Image denoising via gradient approximation by upwind scheme

A novel hybrid filter based on gradient approximation by upwind scheme is proposed to restore images corrupted by impulsive and Gaussian noises, and simultaneously to preserve the details. In this work, the gradient is approximated by the hybrid upwind scheme, and then the impulses are separated according to the characteristic classification. The remaining pixels are processed by Gaussian filter (GF) with their corresponding weights that are acquired from the hybrid upwind scheme and are distinct in edges and smooth domains. The simulation results demonstrate that the proposed filter achieves better performance in restoring the images corrupted by different noise while the details are preserved.