I don't know this watermarking code~ please explain code~

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');

-----------------------------------------------------------------

someone sent this watermarking sourece to me

but I don't understand this code~

I wonder these part matlab source~

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

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

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

Answer 1

[Thorsten]

You can download the full example from http://www.mathworks.com/matlabcentral/fileexchange/45051-color-dwt-image-watermarking

You first create the Watermarked.jpg using embedd.m and then you can can extract the image using extract.m, as far as I can see.

Answer 2

[B.k Sumedha]

I apologize for not replying to your previous query.

Its just that after this :

figure,imshow(uint8(dec2d));title('DWT2 of Watermarked image');

write this line.

imwrite(uint8(rgb2),'Watermarked.jpg');

This is where you will be saving the watermarked image. After this u will be using it to extract the image.