Analysis of the ratio expansion watermarking scheme and its improvement

Ratio expansion is a recently proposed, remarkable method for reversible data hiding in 3D meshes. The capacity and distortion are the two most common performance measures for data hiding. This paper analyses the ratio expansion method, and a novel mathematical framework is introduced and described, which proves that the magnitude of the distortion depends on three parameters. By appropriately selecting two of these parameters and a factor called "reference value", the proposed method achieves reduction of the distortion. Another novel coding and decoding phrase is also proposed to get higher capacity. The experimental results show that this method improves the embedding capacity significantly without affecting the visual quality of 3D mesh model.