Implementation and Analysis of Different Visual Cryptographic Schemes

Nowadays images became ubiquitous on Internet and mobile applications. Image secret sharing is a subset of secret sharing scheme. Visual Cryptography (VC) is one of the secure ways to transfer images over network. Visual cryptography is a special approach to the general secret sharing problem. In (k, n) image secret sharing, the image that carries the secret is broken into n pieces (called as shares) and decryption is totally impossible unless at least k pieces are collected and superimposed. The biggest advantage of this technique is decryption that is done via naked eye. There is no need of any mathematical computation. Here, exploration and exploitation of various visual cryptographic algorithms for grayscale, black and white (binary) as well as coloured images are given. This paper gives a comprehensive analysis of various image encryption algorithm based on metric such as Peak Signal to Noise Ratio (PSNR) and Mean Normalized Cross-Correlation. Here, results for implementation of various (2, 2) VC scheme image encryption are given. Most of these schemes can be extended to (n, n) VC scheme.