基于小波变换的数字水印嵌入与提取_matlab代码

clc; clear all; close all; N=64; %水印长度 image1=imread('pic.jpg'); subplot(2,2,1);imshow(image1); title('原图像'); image1=double(image1); %水印图像 imagew=imread('watermark1.jpg'); thresh = graythresh(imagew); %自动确定二值化阈值 imagew=im2bw(imagew,0.5); subplot(2,2,2);imshow(imagew);title('水印图像'); %嵌入水印 %小波变换 [ca,ch,cv,cd] = dwt2(image1,'db1'); [cas,chs,cvs,cds] = dwt2(ca,'db1'); for i=1:N for j=1:N if imagew(i,j)==0 a=-1; else a=1; end Ca(i,j)=cas(i,j)*(1+a*0.03); end end %小波逆变换 IM= idwt2(Ca,chs,cvs,cds,'db1') ; markedimage=double(idwt2(IM,ch,cv,cd,'db1')); %显示嵌入后水印图像 subplot(2,2,3);imshow(markedimage,[]);title('marked image'); imwrite(markedimage,gray(256),'pic_加水印后的图像.bmp','bmp'); %% %提取水印 image1=double(image1); imaged=markedimage; [ca,ch,cv,cd] = dwt2(image1,'db1'); %小波变换 [cas,chs,cvs,cds]=dwt2(ca,'db1'); [caa,chh,cvv,cdd]=dwt2(imaged,'db1'); [caas,chhs,cvvs,cdds]=dwt2(caa,'db1'); for p=1:N for q=1:N a=caas(p,q)/cas(p,q)-1; if a<0 W(p,q)=0; else W(p,q)=255; end end end %显示提取的水印 subplot(2,2,4);imshow(W,[]);title('从含水印图像中提取的水印'); imwrite(W,'watermark_从含水印图像中提取的水印.bmp');