On ridges and valleys [image registration]

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 two dual entities have received comparatively little attention from the computer vision community with regard to other like edges or comets. 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