Improved reversible data hiding based on two-dimensional difference-histogram modification

Recently, a reversible data hiding (RDH) method based on difference-pair-mapping (DPM) is proposed for better employing the image redundancy. The DPM is a specifically designed injective mapping defined on difference-pairs, and it is an extension of the conventional expansion and shifting techniques used in prior histogram-based RDH. However, any injective mapping defined on difference-pairs with allowed modification directions can derive a RDH method and the embedding performance is closely related to the employed mapping. Then, enhanced performance can be expected if a better DPM is adopted. Based on this consideration, a new RDH method is presented in this paper to improve the previous DPM-based RDH. Specifically, based on the statistical distribution of difference-pairs, a new DPM is designed to better utilize the difference-pairs with high frequencies. Moreover, a fine adjusting strategy is introduced to further optimize the embedding performance by adaptively adjusting the proposed DPM. With the proposed DPM and the adjusting strategy, our method outperforms the previous DPM-based RDH. The superiority of our method over some other state-of-the-art works is also experimentally verified.