Feature preserving bidirectional fuzzy flow for image sharpening

In this paper, we propose a bidirectional fuzzy flow framework based on fuzzy sets, which performs a fuzzy backward (inverse) diffusion along the gradient direction to the isophote lines (edges), while a certain forward diffusion along the tangent direction on the contrary. To preserve the natural transition of image features, the eigenvalues of local image structure tensor are used to detect different features, which are sharpened correspondingly.