MTVSS: (M)isalignment (T)olerant (V)isual (S)ecret (S)haring on resolving alignment difficulty

A (k, n)-threshold visual secret sharing (VSS) scheme has the distinctive property of easy decryption by manually printing out shadow images on transparencies and stack them to visually reveal the secret image. However, the decoding is highly dependent on the precise alignment of transparencies by hand. The misalignment makes the secret in reconstructed image invisible, and this is referred to as the misalignment problem. In this paper, we consider the misalignment problem in VSS scheme. We design a misalignment tolerant VSS (MTVSS) scheme based on the trade-off between the usage of big and small blocks to address this misalignment problem. Our MTVSS scheme allows people visually reveal the original secret image, and it is not necessary to align the transparencies precisely.