A Semi-blind Watermarking Based on Discrete Wavelet Transform Authors: Chin-Chen Chang, Yung-Chen Chou, and Tzu-Chuen Lu Speaker: Yung-Chen Chou Date: Dec. 12, 2007

Introduction Invisible Visible Yung-Chen Chou

Introduction (Cont.) Framework of invisible watermark Embedding algorithm Yung-Chen Chou Detecting algorithm

Haar Wavelet Transform Introduction (Cont.) Haar Wavelet Transform Phase 1) Horizontal : L H a b c d e f g h i j k l m n o p A B C D E F G H I J K L M N O P A+B C+D A-B C-D E+F G+H E-F G-H I+J K+L I-J K-L M+N O+P M-N O-P Phase 2) Vertical : HH HL LH LL a b c d e f g h i j k l m n o p L H a+e b+f c+g d+h i+m j+n k+o l+p a-e b-f c-g d-h i-m j-n k-o l-p Yung-Chen Chou

The Proposed Method Image X X’ X* Watermark W W’ W* Codebook training Permute DWT Codebook Image X X’ X* Encode coefficients Index table Permute DWT Watermark W W’ W* Yung-Chen Chou Trusted Authenticated Center

The Proposed Method (Cont.) 71, 114, 97, 101 114, 115, 101, 124 71 114 115 180 97 101 124 86 53 128 119 116 146 127 129 115, 180, 124, 86 97, 101, 53, 128 101, 124, 128, 119 124, 86, 119, 116 53, 128, 146, 127 X* Normalized LL2 coefficients of X* 128, 119, 127, 129 119, 116, 129, 86 Training pool Codebook training (LBG) 96, 108, 109, 106 53, 128, 146, 127 115, 180, 124, 86 97, 101, 53, 128 Trained codebook 1 2 3 Yung-Chen Chou

The Proposed Method (Cont.) 31 198 186 124 146 211 140 104 119 126 180 100 156 86 1 2 3 96, 108, 109, 106 53, 128, 146, 127 115, 180, 124, 86 97, 101, 53, 128 Trained codebook Normalized LL2 coefficients of W* W* 2 1 Index table Yung-Chen Chou

The Proposed Method (Cont.) Watermark extracting Codebook training Permute DWT Codebook Image V V’ V* 2 1 Index table DWT IDWT Permute Trusted Authenticated Center W’ W* W** Yung-Chen Chou Watermark We

Experimental Results Yung-Chen Chou Table 2. The visual quality of the extracted watermark by using the proposed method (size of sliding window =22) Watermarks Host images Baboon Barbara Goldhill Lena Sailboat Zelda - 28.3201 29.5233 29.7928 26.6956 31.5927 31.7595 29.5151 29.7909 26.6945 31.594 31.7169 28.2465 29.7161 26.6629 31.5657 31.7539 28.3174 29.4524 26.6894 31.581 31.7612 28.3178 29.5197 29.791 31.5928 31.7696 28.319 29.5265 29.7922 26.696 Yung-Chen Chou

Experimental Results (Cont.)

Experimental Results (Cont.)

Conclusions The proposed method provides a greater control in terms of the robustness of the watermark. Yung-Chen Chou