A Sudoku-based Secret Image Sharing Scheme with Reversibility (Invited Paper)

A common drawback of the image sharing with steganography approaches is that the revealed secret image is distorted due to the truncation of the grayscale secret image. To lossless reveal the secret image in the (t, n)-threshold, we provide a novel sharing scheme in this article. Moreover, the original host image can be recovered by the embedded shadow images. To accomplish the above purposes, the proposed scheme derives the secret shadows and generates the meaningful shadow images by adopting the sudoku. In the new scheme, the sudoku grid is setting to 16x16 and divided into sixteen 4x4 blocks. Thus, we can embed 4x(t-1) secret bits into each pixel pair of the host image. Besides, the embeddable secret capacity can be improved according to the threshold t in the (t, n)-threshold sharing system. The experiments show that the shadows can be successfully camouflaged in the host image with satisfactory quality. The distortion of the embedded host pixels is limited within range [0, 3]. Moreover, the proposed scheme provides a large capacity for embedded secret data.