clear all; 
%讀入載體圖像 
cover_image=imread('yt.bmp'); 
%讀入水印圖像 
water_image=imread('sy.bmp');
%water_image=rgb2gray(I);
%imwrite(water_image,'sy2.bmp');
water=double(water_image); 
water=round(water./256);%轉換為0，1組成的矩陣 
water=uint8(water);%轉換為uint8數 
imwrite(water,'sy3.bmp');
%確定載體圖像大小 
mc=size(cover_image,1) 
nc=size(cover_image,2) 
%確定水印圖像大小 
mm=size(water,1) %返回矩陣water的行數
nm=size(water,2) %返回矩陣water的列數
for i=1:mc 
    for j=1:nc 
        watermark(i,j)=water(mod(i,mm)+1,mod(j,nm)+1);
    end 
end  
watermarked_image1=cover_image; 
for i=1:mc 
    for j=1:nc 
        watermarked_image2(i,j)=bitset(watermarked_image1(i,j),1,watermark(i,j)); %在原圖像“watermarked_image1”的第一位嵌入水印“watermark(i,j)”
        a(i,j)=bitset(watermarked_image1(i,j),2,watermark(i,j));
        b(i,j)=bitset(watermarked_image1(i,j),3,watermark(i,j));
        c(i,j)=bitset(watermarked_image1(i,j),4,watermark(i,j));
        d(i,j)=bitset(watermarked_image1(i,j),5,watermark(i,j));
        e(i,j)=bitset(watermarked_image1(i,j),6,watermark(i,j));
        f(i,j)=bitset(watermarked_image1(i,j),7,watermark(i,j));
        g(i,j)=bitset(watermarked_image1(i,j),8,watermark(i,j));
    end  
end 
imwrite(watermarked_image2,'lsb_watermarked.bmp','bmp'); 
%---------顯示原水印圖像---------
%figure(1) 
%subplot(1,3,1); 
%imshow(water_image);
%title('原水印')
%xlabel('256*256');
%------------顯示載體圖像-------
%subplot(1,3,2); 
%imshow(cover_image);
%title('載體圖像')
%xlabel('512*512');
%---------在最低位嵌入水印后的圖像顯示------------
%subplot(1,3,3); 
%imshow(watermarked_image2,[]); 
%title('在最低為平面嵌入水印后')
%xlabel('512*512');

figure(2),
subplot(1,4,1); 
imhist(water_image);
title('原水印')
xlabel('              直方圖1');
subplot(1,4,2);
imhist(cover_image );
title('嵌水印前載體')
xlabel(' 直方圖2');
subplot(1,4,3);
imhist(watermarked_image2);
title('1位平面嵌水印后')
xlabel(' 直方圖3');
subplot(1,4,4);
imhist(g);
title('8位平面嵌水印后')
xlabel(' 直方圖4');

%-------------水印依次從低到高位嵌入后的圖像顯示----------
figure(3)
subplot(2,4,1); 
imshow( watermarked_image2); 
title('1位平面嵌水印')
subplot(2,4,2); 
imshow(a); 
title('2位平面嵌水印')
subplot(2,4,3); 
imshow(b); 
title('3位平面嵌水印')
subplot(2,4,4); 
imshow(c); 
title('4位平面嵌水印')
subplot(2,4,5); 
imshow(d); 
title('5位平面嵌水印')
subplot(2,4,6); 
imshow(e); 
title('6位平面嵌水印')
subplot(2,4,7); 
imshow(f); 
title('7位平面嵌水印')
subplot(2,4,8); 
imshow(g); 
title('8位平面嵌水印')