Gray Visual Cryptography Algorithm for Secret Sharing

Visual cryptography technique is a secret sharing scheme used to encode secret visual information, in such a way that decoding process can be performed by a human visual system without any devices or complex computations to reveal the original secret. In this paper, we proposed a visual cryptography scheme for embedding gray secret image into two meaningful shares, and analyzed the relationship between the secret image and the meaningful shares, focusing our attention on improving the visual quality of the revealed secret by measuring the closeness or the differences in similarity between the secret image and the meaningful covers. Experimental results and case studies show that using covers that are less different from secret helps in obtaining a relatively good visual quality reconstructed secret image than using any covers.