how to get the same image after extract watermark

 clear all; 

 % read in the cover object you want to use for embedding
 file_name='lena512.bmp';
 cover_object=imread(file_name);

 % read the message image you want to hide in the cover image
 file_name='watermark.jpg';
 message=imread(file_name);

 % determine the size of cover image used for embedding
 Mc=size(cover_object,1);  %Height
 Nc=size(cover_object,2);  %Width

 % determine the size of message object to embed
 Mm=size(message,1);          %Height
 Nm=size(message,2);          %Width

 %y = uint8(wgn(Mm,Nm,1));

 % title the message object out to cover object size to generate watermark
 for ii = 1:Mc
    for jj = 1:Nc
        watermark(ii,jj)=message(mod(ii,Mm)+1,mod(jj,Nm)+1);
    end
 end

 % set the LSB of cover_object(ii,jj) to the value of the MSB of watermark(ii,jj)
 watermarked_image=cover_object;
for ii = 1:Mc
    for jj = 1:Nc
        watermarked_image(ii,jj)=bitset(watermarked_image(ii,jj),1,watermark(ii,jj));
    end
end

 % write to file the two images
 imwrite(watermarked_image,'lsb_watermarked.bmp');
 figure(1)
 imshow(watermarked_image,[])
 title('Watermarked Image')

extarct code

 clear all;

 % read in watermarked image
 file_name='lsb_watermarked.bmp';
 watermarked_image=imread(file_name);

 % determine size of watermarked image
 Mw=size(watermarked_image,1);  %Height
 Nw=size(watermarked_image,2);  %Width

 % use lsb of watermarked image to recover watermark
 for ii = 1:Mw
    for jj = 1:Nw
        watermark(ii,jj)=bitget(watermarked_image(ii,jj),1);
    end
 end

 % scale the recovered watermark
 watermark=(256*double(watermark));

 % scale and display recovered watermark
 figure(1)
 imshow(watermark,[])
 title('Recovered Watermark')

the ortiginal watermark image

watermark after extract

how i fix this?

[Rizwan Taj]

No body answered this question ?