Extended visual cryptography techniques for true color images

Abstract

In this work, two extended visual cryptography techniques for sharing color images are proposed. Three meaningful shares are generated in both techniques using a block size of 5 × 5 corresponding to each pixel of original secret image. First proposed technique is (3, 3)-EVCT in which first share contains R component, second contains G component and third contains B component of the secret image. All three shares are required to reconstruct the original secret image on the receiver side. Second technique is (2, 3)-EVCT in which any 2-out-of-3 shares are needed to recover the original secret image on the receiver side. Out of these shares, first share contains the RG components, second contains GB components and third contains RB components of the secret image. All shares in both techniques are meaningful as they contain the cover images along with the information of the original secret image. These shares are made meaningful in order to increase the security and to avoid the suspicion that something is hidden there. The proposed techniques are lossless in nature and are less complex. The dimensions of the original secret image, cover images, regenerated secret image are same. The effectiveness of the proposed techniques have been shown by comparing their results with the results of the existing techniques on the basis of various parameters.