Boolean-based Two-in-One Secret Image Sharing by Adaptive Pixel Grouping.

The two-in-one secret image sharing (TiOSIS) technique is a hybrid scheme that protects a secret image by combining visual cryptography (VCS) and polynomial-based secret image sharing (PSIS). There are two decoding methods available in TiOSIS: stacking-to-see decryption and lossless image recovery. However, the majority of current TiOSIS methods use Lagrange interpolation to precisely reconstruct the secret, which would result in intense computations. In this paper, an efficient TiOSIS scheme using Boolean XOR operation for lossless image recovery is proposed. The proposed scheme consists of three building blocks: shared data generation, shadow construction, and image decryption. In shared data generation, the grayscale secret image is processed by a Boolean-based SIS to derive the shared bits. In shadow construction, an adaptive pixel grouping strategy is utilized to determine a grouping pattern. The halftone image adjustment algorithm is adopted to generate a suitable halftone image. With the grouping pattern and halftone image, we construct the shadows via the group-pixel embedding and sharing approach. In image decryption, we can reveal the secret image by stacking-to-see decoding or Boolean-based lossless image recovery. Extensive experiments and comparisons are illustrated to show the effectiveness and benefits of the proposed scheme.