On the Generality of (k, n) XOR-based Visual Cryptography Scheme

The necessary condition of the optimal pixel expansion is given and proved in (k, n) XOR-based Visual Cryptography Scheme (XVCS). A new method is designed for constructing (k, n)-XVCS by use of basis matrices. The method is proved to be suitable for (k, n)-XVCS with 2 kn. Based on the above results, the secret sharing and recovering algorithms are proposed. The experimental results show that the pixel expansion can be decreased efficiently. Furthermore, the secret images can be recovered perfectly.