Fault-tolerant and non-expanded visual cryptography for color images

摘要

Most of the studies in visual cryptography (VC) are for binary images. Hou's method [Pattern Recog. 2003, Vol. 36, 1619-1629] is a good extension from binary to colors. In this study, we extend Hou's method further so that the new scheme has fault-tolerant ability and the size is non-expanded in shares. Namely, the secret image can still be revealed if one of the generated shares delays due to communication channel failure, or by natural crash of the storage equipment, or even destroyed by hackers; and the space of the storage equipment can be saved due to the non-expansion in size of the generated shares. In the proposed scheme, a color secret image decomposes into three shares, which are non-expanded in size. Each share alone cannot reveal the secret image. However, gathering "any" two of the three shares can unveil the secret image.