Progressive (k,n) secret image sharing Scheme with meaningful shadow images by GEMD and RGEMD

In (k,n) progressive secret image sharing (PSIS) schemes, a secret image is shared into n shadows in such way that: (1) fewer than k-1 shadows get no information on the secret image; (2) k to n shadows can progressively recover the secret image. In most PSIS schemes, the shadows are noise-like images which would cause suspicious of attackers. The combination of secret image sharing and steganography can share a secret image into meaningful shadow images that can reduce attention of attackers. However most existing secret image sharing schemes with meaningful shadow images do not possess progressive property, a group of shadow images can either reconstruct entire secret image or get nothing on it. In this paper, we construct a new (k,n) PSIS with meaningful shadow images using GEMD and RGEMD. The property of progressive reconstruction is proved both in theoretical analysis and experimental results. The approaches of GEMD and RGEMD enable our Scheme high embedding capacity and resistance of RS detection. Comparing with other PSISs with meaningful shadow images, our Scheme has advantages in shadow size and shadow visual quality.