Feature-Oriented Coupled Bidirectional Flow for Image Denoising and Edge Sharpening

In this paper, a new type of diffusion process that simultaneously denoises and sharpens images is considered. We presents a feature-oriented coupled bidirectional flow process, where, according to image features such as edges, textures, and fine parts, it can switch from a forward diffusion to a backward (inverse) one along the normal directions to the isophote lines (edges), while a forward diffusion is performed along the tangent directions. To eliminate the conflict between the backward and the forward force, we split them into a coupled scheme. In order to enhance image features the nonlinear diffusion coefficients are locally adjusted according to the directional derivatives of the image. Experimental results demonstrate that our algorithm can substantially enhance features on denoising smoother areas of the image.