wmarking.rar_watermark

%% Watermark Embedding algorithm function [watermarked_image, signature] = watermark_embedding(cover_image, watermark_logo, key, print_figures) % 1. Apply Haar wavelet and decompose cover image into four sub-bands: % LL, HL, LH, and HH [LL, HL, LH, HH] = dwt2(cover_image, 'haar'); % 2. Using Haar wavelet, further decompose LL band to the 4th level. % [LL_1, HL_1, LH_1, HH_1] = dwt2(LL, 'haar'); % 1st step DWT % [LL_2, HL_2, LH_2, HH_2] = dwt2(LL_1, 'haar'); % 2nd step DWT % [LL_3, HL_3, LH_3, HH_3] = dwt2(LL_2, 'haar'); % 3rd step DWT % [LL_4, HL_4, LH_4, HH_4] = dwt2(LL_3, 'haar'); % 4rth step DWT if (print_figures == true) % Images coding. cod_cA1 = wcodemat(LL); cod_cH1 = wcodemat(HL); cod_cV1 = wcodemat(LH); cod_cD1 = wcodemat(HH); dec2d = [cod_cA1, cod_cH1; cod_cV1, cod_cD1]; % Plot one step decomposition figure; image(dec2d); title('One step DWT decomposition'); clear('dec2d', 'cod_cA1', 'cod_cH1', 'cod_cV1', 'cod_cD1'); end % 3. Apply SVD to HH (high frequency) band [Uh Sh Vh] = svd(HH, 'econ'); % 4. Watermark logo W is decomposed using SVD [Uw Sw Vw] = svd(watermark_logo, 'econ'); % 5. Replace singular values of the HH (high frequency) band with the % singular values of the watermark Sh_diag = diag(Sh); Sw_diag = diag(Sw); % for ii = 1:size(Sw, 1) % Sh_diag(ii) = Sw_diag(ii); % end if (length(watermark_logo) >= 256) Sh_diag(1:length(Sh), :) = Sw_diag(1:length(Sh), :); elseif(length(watermark_logo) < 256) Sh_diag(1:length(watermark_logo), :) = Sw_diag(1:length(watermark_logo), :); end Sh(logical(eye(size(Sh)))) = Sh_diag; %----- Signature generation algorithm % 6. Generate signature signature = signature_generation(Uw, Vw, key); %---- Signature embedding algorithm % 7. Embedd signature to cover image % LL_inv = signature_embedding(LL_4, HH_4, signature); LL_inv = signature_embedding(LL, signature, print_figures); % 8. Apply SVD to obtain the modified HH band wich now holds the SV's of % watermark logo HH_modified = Uh * Sh * Vh'; % 9. Apply inverse DWT with modified LL(LL_inv) & HH(HH_modified) band to % obtain the watermarked image % Here the HH band should be the one modified with SV's watermarked_image = idwt2(LL_inv, HL, LH, HH_modified, 'haar'); if (print_figures == true) figure; subplot(2, 2, 1); imshow(cover_image, []); title('Cover image'); subplot(2, 2, 2); imshow(watermarked_image, []); title('Watermarked image signed with secret key'); subplot(2, 2, 3); imshow(watermark_logo, []); title('Watermark logo'); end clear('LL', 'HL', 'LH', 'HH',... 'LL_1', 'HL_1', 'LH_1', 'HH_1', ... 'LL_2', 'HL_2', 'LH_2', 'HH_2',... 'LL_3', 'HL_3', 'LH_3', 'HH_3',... 'LL_4', 'HL_4', 'LH_4', 'HH_4'); clear('Uh', 'Sh', 'Vh', 'Uw', 'Sw', 'Vw', 'Sh_diag', 'Sw_diag'); end