1. 多媒體網路安全實驗室 Source:International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIH- MSP),2010 Sixth. Authors:Hsiang-Cheh Huang, Yueh-Hong Chen, and I-Hung Wang Speaker:Cheng Hsu Date:2011/05/05 Reversible Data Hiding with Improved Histogram Alteration Method

2. 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

3. 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

4. 多媒體網路安全實驗室 4 2. Related work Original histogram Peak point Zero point 154155152 155153157 154156154 Original image 154156152 156153158 154157154 Cover image shift Cover image histogram 0 152153154155156157158 1 2 3 4 5 6 7 8 Embedding procedure

5. 多媒體網路安全實驗室 5 Cover image histogram S = 1 1 0 P’= P + 1 P’= P If S=1 embedded in 155If S=0 embedded in 154 154156152 156153158 154157154 Cover image Stego image histogram 0 152153154155156157158 1 2 3 4 5 6 7 8 156152 156153158 157155 Stego image 154 155 154

6. 多媒體網路安全實驗室 6 Cover image histogram 154156152 156153158 155157155 Stego image Extracted procedure S = 1 P = P’ - 1 S = 1 P = P’ - 1 P = P’ S = 0 S = 1 1 0 154156152 156153158 155157155 Cover image 154 156157155 Original image 0 152153154155156157158 1 2 3 4 5 6 7 8

7. 多媒體網路安全實驗室 7 3. Proposed scheme Difference ： 198199 202200 201 203204 198199200202200201204203 Peak point Zero point 0 1 2 3 10234-2 Original difference histogram Original image Embedding procedure

8. 多媒體網路安全實驗室 8 If S=0 embedded in 1 If S=1 embedded in 0 S = 1 0 If S = 1 d’ = d - 1 If S = 0 d’ = d 1 2 3 10234-2 Original difference histogram 204203 201200 202 199198 Original image 198 202200 201 203204 200 0 198 200202 201200 204203 Inverse S-type scan Stego image d = 1

9. 多媒體網路安全實驗室 9 203204 200201 202200 198 Stego image Extraction procedure Inverse S-type scan 204203 201200 202 198 1 2 3 10234-2 Stego image difference histogram If d’ = 0 d = d’ + 1 S = 1 If d’ = 1 d = d’ S = 0 199200 Original image P = p’ + d = 198 + 1 = 199 P = p’ + d = 200 + 0 = 200

10. 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

11. 多媒體網路安全實驗室 Comparisons between maximal capacity and that in [2]. 11

12. 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

13. 多媒體網路安全實驗室