Watermark Embedding Process
1. Apply RDWT (Redundant DWT) to original image
2.Apply SVD to the LL sub-band of Original image
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3.Apply RDWT to the watermark image.
4.Apply SVD to the LL Sub-band of watermark image
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5.Modify the singular values of the original image with the singular values of the watermark image
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6.Apply inverse SVD on the transformed original image with modified singular values.
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7.Apply inverse RDWT to obtain the watermarked image.
Watermark Extraction Process
1.Apply RDWT on the watermarked image.
2.Apply SVD to the LL sub-band of the watermarked image.
3.Extract the singular values of watermark image from the singular values of watermarked image and original image.
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4.Apply inverse SVD
5.Apply inverse RDWT to obtain the watermark image.
Matlab code is given below
Embedding
clc
clear all
close all
warning off
alpha = 0.25;
input_img = imread('lena512.bmp'); % read input image
[LL,LH,HL,HH] = dwt2(input_img,'haar','mode','sym'); % applying redundant DWT
[I_u,I_s,I_v] = svd(LL); % extract sigular values...
water_img = imread('cameraman.bmp'); % read watermark image
[WLL,WLH,WHL,WHH] = dwt2(water_img,'haar','mode','sym'); % applying redundant DWT
[W_u,W_s,W_v] = svd(WLL); % extract sigular values...
S_n = I_s + (alpha*W_s); %Watermark Embedding
new_LL = I_u*S_n*I_v'; %Watermarked Image Construction
new_img = idwt2(new_LL,LH,HL,HH,'haar','mode','sym');
new_img=uint8(new_img);
imwrite(new_img,'Watermarked.bmp');
Extraction
clc
clear all
close all
warning off
alpha = 0.25;
water_img = imread('Watermarked.bmp'); % read watermarked image
[WMLL,WMLH,WMHL,WMHH] = dwt2(water_img,'haar','mode','sym'); % applying redundant DWT
[Wm_u,Wm_s,Wm_v] = svd(WMLL); % extract sigular values...
input_img = imread('lena512.bmp'); % read input image
[LL,LH,HL,HH] = dwt2(input_img,'haar','mode','sym'); % applying redundant DWT
[I_u,I_s,I_v] = svd(LL); % extract sigular values...
S_w= (Wm_s-I_s)/alpha; % Watermark extraction
watermark=imread('cameraman.bmp');
[WLL,WLH,WHL,WHH] = dwt2(watermark,'haar','mode','sym'); % applying redundant DWT
[W_u,W_s,W_v] = svd(WLL); % extract sigular values...
new_WLL=W_u*S_w*W_v';
Watermark_img=idwt2(new_WLL,WLH,WHL,WHH,'haar','mode','sym');
Watermark_img=uint8(Watermark_img);
imwrite(Watermark_img, 'Watermark_img.bmp');
Related Search: Watermarking matlab code , Digital Watermarking RDWT matlab code ,SVD based Watermarking matlab code.Matlab watermark embedding and extraction.