数字水印图像的嵌入与提取源代码

clear all; close all; clc;

M=256;%原图像长度

N=64; %水印长度

[filename1,pathname]=uigetfile('*.*','select the image');

image1=imread(num2str(filename1));

subplot(2,2,1);

imshow(image1); title('原图'); % orginal image for watermarking image1=double(image1);

imagew=imread('shuiyin.bmp');

imagew=im2bw(imagew,0.5);

subplot(2,2,2);imshow(imagew);title('原水印'); %original watermark

%嵌入水印

[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

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);colormap(gray(256));image(markedimage);title('含水印图');

imwrite(markedimage,gray(256),'watermarked.bmp','bmp');

%提取水印

image1=imread(num2str(filename1));image1=double(image1);

imaged=imread('watermarked.bmp');

[ca,ch,cv,cd] = dwt2(image1,'db1');

[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);

colormap(gray(256));image(W);title('从含水印图像中提取的水印'); imwrite(W,gray(256),'提取的水印.bmp','bmp');