A novel authenticatable color visual secret sharing scheme using non-expanded meaningful shares

In this paper, a novel visual secret sharing scheme is presented to hide a secret image into two meaningful cover images which are called share images with no pixel expansion. Simultaneously, the proposed scheme embeds an extra confidential image in these two share images. People who gather the two share images can obtain the secret image by stacking them without any complex computation. After one of the share images is shifted for certain unit, people can get the extra confidential image by their visual system to check the validity of the revealed secret image. Except for sharing binary secret image, the proposed scheme can also be applied to color visual secret sharing scheme to hide color secret image into two meaningful color halftone images without any pixel expansion, and people can derive the extra confidential image for authentication by shifting one of the share images.