Subpixel Image Processing Method in Light Pen Vision Coordinate Measurement

A light-pen portable 3D coordinate vision measurement system is introduced,and a method for picking up the image coordinates of the measured feature points is proposed.Based on the theory of digital image processing and combining with the image characteristics,the practical methods and results of image preprocessing are presented.Applying the radial section scanning method based on gray centroid,the image edges are tested with a subpixel precision.The image coordinates of ellipse spots' centers are picked up using the Least Square fitting method of an ellipsis which is located arbitrarily in a plane,and experimental results show that the prediction of this method can reach 0.1 pixel/subpixel.