%DWT水印源码
clear all;
% 保存开始时间
start_time=cputime;
k=20;
blocksize=8; % 设置块的大小
% 读入原图像
file_name='lena.bmp';
cover_object=double(imread(file_name));
cover_object1=double(imread(file_name));
% 原图像的行数与列数
Mc=size(cover_object,1); %原图像行数
Nc=size(cover_object,2); %原图像列数
% 最大嵌入信息量
max_message=Mc*Nc/(blocksize*2);
% 读入水印图像
file_name='c.bmp';
message=double(imread(file_name));
%%水印图像的行数与列数
Mm=size(message,1); %水印行数
Nm=size(message,2); %水印列数
message_vector=reshape(message,1,Mm*Nm);
% 检查水印信息是否过大
if (Mm*Nm> max_message)
error('水印太大')
end
%将随机数发生器的状态置为1100
randn('state',1100);
% 产生watermarked_image,并写入原图信息
watermarked_image=cover_object;
% 将图像分块嵌入
% 当 (2,2) > (2,3) 且 message_pad(kk)=0
% 当 (2,2) < (2,3) 且 message_pad(kk)=1
%%经过分析可以得出结论:在提取水印时,如果cD1(2,2)>cD1(2,3)便是嵌入了水印的黑色像素,
%%反之则是嵌入了白色像素
x=1;
y=1;
h=waitbar(0,'嵌入水印,请等待');
for (kk = 1:length(message_vector))
% 对块进行DWT变换
[cA1,cH1,cV1,cD1] = dwt2(cover_object(x:x+blocksize-1,y:y+blocksize-1),'haar');
a=cD1;
% 如果 message_pad(kk)== 0
if (message_vector(kk) == 0)
% 且(2,2) < (2,3) ,交换它们
if (cD1(2,2) < cD1(2,3))
temp=cD1(2,3);
cD1(2,3)=cD1(2,2);
cD1(2,2)=temp;
end
% 如果message_pad(kk) == 1,
elseif (message_vector(kk) == 1)
% 且(2,2) > (2,3) ,交换它们
if (cD1(2,2) >= cD1(2,3))
temp=cD1(2,3);
cD1(2,3)=cD1(2,2);
cD1(2,2)=temp;
end
end
% 检查(2,2) , (2,3)的差是否>= k
if cD1(2,2) > cD1(2,3)
if cD1(2,2) - cD1(2,3) < k
cD1(2,2)=cD1(2,2)+(k/2);
cD1(2,3)=cD1(2,3)-(k/2);
end
else
if cD1(2,3) - cD1(2,2) < k
cD1(2,3)=cD1(2,3)+(k/2);
cD1(2,2)=cD1(2,2)-(k/2);
end
end
%IDWT
watermarked_image(x:x+blocksize-1,y:y+blocksize-1)= idwt2(cA1,cH1,cV1,cD1,'haar',[Mc,Nc]);
% 移动到下一块
if (x+blocksize) >= Nc
x=1;
y=y+blocksize;
else
x=x+blocksize;
end
waitbar(kk/length(message_vector),h);
end
close(h);
% 转换为uint8并写入dwt_watermarked.bmp
watermarked_image_uint=uint8(watermarked_image);
imwrite(watermarked_image_uint,'dwt_watermarked.bmp','bmp');
% 显示运行时间
elapsed_time=cputime-start_time,
% 显示图像
figure(1)
imshow(message,[]);
title('水印');
figure(2)
subplot(1,2,1);
imshow(watermarked_image_uint,[])
title('嵌入水印图像')
subplot(1,2,2);
imshow(cover_object1,[]);
title('原图');
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