Probabilistic Grayscale Visual Cryptography Scheme Using Multi-Pixel Encoding

This paper proposed a general implementation of multi-pixel encoding method based on grayscale probabilistic matrix which help improve the performance of grayscale probabilistic visual cryptography. Firstly, we presented an algorithm to generate the probabilistic matrix for grayscale palette of any size. Then, we realized a new way of multi-pixel encoding by introducing the idea of probability reduction. Meanwhile, the multitone-based analysis by synthesis technique was used to improve the perceptual quality of the reconstructed images. Experimental results show that our scheme effectively improves the smoothness and expressiveness of grayscale probabilistic visual cryptography.