Code for hiding a Larger black and white image in a smaller colour image

i have written a matlab code for hiding a larger black and white image in a smaller colour image by setting the the first bit of black and white image in lsb of r component , 2nd bit in lsb of g component and 3rd bit in lsb of b component of the colour image and so on. but only half the image is being recovered.how do i correct it?

   % read in the cover object you want to use for embedding
   file_name='ballon.png';
   cover_object=imread(file_name);
   cover_object=imresize(cover_object,[200 200]);
   cr=cover_object(:,:,1);
   cg=cover_object(:,:,2);
   cb=cover_object(:,:,3);

   % read the message image you want to hide in the cover image
   file_name='baboon.bmp';
   message=imread(file_name);
   message=imresize(message,[600 600]);

   % conversions needed to spread the image values on a 256 gray-scale
   message=double(message);
   message=round(message/256);
   figure(1),imshow(message),title('message');

   message=uint8(message);

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

   % set the LSB of cover_object(ii,jj) to the value of the MSB of watermark(ii,jj)
   wr=cr;
   wg=cg;
   wb=cb;
   i=1;
   j=1;
   for ii= 1:Mc
     for jj = 1:Nc

       wr(ii,jj)=bitset(wr(ii,jj),1,message(i,j));

       wg(ii,jj)=bitset(wg(ii,jj),1,message(i+1,j));

       wb(ii,jj)=bitset(wb(ii,jj),1,message(i+2,j));

       if j == Nm
        j=1;
        i=i+3;
       else
        j=j+1;
       end
     end
   end
   message_image=cat(3,wr,wg,wb);

   % write to file the image
   imwrite(message_image,'lsb_message.bmp','bmp');

   % display encoded image
   figure(2)
   imshow(message_image,[])
   title('encoded Image')

   //Decryption

   % read in encoded cover image
   file_name='lsb_message.bmp';
   message_image=imread(file_name);

   % determine size of encoded cover image
   Mw=size(message_image,1);  %Height
   Nw=size(message_image,2);  %Width

   enc=message_image;
   er=enc(:,:,1);
   eg=enc(:,:,2);
   eb=enc(:,:,3);

   % use lsb of encoded cover image to recover message
   for ii = 1:Mw
     for jj = 1:Nw
        msg(i,j)=bitget(er(ii,jj),1);
        msg(i+1,j)=bitget(eg(ii,jj),1);
        msg(i+2,j)=bitget(eb(ii,jj),1);
        if j == Nm
         j=1;
         i=i+3;
        else
         j=j+1;
        end

     end
   end

   % scale the recovered message image
   msg=256*double(msg);

   % scale and display recovered message image
   figure(1)
   imshow(msg)
   title('Recovered image');

Answer 1

[Image Analyst]

I'd guess by stepping through the code to see exactly what it's doing and where it might be going wrong. See http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/

[Image Analyst]

Attached is my demo of LSB watermarking.