How to detect watermarking in DWT~ Include matlab source~ please help me~~

how to detect watermarking??

I don't know how about detecting watermarking code

please help me!

I successed insert watermarking but I can't exctract watermark

clear all;
clc
% read gray image
gray_img  = imread('body_1_gray256.jpg');
% convert double image 
gray_img  = double(gray_img);
init = 0.0001; % 

% 
[p q] = size(gray_img);

% 
sign_img = imread('sign_image.jpg');

[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('haar');

[cA,cH,cV,cD] = dwt2(gray_img,Lo_D,Hi_D);    

% watermarking start
y = [cA cH;cV cD];
Y = y + init*abs(y).* double(sign_img); 
p=p/2;q=q/2;
for i=1:p
    for j=1:q

          ncA(i,j) = Y(i,j);      
          ncV(i,j) = Y(i+p,j);   
          ncH(i,j) = Y(i,j+q);   
          ncD(i,j) = Y(i+p,j+q);  
      end
  end

Watermarked_img = idwt2(ncA,ncH,ncV,ncD,Lo_R,Hi_R);

Answer 1

[B.k Sumedha]

clc
close all

%host

rgbimage=imread('host.jpg');
figure;imshow(rgbimage);title('original color image');
[h_LL,h_LH,h_HL,h_HH]=dwt2(rgbimage,'haar');
dec2d = [... 
        h_LL,     h_LH;     ... 
        h_HL,     h_HH      ... 
        ];
figure,imshow(uint8(dec2d));title('DWT2 of original color image');

%watermark

rgbimage=imread('watermark.jpg');
figure;imshow(rgbimage);title('Watermark image');
[w_LL,w_LH,w_HL,w_HH]=dwt2(rgbimage,'haar');
dec2d = [... 
        w_LL,     w_LH;     ... 
        w_HL,     w_HH      ... 
        ];
figure,imshow(uint8(dec2d));title('DWT2 of Watermark image');

%watermarked

rgbimage=imread('watermarked.jpg');
figure;imshow(rgbimage);title('Watermarked image');
[wm_LL,wm_LH,wm_HL,wm_HH]=dwt2(rgbimage,'haar');
dec2d = [... 
        wm_LL,     wm_LH;     ... 
        wm_HL,     wm_HH      ... 
        ];
figure,imshow(uint8(dec2d));title('DWT2 of Watermarked image');

%watermarking

newwatermark_LL= (wm_LL-h_LL)/0.30;

%extracted watermark image

rgb2=idwt2(newwatermark_LL,w_LH,w_HL,w_HH,'haar');
figure;imshow(uint8(rgb2));title('Extracted watermark');
imwrite(uint8(rgb2),'EWatermark.jpg');

[DoSeok Lee]

Hi~ B.k Sumedha thank you for my Question But I wonder your matlab source~

%host rgbimage=imread('host.jpg');%<-- example cameraman.tif (my file name)256x256

%watermark rgbimage=imread('watermark.jpg'); %<-- exmaple rice.tif (my file name)256x256

%watermarked rgbimage=imread('watermarked.jpg'); <-- I don't know what image insert?