Multi-scale curvatures for contour feature extraction

A method is described to extract features of contour of a figure based on its curvature. For a digital figure, curvatures are approximated by using differences of contour tangential angles at two points apart from each other with an appropriate distance scale. In this method, a set of curvatures with various scales is calculated, and from the curvature changes with respect to the multiple scales, the features of the original contour, such as the locations and angles of vertices, are extracted. The view-field resolutions for the analysis of features of figures are determined automatically, for each figure and its parts.