1. Mean value based reversible data hiding in encrypted images
Source：Optik, vol.130, pp , 2017
Authors：Smita Agrawal, Manoj Kumar
Speaker ：Xiaoshuang Li
Date ： /04/26

2. Outline
Introduction
Proposed Scheme
Experimental Results
Conclusions

3. Introduction vacating room for embedding after encryption
[1] W. Hong, T.S. Chen, H.Y. Wu, An improved reversible data hiding in encrypted images using side match, IEEE Signal Process. Lett. 19 (4) (2012)199–202.
[2] X.Liao, C.W. Shu, Reversible data hiding in encrypted images based on absolute mean difference of multiple neighbouring pixels, J. Vis. Commun.Image Represent. 28 (2015) 21–27.
(2) reserving room for embedding before encryption
[1] K.D. Ma, W.M. Zhang, X.F. Zhao, N.H. Yu, F.H. Li, Reversible data hiding in encrypted images by reserving room before encryption, IEEE Trans. Inf.Forensics Secur. 8 (3) (2013) 553–562.
[2] X. Cao, L. Du, X.X. Wei, D.M. Meng, X.J. Guo, High capacity reversible data hiding in encrypted images by patch-level sparse representation, IEEETrans. Cybern. 46 (5) (2015) 1132–1143.

4. Proposed Scheme(1/9)
The flowchart of the proposed scheme

5. Proposed Scheme(2/9) Preserving mean values
Where denotes the th pixel value of the th set of the image I
and
𝑙 𝑖𝑗

6. Proposed Scheme(3/9) Encryption procedure
Where J is an encrypting image, R is a pseudorandom number matrix, and and for an image of size

7. Proposed Scheme(4/9) Embedding procedure
Watermark bit is added in all pixel values of the corresponding set of the image E except first pixel which holds the mean value of that particular set. In this way, encrypted watermarked image C is obtained.

8. Proposed Scheme(5/9) Decryption procedure
Where and for an image of size

9. Proposed Scheme(6/9) Watermark extraction
Where denotes the th pixel value of the th set of the image D and
If consider the first set , embedded watermark bit is 0,
Therefore,

10. Proposed Scheme(7/9)
If embedded watermark bit is 1, Therefore, .

11. Proposed Scheme(8/9) Image recovery
Where (which holds the original mean value) represents the first element of the set , is the recovered value of the first pixel for the set

12. Proposed Scheme(9/9) sample pixel values;
(b) modified values after preserving mean;
(c) pseudorandom numbers;
(d)encrypted pixels;
(e) encrypted watermarked pixels;
(f) directly decrypted watermarked pixels;
(g) pixel values after watermark extraction;
(h) Recovered pixels.

13. Experimental results(1/7)
Original Lena image;
(b)encrypted Lena image;
(c) encrypted and watermarked Lena image;
(d) directly decrypted Lena image containing watermark;
(e) recovered Lena image (after watermark extraction).

14. Experimental results(2/7)
Histogram analysis:
(a) histogram of original image;
(b) histogram of encrypted image;
(c) histogram of encrypted and watermarked image;
(d)Histogram of directly decrypted image containing watermark;
(e) histogram of recovered image (after watermark extraction).

15. Experimental results(3/7)

16. Experimental results(4/7)
[37] X. Zhang, Reversible data hiding in encrypted image, IEEE Signal Process. Lett. 18 (4) (2011) 255–258.
[38] W. Hong, T.S. Chen, H.Y. Wu, An improved reversible data hiding in encrypted images using side match, IEEE Signal Process. Lett. 19 (4) (2012)199–202.

17. Experimental results(5/7)

18. Experimental results(6/7)

19. Experimental results(7/7)

20. Conclusions
A novel reversible data hiding technique for encrypted images.
Suitable for privacy protection applications for sensitive fields.

21. Thank you!