A new generalized colour visual cryptography scheme

Visual cryptography was first introduced by Naor and Shamir and the scheme has the benefit of requiring no cryptographic computation on the part of decoders. The modified visual cryptography is a new scheme, which requires little cryptographic computation on the part of decoders. In this paper, a new generalized (k,n) gray visual cryptography scheme is proposed based on modified visual cryptography. This scheme provides a more efficient way to hide a gray image which has 256-colors in n different shared images. Also, for a computer system, two types of unconditional security generalized (k,n) color visual cryptography scheme are proposed.