Visual cryptography is a entirely secure method to save from harm secrets and is differentiated by its original decryption process. A visual cryptography method is a process to divide a secret image into a set of shares so that a number of authorized shares can right of entry to the secret while other unauthorized shares cannot reveal out any secret information. In recent times, visual cryptography or its perception is fundamentally assumed to protect the rational possessions rights for digital images. On the other hand, some of the schemes do not assure the security conditions of visual cryptography; thus they cannot be used to protect the copyright of the images. Additionally, many techniques are not appropriate for gray-level or color watermarks.
 M. Naor, A. Shamir, ―Visual cryptography‖, in: A. De Santis (Ed.), Advances in Cryptology: Eurpocrypt‘94, Lecture Notes in Computer Science, vol. 950, pp. 1–12, 1995.  M. Naor and A. Shamir “Visual cryptography 2: Improving t h e c o n t r a s t via t h e cover base,” 1996, a preliminary version appears in ―Security Protocols”, M. Lomas ed. Vol. 1189 of Lecture Notes in Computer Sciencee, Springer-Verlag, Berlin, pp.197-202, 1997.  Chang, C. C., Chuang, J. C., ―An image intellectual property protection scheme for gray-level images using visual secret sharing strategy,‖ Pattern Recognition Letters, Vol. 23, pp. 931−941, 2002.  Chen, C. T. and Lu, T. C.―A mobile ticket validation by VSS tech with time-stamp,‖ Proceedings of the 2004 IEEE International Conference on e-Technology, e-Commerce and e-Service, Taipei, Taiwan, pp. 267−270, 2004.  Zhou, G. R. Arce, and G. Di Crescenzo, ―Halftone Visual Cryptography,‖ IEEE transactions on Image Processing, 2006.  M. Naor and B. Pinkas, ―Visual authentication and identification,‖ Crypto97, LNCS, vol. 1294, pp. 322–340, 1997.  A. Bonnis and A. Santis, ―Randomness in secret sharing and visual cryptography schemes,‖ Theory. Computer. Science, 314, pp 351- 374, 2004.  R. Hwang, ―A digital Image Copyright Protection Scheme Based on Visual Cryptography,‖ Tambang Journal of science and Engineering, vol.3, No.2, pp. 97-106, 2000.  E.Myodo, S. Sakazawa, Andy. Takishima, ―Visual cryptography based on void-and-cluster half toning technique,‖ in Proc. IEEE ICIP, Atlanta, GA, Oct., 2006.  Z. M. Wang, G. R. Arce, and G.Di Crescenzo, ―Halftone visual cryptography via error diffusion,‖ IEEE Trans. Inf. Forensics Security, vol.4, no. 3, pp. 383–396, 2009.  D. S. Tsai, T. Chenc, and G. Horng, ―On generating meaningful shares in visual secret sharing scheme,” Image Sci. J., vol. 56, pp. 49-55, 2008.  N. Askari, H.M. Heys, and C.R. Moloney ―An extended visual cryptography scheme without pixel expansion for halftone images‖, 26th IEEE Canadian Conference of Electrical and Computer Engineering (CCECE) 978-1-4799-0033, 2013.  Y.C. Hou and S. F. Tu, ―A visual cryptographic technique for chromatic images using multi-pixel encoding method,‖ Journal of Research and Practice in Information Technology, vol. 37, no. 2, pp. 179–191, 2005.
Security, Visual Cryptography, half tone images, embedding, extraction, dithering matrix.