A novel reversible data hiding scheme

A novel reversible data hiding scheme based on an improved difference expansion (DE) method, which introduces the companding technique into traditional DE, is proposed in this paper. The method focuses on largely increasing the number of the differences to be expanded. The location map recording these expanded positions can be efficiently compressed due to significant difference between possibilities for expanded and non-expanded differences. Thereby, the hiding capacity is largely increased. We compress large differences into smaller values, and then expand these values. Hence, the higher PSNR value can be achieved than that caused by directly expanding large differences. As revealed in the experimental results, the proposed scheme outperforms traditional DE, in terms of embedding capacity and visual quality, as expected.