Circularity — a new principle underlying the design of accurate edge orientation operators

摘要

Currently available fast edge detection operators are reviewed. Their rationale is studied with particular reference to the estimation of angular orientation of edges. The idea of ‘circular’ edge detection operators is developed, and used to explain the surprising accuracy of the Sobel operator. A family of circular operators is designed for use in neighbourhoods of various sizes, and general ideas on edge operator design are developed. The concept of ‘closed bands’ of pixels for making neighbourhoods close to circular should be widely applicable in digital image analysis, not just in the ambit of fast edge detection.