Reversible Shared Data Hiding Based on Modified Signed Digit EMD

The reversible data hiding schemes not only extract the embedded secret data from the stego-image but also recover the original cover image. This can be extended for use with multiple parties where the embedded secret data is undecipherable unless all members contribute. Recently, Chang et al. [2] proposed a reversible data hiding scheme based on EMD (Exploiting Modification Direction) which can be used for this purpose. However, the capacity of EMD decreases quickly with the increased number of stego-images. To address this disadvantage, we will propose a reversible data hiding scheme based on modified signed digit EMD in this paper. According to our experiments, this scheme achieves the requirement of reversible shared data hiding and keeping good image quality but also maintains embedding capacity of least 1 bpp (bits per pixel).