Image Watermark using Wavelet level 2

2. Watermark algorithm
• function [D]=blockdwt2c(A,W);
•
• [row,col]=size(A);
•
• Tr=250;
• k=0.01;
•
• [ca,ch,cv,cd] = dwt2(A,'Haar');
• c1 = [ch cv cd];
•
• %%%%%%Wavelet level 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
•
• [ca1, ch1, cv1, cd1]= dwt2(ca,'Haar');
•
• c2=[ch1 cv1 cd1];
•
• [h, w] = size(ca1');
• [m, n] = size(c2');
•
• W=dmgb(W,A);
•
• %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Here we take the wavelet transform of the
• %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%watermark

3. Watermark algorithm
•
•
continued
[caa chh cvv cdd]=dwt2(W,'Haar');
• W=caa;
• size(W);
•
• % Adding watermark image.
•
• for i=1:h
• for j=1:w
• if ca1(i,j)>Tr
• Ca(i,j)=ca1(i,j)+k*W(i,j); % <--------k*abs(double(c1(i,j)))*W(i,j); de olabilir
• else
• Ca(i,j)=ca1(i,j);
• end
• end
• end
•
• % CH1=C1(1:h,1:w);
• % CV1=C1(1:h,w+1:2*w);
• % CD1=C1(1:h,2*w+1:3*w);
•
• D0= double( idwt2(Ca,ch1, cv1, cd1,'Haar') );
•
• D= double(idwt2(D0, ch, cv, cd, 'Haar'));

4. Reversing and detecting
the watermark
• h = fspecial('gaussian');
• >> I2 = imfilter(marked,h);
• imshow(uint8(marked)),
title('Original Image')
• figure, imshow(uint8(I2)),
title('Filtered Image')
• >> a=I2-image1;
• >> [ca ch cv
cd]=dwt2(a,'haar');
• >> [ca1 ch1 cv1 cd1]=
dwt2(ca,'haar');
• >> imshow(ca1)