A Novel Method for the Construction of Threshold Multiple-secret Visual Cryptographic Schemes by without Pixel Expansion

The main concept of the original visual secret sharing (VSS) scheme is to encrypt a secret image into n meaningless share images. It cannot leak any information of the shared secret by any combination of the n share images except for all of images. The shared secret image can be revealed by printing the share images on transparencies and stacking the transparencies directly, so that the human visual system can recognize the shared secret image without using any devices. The visual secrets sharing scheme for multiple secrets is called multiple-secret visual cryptographic schemes (MVCSs). This paper proposed general constructions for threshold multiple-secret visual cryptographic schemes (MVCSs) that are capable of encoding s secret images. This presented MVCS schemes utilize a predefined pattern book with pixel expansion to encrypt secret images into share images. In our research, we propose a novel MVCS scheme that can share two binary secret images on two rectangular share images with no pixel expansion, but also has an excellent recovery quality for the secret images.