Mean value based reversible data hiding in encrypted

Mean value based reversible data hiding in encrypted images Source：Optik, vol. 130, pp. 922 -934, 2017 Authors：Smita Agrawal, Manoj Kumar Speaker ：Xiaoshuang Li Date ： 2018/04/26

Outline • Introduction • Proposed Scheme • Experimental Results • Conclusions

Introduction (1) 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.

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

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

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

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.

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

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 Therefore, , embedded watermark bit is 0, . .

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

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

Proposed Scheme(9/9) (a) 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.

Experimental results(1/7) (a)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).

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).

Experimental results(3/7)

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.