An Efficient (t,n) Threshold Secret Image Sharing Scheme Based on Thien-Lin Secret Image Sharing

In a (t, n) threshold secret image sharing scheme (TSIS), a secret image is first encoded into n pieces, normally referred as shares or shadow images. Those share-images can be stored or transferred safely as individually a share-image cannot reveal any detail about the secret image. The receiver or user of the share-images referred as participants. If at least t(≤n) share-images are submitted by the participants, the secret image can be recomputed. One of the most popular secret image sharing schemes was proposed by Thien-Lin (2002). The authors had proposed two versions of the scheme. The first version of SIS by Thien-Lin is efficient, but lossy as the pixel values more than 250 (< 256) are truncated to 250. The second one is lossless, but it increases the size of the secret image during preprocessing. In this paper, we propose a secret image sharing scheme based on Thien-Lin scheme. We consider a little loss in the reconstructed image which is maximum one per pixel (the loss can be one to five in Thien-Lin scheme) and keep the size of the secret image same. Although buffer pixels may be added for the sake of programming, after reconstruction of the secret image the buffer pixels are easily identifiable and can be safely removed.