Generalized Explicit Schemes for Coherence Enhancing Diffusion Filtering

This paper presents the generalized explicit schemes (GES) for the coherence enhancing diffusion (CED) filtering, which is one of a wide variety of nonlinear diffusion filtering. Unlike the traditional standard explicit scheme which updates the diffusion coefficients in each iteration, the generalized ones use several new updating types, including the fixed diffusion coefficients, the uniform interval update (UIU) and the optimized interval update (OIU) of diffusion coefficients. The GES significantly improve efficiency by reducing the computational amount of updating the diffusion coefficients, compared with the existing acceleration methods by enlarging the time step, such as implicit or semi-implicit schemes, or a scheme with larger mask of spatial discretization. Also the OIU may allow the GES to achieve high accuracy by using only two to four updating of the diffusion coefficients during the whole process. Experiments demonstrate the efficiency of the GES is comparable to those existing acceleration methods, meanwhile, the GES with the OIU outperform the other methods in the tradeoff between efficiency and accuracy.