JIS  Vol.6 No.4 , October 2015
Enhanced Contrast of Reconstructed Image for Image Secret Sharing Scheme Using Mathematical Morphology
Abstract: Visual secret sharing (VSS) is one of the cryptographic techniques of Image secret sharing scheme (ISSS) that performs encoding of secret message image (text or picture) into noise like black and white images, which are called as shares. Shares are stacked together and secret message image is decoded using human visual system. One of the major drawbacks of this scheme is its poor contrast of the recovered image, which improves if computational device is available while decoding. In this paper, we propose to improve poor contrast of classical VSS schemes for text or alphanumeric secret messages and low entropy images. Initially, stacked image is binarized using dynamic threshold value. A mathematical morphological operation is applied on the stacked image to enhance contrast of the reconstructed image. Moreover, a method is proposed that allows the size of the structuring element to change according to the contrast and the size of a stacked image. We perform experiments for different types of VSS schemes, different share patterns, different share types (rectangle and circle), and low entropy images. Experimental results demonstrate the efficacy of the proposed scheme.
Cite this paper: Meghrajani, Y. and Mazumdar, H. (2015) Enhanced Contrast of Reconstructed Image for Image Secret Sharing Scheme Using Mathematical Morphology. Journal of Information Security, 6, 273-279. doi: 10.4236/jis.2015.64027.

[1]   Naor, M. and Shamir, A. (1995) Visual Cryptography. In: Proceedings of the Advances in Cryptology— EUROCRYPT’94, Lecture Notes in Computer Science (Volume 950), 1-12.

[2]   Chen, S.-K. and Lin, S.-J. (2012) Optimal (2,n) and (2, Infinity) Visual Secret Sharing by Generalized Random Grids. Journal of Visual Communication and Image Representation, 23, 677-684.

[3]   Feng, J.-B., Wu, H.-C., Tsai, C.-S., Chang, Y.-F. and Chu, Y.-P. (2008) Visual Secret Sharing for Multiple Secrets. Pattern Recognition, 41, 3572-3581.

[4]   Yang, C.-N. and Chen, T.-S. (2005) Aspect Ratio Invariant Visual Secret Sharing Schemes with Minimum Pixel Expansion. Pattern Recognition Letters, 26, 193-206.

[5]   Yang, C.N. (2004) New Visual Secret Sharing Schemes Using Probabilistic Method. Pattern Recognition Letters, 25, 481-494.

[6]   Shyu, S.J., Huang, S.Y., Lee, Y.K., Wang, R.Z. and Chen, K. (2007) Sharing Multiple Secrets in Visual Cryptography. Pattern Recognition, 40, 3633-3651.

[7]   Lin, S.-J., Chen, S.-K. and Lin, J.-C. (2010) Flip Visual Cryptography (FVC) with Perfect Security, Conditionally-Optimal Contrast, and No Expansion. Journal of Visual Communication and Image Representation, 21, 900-916.

[8]   Hou, Y.C. and Quan, Z.Y. (2011) Progressive Visual Cryptography with Unexpanded Shares. IEEE Transactions on Circuits and Systems for Video Technology, 21, 1760-1764.

[9]   Wu, H.-C. and Chang, C.-C. (2005) Sharing Visual Multi-Secrets Using Circle Shares. Computer Standards & Interfaces, 28, 123-135.

[10]   Lin, S.-J. and Lin, J.-C. (2007) VCPSS: A Two-in-One Two-Decoding-Options Image Sharing Method Combining Visual Cryptography (VC) and Polynomial-Style Sharing (PSS) Approaches. Pattern Recognition, 40, 3652-3666.

[11]   Yang, C.-N. and Ciou, C.-B. (2010) Image Secret Sharing Method with Two-Decoding-Options: Lossless Recovery and Previewing Capability. Image and Vision Computing, 28, 1600-1610.

[12]   Wu, X. and Sun, W. (2013) Random Grid-Based Visual Secret Sharing with Abilities of OR and XOR Decryptions. Journal of Visual Communication and Image Representation, 24, 48-62.

[13]   Salehi, S. and Balafar, M.A. (2014) Visual Multi Secret Sharing by Cylindrical Random Grid. Journal of Information Security and Applications, 19, 245-255.

[14]   Wu, X. and Sun, W. (2012) Random Grid-Based Visual Secret Sharing for General Access Structures with Cheat-Preventing Ability. Journal of Systems and Software, 85, 1119-1134.

[15]   Lee, K.H. and Chiu, P.L. (2011) A High Contrast and Capacity Efficient Visual Cryptography Scheme for the Encryption of Multiple Secret Images. Optics Communications, 254, 2730-2741.

[16]   Viet, D.Q. and Kurosawa, K. (2004) Almost Ideal Contrast Visual Cryptography with Reversing. In: Proceedings of Topics in Cryptology—CT-RSA 2004, Lecture Notes in Computer Science (Volume 2964), 353-365.

[17]   Otsu, N. (1979) A Threshold Selection Method from Gray-Level Histogram. IEEE Transactions on System Man Cybernetics, 9, 62-66.