基于Arnold变换的DCT域数字图像水印算法研究(15)

[M_marked,N_marked]=size(watermarked_image); %计算水印的行数和列数 % figure(1); subplot(121);

imshow(watermarked_image); title('接受的嵌水印的载体图像'); cover_image=imread(file_name);

cover_image=imresize(cover_image,[512 512]); %改变水印图像的大小 cover_image=double(cover_image); %转换为双精度数组 watermarked_image=double(watermarked_image);

%PSNR=psnr(cover_image,watermarked_image), %计算受攻击后嵌入水印图像和原始载体图像的峰值信噪比PSNR %name1='嵌入水印后的载体图像';

%title(strcat(num2str(name1),' PSNR=',num2str(PSNR))); blocksize=8; k1=1/5; x=3; y=3;

p=M_marked/blocksize; q=N_marked/blocksize; key=0.001; randn('seed',key);

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西安文理学院本科毕业设计（论文）

A=randn(1,64*64); for n=1:64*64 if A(n)>=0 A(n)=1; else A(n)=0; end end

B=reshape(A,64,64); for j=1:p for i=1:q

dct_markedblock=dct2(watermarked_image((1+(j-1)*8):j*8,(1+(i-1)*8):i*8)); if k1*dct_markedblock(x,y)>0 wm_image(j,i)=1;

wm_image(j,i)=xor(wm_image(j,i),B(j,i)); else

wm_image(j,i)=0;

wm_image(j,i)=xor(wm_image(j,i),B(j,i)); end end end % figure;

% imshow(wm_image); % title('恢复的置乱水印图像');

%%%%%%%%对提取的信息进行Arnold变换恢复水印信息 %%%%%%%%%% wm_image=double(wm_image); tempImg=wm_image; x1=8;

for n=1:(48-x1)% 置乱次数 for u=1:p for v=1:q

temp=tempImg(u,v); ax=mod((u-1)+(v-1),p)+1; ay=mod((u-1)+2*(v-1),q)+1; outImg(ax,ay)=temp; end

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西安文理学院本科毕业设计（论文）

end

tempImg=outImg; end

wm_image=tempImg;

wm_image1=double(wm_image); % 显示运行时间

elapsed_time=cputime-start_time;

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