A multi-scale edge detector

摘要

A multi-scale edge detector with subpixel accuracy is described. A subpixel Laplacian edge detector, recursively implemented, is run at different scales and the recovered edge information is combined. The multi-scale edge detection is based on the behavior of edges in scale space and takes into account their physical phenomena. With this purpose in mind, four-step edge models are considered: the ideal, the blurred, the pulse and the staircase. It is emphasized that the use of two scales (the larger and the smaller) is sufficient for good edge detection. Furthermore, a set of rules is derived for combining edge information obtained from a Laplacian detector which has some special properties. However, this type of edge detector gives at least two classes of false edges, one of which cannot be eliminated by the usual thresholding methods. An appropriate thresholding algorithm is given taking into account the origin of the false edges and their behavior in scale space.