ELIMINATION OF SYSTEMATIC-ERROR IN SUBPIXEL ACCURACY CENTROID ESTIMATION

An analysis of the properties of the centroid method for subpixel accuracy image feature location is presented. This method is free of systematic error if the maximum spatial frequency of the image incident on the image sensor is less than the sensor's sampling frequency. This can be achieved by using a lens aperture setting such that the modulation transfer function cut-off frequency due to diffraction is appropriately small. Both simulation and experimental tests of this prediction are presented for the case of the location of the center lines of the images of projected light stripes in a triangulation-based three-dimensional shape measurement system.