A curve bend function based method to characterize contour shapes

摘要

In this paper, a new Curve Bend Function (CBF) based method is presented to extract main features of a contour. It utilizes two quantities, one called a Curve Bend Angle (CBA), and the other known as a type coefficient of curve segment defined on a contour. The CBA measures the bending degree at each point on the contour, while the type coefficient characterizes the properties (convexity and concavity) of simple curve segments. The CBF combines the advantages of the two quantities and provides an overall description of a contour. A local maximum or minimum of the CBF corresponds to a critical point of the contour, and the peak value is the cosine of the CBA. Hence, the problem of locating critical points of a contour is reduced to the problem of finding peak points of the CBF. The sign of a peak value indicates the related CBA being an inner or outer angle. Our experimental results and comparisons between the CBF method and Rosenfeld-Johnston's method show that our method is effective and accurate in generating the description of a contour.