Nidhin Soman and Smruthy Baby
Mar Baselios Institute of Technology and Science, India

Visual cryptography scheme is a cryptographic technique which allows visual information.It is solve the poor visual quality problem.XOR-based VC. Actually, two XOR-based VC algorithms are proposed, namely XOR-based VC for general access structure (GAS) and adaptive region incrementing XOR-based VC.to be encrypted in such a way that the decryption can be performed by the human visual system,without the help of computers. There are diverse visual cryptography schemes developed based on different factors like pixel expansion, meaningless or meaningful shares, contrast, security, type of secret image and the number of secret images encrypted. This paper discusses most of the visual cryptography schemes and the performance measures used to evaluate them.

Visual cryptography, random grid, pixel expansion, extended visual cryptography,XOR general access structure, region incrementing, pixel expansion, adaptive security level