Two-image encryption by random grids

Visual secret sharing (VSS) is a technology that encrypts a secret image into several share images. When superimposes the shares, it can restore the secret by human vision. This paper proposes a novel image visual secret sharing scheme to encrypt two secret images in the same time. This scheme turns two secret images into two meaningless shares without any pixel expansion and codebook. In order to restore the two secret images, users can directly superimpose these two shares to disclose the first secret image. For restoring the second image, users superpose the same two shares in a way of moving horizontally one share. Although the second secret image will get distortion when it be restored in the proposed scheme, but this scheme reduces great quantity of the distortion than Chen et al.'s scheme which was proposed in 2008. In addition, the proposed scheme can be used for any size of the rectangle secret images. Finally, the proposed scheme can also combine with augmented reality (AR) to promote convenience and security of human's life, hence the proposed scheme can be widely applied in real world.