1. A method for constructing a distance histogram for a nearest neighbor classification by distances in feature space between defects and training sample defects, the method comprising the steps of: defining a feature space, determining a training sample defect for each of two classes, for each of defects, measuring a distance in the feature space between the defect and the training sample defect for each of the two classes, normalizing all of the distances for a given defect by dividing each distance for the given defect by the sum of all of the distances for the given defect, and creating a histogram by plotting a chart with the normalized distances versus the number of defects having the distances, placing a threshold bar at the center of the histogram to construct a normal nearest neighbor classifier.