Detection and enhancement of line structures in an image by anisotropic diffusion

Abstract

This paper describes a method to enhance line structures in a gray-level image. For this purpose, we blur the image using anisotropic Gaussian filters along the directions of each line structure. In a line structure region the gradients of image gray levels have a uniform direction. To find such line structures, we evaluate the uniformity of the directions of the local gradients. Before this evaluation, we need to smooth out small structures to obtain line directions. We, first, blur the given image by a set of Gaussian filters. The variance of the filter which maximizes the uniformity of the local gradient directions is detected position by position. Then, the line directions in the image are obtained from this blurred image. Finally, we blur the image using an anisotropic filter again along the directions, and enhance every line structure.