1. Reversible Date Hiding Based on Histogram Modification of pixel Differences IEEE Transactions on circuits and systems for video technology, VOL. 19, NO. 6,JUNE 2009 Wei-Liang Tai, Chia-Ming Yeh, Chin-Chen Chang 報告者 : 許睿中 日期 :6.20

2. Outline Introductions Proposed Experimental results Conclusions

3. Introductions Ni et al. proposed ”Reversible data hiding” ◦ While multiple pairs of peak and minimum points can be used for embedding, the pure payload is still a little low. ◦ Multiple pairs of peak and minimum point must be transmitted to the recipient.

4. Proposed 223322 x i-1 : predictive pixel x i : original pixel 20100 x d peak 23 y 20100 Secret=101 y i =x i +b =2+1 =3

5. Proposed 223322 x i-1 : predictive pixel x i : original pixel 20100 x d peak 2320100 Secret=101 y i =x i -1 =2-1 =1 213 y 231324313234313

6. Proposed peak

7. Proposed 234313 y 2 x d i =y i -x i-1 =3-2 =1 x i =y i -1 =3-1 =2 2 b=1

8. Proposed 234313 y peak 2 x d i =y i -x i-1 =4-2 =2 x i =y i -1 =4-1 =3 23322

9. Proposed-Binary Tree Structure Binary Tree Structure number of peak point=2 L

10. Proposed-Prevent Overflow or Underflow

11. Proposed-Embedding x d Secret=101 y i =x i -2 L =133-4 =129 150132130129136139133150-18-273-6 -255+2 L+1 255-2 L+1 0 2L2L -2 L Embedding level L=2 y 150129 -6

12. Proposed-Embedding x d Secret=101 y i =x i +(d i +b) =139+(3+1) =143 150132130129136139133150-18-273 -255+2 L+1 255-2 L+1 0 2L2L -2 L Embedding level L=2 y 150129 -6 Secret=101 143

13. Proposed-Embedding x d Secret=101 y i =x i +2 L =136+4 =140 150132130129136139133150-18-273 -255+2 L+1 255-2 L+1 0 2L2L -2 L Embedding level L=2 y 150137 -6 143140128127128

14. Proposed-Embedding -255+2 L+1 255-2 L+1 0 2L2L -2 L 2 L+1 -2 L+1

15. Proposed-Extraction y x i =y i +2 L =128+4 =132 150128127128140143129 -255+2 L+1 255-2 L+1 0 2 L+1 -2 L+1 Embedding level L=2 x 150 d i =y i -x i-1 =128-150 =-22 132

16. Proposed-Extraction y 150128127128140143129 -255+2 L+1 255-2 L+1 0 2 L+1 -2 L+1 Embedding level L=2 x 150 d i =y i -x i-1 =127-132 =-5 132 b=1 130129136139133

17. Experimental results

18. Conclusion In this letter, we have presented an efficient extension of the histogram modification technique by considering the differences between adjacent pixels rather than simple pixel value. One common drawback of virtually all histogram modification techniques is that they must provide a side communication channel for pairs of peak and minimum points. To solve this problem, we introduced a binary tree that predetermines the multiple peak points used to embed messages; thus, the only information the sender and recipient must share is the tree level L.