digital image watermarking. using DWT

I'm working in digital image watermarking. I've found DWT matlab code on internet, but it can't give proper results. plz debug it, so that it works properly.

% Watermark Embeding
clear all;
 % save start time
start_time=cputime;
 k=2;            % set the gain factor for embeding
 % read in the cover object
file_name='_lena_std_bw.bmp';
cover_object=double(imread(file_name));
 % determine size of watermarked image
Mc=size(cover_object,1);    %Height
Nc=size(cover_object,2);    %Width
 % read in the message image and reshape it into a vector
file_name='_copyright.bmp';
message=double(imread(file_name));
Mm=size(message,1);                         %Height
Nm=size(message,2);                         %Width
message_vector=round(reshape(message,Mm*Nm,1)./256);

[cA1,cH1,cV1,cD1] = dwt2(cover_object,'haar');
 % add pn sequences to H1 and V1 componants when message = 0 
for (kk=1:length(message_vector))
    pn_sequence_h=round(2*(rand(Mc/2,Nc/2)-0.5));
    pn_sequence_v=round(2*(rand(Mc/2,Nc/2)-0.5));
       if (message(kk) == 0)
        cH1=cH1+k*pn_sequence_h;
        cV1=cV1+k*pn_sequence_v;
    end
end
 % perform IDWT
watermarked_image = idwt2(cA1,cH1,cV1,cD1,'haar',[Mc,Nc]); 
 % convert back to uint8
watermarked_image_uint8=uint8(watermarked_image);
 % write watermarked Image to file
imwrite(watermarked_image_uint8,'dwt_watermarked.bmp','bmp');
 % display processing time
elapsed_time=cputime-start_time,
% display watermarked image
figure(1)
imshow(watermarked_image_uint8,[])
title('Watermarked Image')

% Watermark Recovery

clear all;

% save start time
start_time=cputime;

% read in the watermarked object
file_name='dwt_watermarked.bmp';
watermarked_image=double(imread(file_name));

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

% read in original watermark
file_name='_copyright.bmp';
orig_watermark=double(imread(file_name));

% determine size of original watermark
Mo=size(orig_watermark,1);  %Height
No=size(orig_watermark,2);  %Width
 % initalize message to all ones
message_vector=ones(1,Mo*No);
 [cA1,cH1,cV1,cD1] = dwt2(watermarked_image,'haar');
 % add pn sequences to H1 and V1 componants when message = 0 
for (kk=1:length(message_vector))
    pn_sequence_h=round(2*(rand(Mw/2,Nw/2)-0.5));
    pn_sequence_v=round(2*(rand(Mw/2,Nw/2)-0.5));
       correlation_h(kk)=corr2(cH1,pn_sequence_h);
    correlation_v(kk)=corr2(cV1,pn_sequence_v);
    correlation(kk)=(correlation_h(kk)+correlation_v(kk))/2;
end
 for (kk=1:length(message_vector))
    if (correlation(kk) > mean(correlation))
        message_vector(kk)=0;
    end
end
 % reshape the message vector and display recovered watermark.
figure(2)
message=reshape(message_vector,Mo,No);
imshow(message,[])
title('Recovered Watermark')
 % display processing time
elapsed_time=cputime-start_time,

[DAVID KING]

If u have any query thn regarding ur project either mail at [e-mail] or, https://www.facebook.com/MatlabProjects-909644652486619. Kindly Spread it to Help Others.

[meziane madani]

hi, what is exectly your problem ?

Answer 1

[Afroja Akter]

could u give any code for evalution purpose like NC(NORMALISED CORRELATION),,also could u tell me why not i could not save ma image wchich has been embedded,,

[Soujanya Dirisinam]

im aslo getting errors while running could you plz tell me tha correct code by taking an example image

[DAVID KING]

If u have any query thn regarding ur project either mail at [e-mail] or, https://www.facebook.com/MatlabProjects-909644652486619

Answer 2

[azz taha]

Error using reshape To RESHAPE the number of elements must not change.

Error in Untitled (line 17) message_vector=round(reshape(message,Mm*Nm,1)./256);

[Walter Roberson]

imread() returns 3 dimensional data for color images. You are extracting the rows and columns but neglecting the number of color planes.

Note: images are sometimes stored as color but look grey. Equal amounts of Red, Blue, and Green make different brightnesses of white.