On ridges and valleys

Ridges and valleys are earth's relief structures. They can have an imaging counterpart provided we model a digital image as a landscape by considering grey level values as height. These nvo dual entities have received comparatively little attention from the computer vision community with regard to others like edges or corners. In this paper we first propose a taxonomy or classification of the several definitions of ridge and valley lines and review their implementation on discrete images. Then, we illustrate the application of one type of characterization, a creaseness measure, to solve several problems of image registration, where ridge and valley lines are taken as landmarks. © 2000 IEEE.