DCT数字水印matlab实现参考源代码

M=256; %原图256x256 N=32; %水印32x32同时,256/8=32 K=8; %8x8的分块 I=zeros(M,M); J=zeros(N,N); BLOCK=zeros(K,K); subplot(2,2,1); I=imread('original.jpg'); imshow(I); title('原图'); subplot(2,2,2); J=imread('waterPrint.bmp'); imshow(J); title('水印'); %%%%%%% 分块,DCT变换 %%%%%%% for p=1:N %256/8 for q=1:N x=(p-1)*K+1; %每个小块左上角的点 y=(q-1)*K+1; BLOCK=I(x:x+K-1,y:y+K-1); %取每个小块相应元素保存到BLOCK BLOCK=dct2(BLOCK); %二维离散余弦变换 %% 嵌入水印,反DCT变换 if J(p,q)==0 a=-1; else a=1; end BLOCK=BLOCK*(1+a*0.03); BLOCK=idct2(BLOCK); %反二维离散余弦变换 I(x:x+K-1,y:y+K-1)=BLOCK; end end subplot(2,2,3); imshow(I); title('嵌入水印后的图像'); imwrite(I,'waterMarked.jpg'); %%%%% 提取水印 %%%%% I=imread('original.jpg'); %原图 P=imread('waterMarked.jpg'); %嵌入水印的图像 %提取水印算法 for p=1:N for q=1:N x=(p-1)*K+1; y=(q-1)*K+1; BLOCK1=I(x:x+K-1,y:y+K-1); BLOCK1=idct2(BLOCK1); BLOCK2=P(x:x+K-1,y:y+K-1); BLOCK2=idct2(BLOCK2); a=BLOCK2(1,1)/BLOCK1(1,1)-1; if a<0 W(p,q)=0; else W(p,q)=1; end end end subplot(2,2,4); imshow(W); title('提取的水印'); imwrite(W,'waterPrint2.bmp');