dct_2.m

基于matlab编写的dct数字水印程序

size=256;
block=8;
blockno=size/block;
LENGTH=size*size/64;
Alpha1=0.02;
Alpha2=0.1;
T1=3;
I=zeros(size,size);
%D=zeros(size,size); 
BW=zeros(size,size); 
block_dct1=zeros(block,block);
%产生高斯水印，并显示水印信息；
randn('seed',10);
mark=randn(1,LENGTH);
subplot(2,2,1);
plot(mark);
title('watermarc:Gaussian noise');

%显示原图
subplot(2,2,2);I=imread('1.bmp','bmp');    
imshow(I);title('origine image');
II=rgb2gray(I);
%显示prewitt为算子的边缘图
BW=edge(II,'prewitt');
subplot(2,2,3);
imshow(BW);
title('edge of origine image');
%嵌入水印
k=1;
for m=1:64
   for n=1:64
      x=(m-1)*block+1;
      y=(n-1)*block+1;
      block_dct1=II(x:x+block-1,y:y+block-1);
      block_dct1=dct2(block_dct1);
      BW_8_8=BW(x:x+block-1,y:y+block-1);
      if m<=1|n<=1
         T=0;
      else
         T=sum(BW_8_8);    T=sum(T);
      end
      if T>T1
         Alpha=Alpha2;
      else
         Alpha=Alpha1;
      end
      %block_dct1(1,1)=block_dct1(1,1)*(1+Alpha*mark(k));
      block_dct1=idct2(block_dct1);
      D(x:x+block-1,y:y+block-1)=block_dct1;  
      k=k+1;

   end
end
%显示嵌入水印后的图像
subplot(2,2,4);imshow(D,[]);title('embeded image');