplot(133) imshow(ImgWm,[]); xlabel('进行JPEG压缩后的图片') disp('对含水印图像进行JPEG压缩PSNR'); myPSNR=func_PSNR(ImgWm,orig_image_show) disp('对含水印图像加高斯噪声'); ImgWm=imnoise(ImgWm,'gaussian', 0, 0.001); %对含水印图像加高斯噪声 disp('对含水印图像加高斯噪声PSNR'); myPSNR=func_PSNR(ImgWm,orig_image_show) figure(3); subplot(131) imshow(orig_image_show,[]) xlabel('原图像'); subplot(132) imshow(watermarked_image_int,[]); xlabel('嵌入水印后的图像') subplot(133) imshow(ImgWm,[]); xlabel('加高斯噪声后的图片') disp('对含水印图像加椒盐噪声'); ImgWm=imnoise(ImgWm,'salt & pepper', 0.001); %对含水印图像加椒盐噪声 disp('对含水印图像加椒盐噪声PSNR'); myPSNR=func_PSNR(ImgWm,orig_image_show) figure(4); subplot(131) imshow(orig_image_show,[]) xlabel('原图像'); subplot(132) imshow(watermarked_image_int,[]); xlabel('嵌入水印后的图像') subplot(133) imshow(ImgWm,[]); xlabel('加椒盐噪声后的图片')