VERFAHREN ZUR BESTIMMUNG DER LOKALEN ORIENTIERUNG EINES KONTURSEGMENTES UND ZUR BESTIMMUNG VON LINIEN UND ECKEN

摘要

A method of determining the direction of a segment of a contour in a local region of a binary profile image. The number of pixels having a predetermined value and existing in a plurality of radial directions whose center is one of the pixels in a local region having the predetermined value is determined, and the segment is judged to exist in a direction in which the number of pixels is greater. Furthermore, when the number of pixels of the predetermined value existing in a direction is greater by a predetermined value than the sum of the numbers of pixels of the predetermined value existing on both adjacent directions, the segment is judged to exist in the direction. Two directions in which the numbers of pixels are greater are detected for each pixel of the contour points. Whether these two directions are points constituting a segment or points constituting a segment in a quasi-line direction or points near a corner are determined depending on whether or not they are in a 180 DEG direction or how much they are different from a 180 DEG direction. Points constituting a segment, which are adjacent to each other and have the same direction, are detected as a segment. The position and direction are determined from each point near the corner, and representative values of the position and direction of the mutually adjacent points near the corner are determined.