dear sir i am doing project on watermarkimg using dct and dwt and i have a problem in extraction

this is where i am not getting any idea to do with plz help me out....

   imgWMrked=imread('lena.jpg');
           [LL11, HL11, LH11, HH11] = dwt2(imgWMrked, 'db1');

           lvl1 = [LL11, HL11;LH11, HH11];
            imshow(lvl1)
  %        figure(2), imshow(uint8(WTr_Im_L1));

           [LL22, HL22, LH22, HH22] = dwt2(HL11, 'db1');
           lvl2 = [LL22, HL22;LH22, HH22];
           lvl3 = [LL11,  lvl2; LH11, HH11];
           subplot(1,2,2), 
           imshow(uint8(lvl3)); 
           title('After DWT Image')

% Divide the sub-band HL22 (or HH22 ) into 4 x 4 blocks.

              [R C] = size(HL22);

              startR = 1;
              endR = R/4;
              for m = 1:4
                  startC = 1;
                  endC = C/4;
                  for n = 1:4
                      parts(m,n) = {HL22(startR:endR, startC:endC)};

                      startC = startC + (C/4);
                      endC = endC + (C/4);
                  end
                  startR = startR + (R/4);
                  endR = endR + (R/4);
              end

% Apply DCT to each block in the chosen sub-band (HL22).

              for m = 1:4
                  for n = 1:4
                      tempData = cell2mat(parts(m,n));
                      dctPartsWMarkd(m,n) = {dct2(tempData)};
                  end
              end

% Select and Re-formulate the grey-scale watermark image into a
% vector of zeros and ones.

              imgMarka = imread('peppers.png');

              if(~isgray(imgMarka))
                  imgMarka = rgb2gray(imgMarka);
                  imgMarkb = im2bw(imgMarka);

              end

   %Psuedorandom numbers generation
        key0=0.3;
        for i=1:200
        key0=2.925*key0*(1-key0);
        end
        key1=3.925;
        for i=1:1
          for j=1:2
            key0=key1*key0*(1-key0);
            a(i,j)=key0;
          end
       end
         key3=0.2;
         key2=3.925;
      for i=1:1
          for j=1:2
            key3=key2*key3*(1-key3);
            b(i,j)=key3;
          end
      end
           key16=0.3;
           key2=3.925;
      for i=1:1
          for j=1:2
             key16=key2*key16*(1-key16);
             c(i,j)=key16;
          end
      end
        t=0.16;
        w0=0.2;
        w1=0.5;
        w2=0.3;
        w=(1-t)^2*w0+2*t*(1-t)*w1+t^2*w2;
     for i=1:1
         for j=1:2  
           P(i,j)=(1-t)^2*a(i,j)*w0+2*t*(1-t)*b(i,j)*w1+t^2*c(i,j)*w2;
  %      d(i,j)=P(i,j)/w;
           d(i,j)=P(i,j);
         end
     end
    x=d;
    e1=round(x*255);
    pseudoSequence3=e1(1);
    pseudoSequence4=e1(2);

% Embed the two pseudorandom sequences, PN_0 and PN_1, with a gain factor
% alpha, in the DCT transformed 4x4 blocks of the selected DWT sub-bands of
% the host image.

%            extractedMark = imgMark;

            alpha = 0.05;
            markCount = 1;
              for m = 1:4
                  for n = 1:4
                      pseudoCount = 1;
                      tempDataWMarkd = cell2mat(dctPartsWMarkd(m,n));
                      tempDataHost = cell2mat(dctPartsHost(m,n));
                      for i = 29:226
                          ind = find(index == i);
                          diff1 = (tempDataHost(ind)) - ((tempDataWMarkd(ind)) - ((alpha * pseudoSequence3(pseudoCount))));
                          diff2 = (tempDataHost(ind)) - ((tempDataWMarkd(ind)) - ((alpha * pseudoSequence4(pseudoCount))));
                          if abs(diff1) < abs(diff2)
                              extractedMark(markCount) = 0;
                          else
                              extractedMark(markCount) = 1;
                          end
                          markCount = markCount + 1;
                      end
                      dctPartsWMarkd(m,n) = {tempDataWMarkd};
                  end
              end

         figure(7), 
         extractedMark1=imresize(extractedMark,[256 256]); 
         imshow(extractedMark1)
         title('Extracted WaterMark');
         imwrite(extractedMark, 'extractedMark.bmp');

[Walter Roberson]

It is not clear what difficulty you are having with extraction ?