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多媒體網路安全實驗室 Reversible Data Hiding with Improved Histogram Alteration Method Source:International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIHMSP),2010 Sixth. Authors:Hsiang-Cheh Huang, Yueh-Hong Chen, and I-Hung Wang Speaker:Cheng Hsu Date:2011/05/05 多媒體網路安全實驗室 Outline 1. Introduction 2. Related work 3. Proposed scheme 4. Experimental results 5. Conclusions 2 多媒體網路安全實驗室 1. Introduction Reversible data hiding: 1. Histogram-based scheme. 2. Difference expansion (DE) scheme. They consider the easily implemented algorithm, called histogram-based scheme in reversible data hiding, and they modify the difference between adjacent pixels for making data hiding possible. 3 多媒體網路安全實驗室 2. Related work Embedding procedure 154 156 154 154 157 154 shift 157 153 155 158 153 156 152 155 154 152 156 154 Original image Cover image 8 7 6 5 4 Peak point 3 2 1 0 Zero point 152 153 154 155 156 157 158 Cover Original image histogram histogram 4 多媒體網路安全實驗室 154 157 154 155 155 157 154 S=110 158 153 156 P’= P + 1 158 153 156 152 156 154 P’= P 152 156 154 Cover image Stego image 8 7 6 5 4 If S=0 embedded in 154 If S=1 embedded in 155 3 2 1 0 152 153 154 155 156 157 Cover image histogram Stego 5 158 多媒體網路安全實驗室 Extracted procedure 155 157 155 P = P’ - 1 S= 1 158 153 156 P = P’ - 1 S= 1 152 156 154 P = P’ S= 0 Stego image 154 155 156 157 154 155 157 158 153 155 156 152 155 156 154 Cover image Original image 8 7 6 5 4 S= 110 3 2 1 0 152 153 154 155 156 157 Cover image histogram 6 158 多媒體網路安全實驗室 3. Proposed scheme Embedding procedure 198 199 202 200 Difference： 200 201 di pi 1 pi , 1 i M N 1 203 204 d1 p11 p1 199 198 1 198 199 200 202 200 201 d 2 p21 p2 200 199 1 Original image Peak point 3 2 Zero point 1 0 -2 -1 0 1 2 3 4 Original difference histogram 7 204 203 多媒體網路安全實驗室 198 199 d=1 202 200 d=1 200 201 203 204 S=1 0 If S = 1 d’ = d - 1 If S = 0 d’ = d Original image If S=1 embedded in 0 Inverse S-type scan 203 204 200 201 201 202 200 204 198 198 198 198 202 200 200 203 If S=0 embedded in 1 3 2 1 0 -2 -1 0 1 2 3 4 Original difference histogram Stego image 8 多媒體網路安全實驗室 Extraction procedure 203 204 200 201 202 198 Inverse S-type scan 198 198 199 If d’ = 0 202 200 200 d = d’ + 1 200 200 201 198 203 204 Original image Stego image S=1 P = p’ + d = 198 + 1 = 199 If d’ = 1 d = d’ S=0 3 P = p’ + d = 200 + 0 = 200 2 1 -2 -1 0 1 2 3 4 Stego image difference histogram 9 多媒體網路安全實驗室 4. Experimental results The image quality and the number of modified blocks under a fixed number of capacity. 10 多媒體網路安全實驗室 Comparisons between maximal capacity and that in [2]. 11 多媒體網路安全實驗室 5. Conclusions In this paper, they proposed an improved reversible data hiding scheme by modifying the histogram of original image with its inherent characteristics. In comparison with conventional scheme [2], more capacity with their scheme can be embedded. 12 多媒體網路安全實驗室