The following publications are possibly variants of this publication:
- Contrast optimal colored visual cryptography schemesStelvio Cimato, Roberto De Prisco, Alfredo De Santis. itw 2003: 139-142 [doi]
- Optimal Colored Threshold Visual Cryptography SchemesStelvio Cimato, Roberto De Prisco, Alfredo De Santis. dcc, 35(3):311-335, 2005. [doi]
- On the Contrast in Visual Cryptography SchemesCarlo Blundo, Alfredo De Santis, Douglas R. Stinson. iacr, 1996:13, 1996. [doi]
- On the Contrast in Visual Cryptography SchemesCarlo Blundo, Alfredo De Santis, Douglas R. Stinson. joc, 12(4):261-289, 1999. [doi]