Re: invisible watermarking

"Maulana Wahid" <maulanawahid13@yahoo.com> wrote in message <lbv9sj$4pr$1@newscl01ah.mathworks.com>...
> "mohammad " <rocky_halo@hotmail.com> wrote in message <ht0r4l$6b0$1@fred.mathworks.com>...
> > %Name: Chris Shoemaker
> > %Course: EER-280 - Digital Watermarking
> > %Project: Block DCT Based method, using comparision between mid-band coeffcients
> > % Watermark Embeding
> >
> > clear all;
> >
> > % save start time
> > start_time=cputime;
> >
> > k=50; % set minimum coeff difference
> > blocksize=8; % set the size of the block in cover to be used for each bit in watermark
> >
> > % read in the cover object
> > file_name='_lena_std_bw.bmp';
> > cover_object=double(imread(file_name));
>
> where did you get this source code?
> >
> > % determine size of cover image
> > Mc=size(cover_object,1); %Height
> > Nc=size(cover_object,2); %Width
> >
> > % determine maximum message size based on cover object, and blocksize
> > max_message=Mc*Nc/(blocksize^2);
> >
> > % read in the message image
> > file_name='_copyright.bmp';
> > message=double(imread(file_name));
> > Mm=size(message,1); %Height
> > Nm=size(message,2); %Width
> >
> > % reshape the message to a vector
> > message=round(reshape(message,Mm*Nm,1)./256);
> >
> > % check that the message isn't too large for cover
> > if (length(message) > max_message)
> > error('Message too large to fit in Cover Object')
> > end
> >
> > % pad the message out to the maximum message size with ones
> > message_pad=ones(1,max_message);
> > message_pad(1:length(message))=message;
> >
> > % generate shell of watermarked image
> > watermarked_image=cover_object;
> >
> > % process the image in blocks
> > % encodes such that (5,2) > (4,3) when message(kk)=0
> > % and that (5,2) < (4,3) when message(kk)=1
> > x=1;
> > y=1;
> > for (kk = 1:length(message_pad))
> >
> > % transform block using DCT
> > dct_block=dct2(cover_object(y:y+blocksize-1,x:x+blocksize-1));
> >
> > % if message bit is black, (5,2) > (4,3)
> > if (message_pad(kk) == 0)
> >
> > % if (5,2) < (4,3) then we need to swap them
> > if (dct_block(5,2) < dct_block(4,3))
> > temp=dct_block(4,3);
> > dct_block(4,3)=dct_block(5,2);
> > dct_block(5,2)=temp;
> > end
> >
> > % if message bit is white, (5,2) < (4,3)
> > elseif (message_pad(kk) == 1)
> >
> > % if (5,2) > (4,3) then we need to swap them
> > if (dct_block(5,2) >= dct_block(4,3))
> > temp=dct_block(4,3);
> > dct_block(4,3)=dct_block(5,2);
> > dct_block(5,2)=temp;
> > end
> > end
> >
> > % now we adjust the two values such that their difference >= k
> > if dct_block(5,2) > dct_block(4,3)
> > if dct_block(5,2) - dct_block(4,3) < k
> > dct_block(5,2)=dct_block(5,2)+(k/2);
> > dct_block(4,3)=dct_block(4,3)-(k/2);
> > end
> > else
> > if dct_block(4,3) - dct_block(5,2) < k
> > dct_block(4,3)=dct_block(4,3)+(k/2);
> > dct_block(5,2)=dct_block(5,2)-(k/2);
> > end
> > end
> >
> > % transform block back into spatial domain
> > watermarked_image(y:y+blocksize-1,x:x+blocksize-1)=idct2(dct_block);
> >
> > % move on to next block. At and of row move to next row
> > if (x+blocksize) >= Nc
> > x=1;
> > y=y+blocksize;
> > else
> > x=x+blocksize;
> > end
> > end
> >
> > % convert to uint8 and write the watermarked image out to a file
> > watermarked_image_int=uint8(watermarked_image);
> > imwrite(watermarked_image_int,'dct1_watermarked.bmp','bmp');
> >
> > % display processing time
> > elapsed_time=cputime-start_time,
> >
> > % display psnr of watermarked image
> > psnr=psnr(cover_object,watermarked_image,Nc,Mc),
> >
> > % display watermarked image
> > figure(1);
> > imshow(watermarked_image,[])
> > title('Watermarked Image')
> >
> >
> >
> >
> >
> > this is the code ,i tried searching author but no luck...