1. A method of determining an average contour of a patterned feature of a wafer, the method comprising: providing a reference contour corresponding to the patterned feature on the wafer; providing a plurality of images of the patterned feature; extracting from the plurality of images a plurality of extracted contours that represent the patterned feature; eliminating flyers from the plurality of extracted contours; and generating the average contour of the patterned feature based on the extracted contours remaining after elimination of the flyers.