Patent ID: 6813383
Filing Date: 2004-11-02
Classification: G06K,G06T

Abstract:
A linear mark detecting method, in which a target image is inputted and a linear mark is detected based on said inputted target image, comprising:a computing step of computing characteristic values including at least a difference in luminance values between an inside and an outside of a linear mark region, edge intensity at an end of said linear mark, and uniformity of luminance in said linear mark, for each point in said inputted target image, an evaluation value attaching step of attaching to each point in said target image an evaluation value indicative of a likelihood of a linear mark characteristic point for detecting said linear mark, based on each of the characteristic values computed in said computing step, and a linear mark image width determining step of determining a width of said linear mark image in the case where a linear mark image exists, for each point in said inputted target image, and wherein: in said computing step of computing a characteristic value of edge intensity at an end of said linear mark, a characteristic value of edge intensity at an end of said linear mark is computed based on the width of said linear mark image, said width being determined in said linear mark image width determining step, for each point in said target image, and in said computing step of computing a characteristic value such a uniformity of luminance in said linear mark, a characteristic value of luminance uniformity in said linear mark is computed based on the width of said linear mark image, for each point in said target image, said width being determined in said linear mark image width determining step in said computing step of computing a characteristic value of a difference in luminance values between the inside and the outside of said linear mark region, a characteristic value of a difference in luminance values between the inside and the outside of said linear mark region is computed based on a position of each point on said target image and said width of said linear mark image; and wherein in said computing step of computing a characteristic value of a difference in luminance values between the inside and the outside of said linear mark region, for each point in said target image, a sum of luminance value is computed for pixels in a relatively close range within a half of the width of said linear mark image, of pixels provided on the same horizontal line, a sum of luminance values is computed for pixels in a relatively long range beyond a half of the width of said linear mark image and within said width, of pixels provided on the same horizontal line, said difference is computed between the sum of luminance values on the closer range and the sum of luminance values on the longer range for each point in said target image, and the characteristic value is computed on said difference in luminance values between the inside and the outside of said linear mark region.