Method and apparatus for subpixel accuracy there determination of the position of one edge of a marker structure in a plurality of receiving pixels receiving the marker structure having

摘要

A method for subpixel accuracy there determination of the position of one edge of a marker structure in a receptacle having a plurality of pixels to receive the marker structure, in whicha) from the receiving pixels along a spatial coordinate a discrete intensity profile of the edge with a plurality of profile pixels is derived,b) a continuous profile function of the edge as a function of the location coordinate based on the profile of pixels is calculated,c) an intensity threshold value is determined, which defines the edge positions,d) of said plurality of profile pixels a plurality of adjacent profile pixels whose intensity values lie in an area in which is also the intensity threshold value, be determined as evaluation pixel,e) on the basis of the evaluation of pixels, a continuous intensity curve as a function of the location coordinate for the region is calculated,f) as the first spatial coordinate the spatial coordinate is determined, on which the intensity value of the continuous intensity curve of step e) the threshold value corresponds to,g) of the distance between the first position coordinate and the spatial coordinate of the evaluation of the pixels of step d), whose intensity value of all evaluation pixels at the closest to the threshold value is ascertained,h) of the distance determined is compared with a predetermined maximum value and, if the distance is larger than the maximum value is, the method with step i) is continued, and if the distance is not greater than the maximum value is, the method is continued with step k),i) a displacement is effected so that the profile function of step b) is present as shifted profile function, the relative to the pixel coordinates as a function of the distance determined in step g) or in steps g) is shifted distances determined, and the intensity values of the profile, in each case, the pixel at the corresponding pixel coordinate present intensity value of the offset profile function is then fixed and the method comprising the steps of d) – h) is continued,k) the edge positions in the receptacle from all of the subpixel accuracy, in step g) is determined at intervals determined.