System, a method and a computer program product for size estimation

A computerized method for estimating a size of a nanometric part of an inspected article, the method including: (a) acquiring inspection results generated by processing an inspection image which was generated by collecting signals arriving from a portion of the article which includes the part by an inspection system; (b) fitting to the inspection results an approximation function from a group of functions which is related to a response pattern of the inspection system; and (c) determining an estimated size of the part, based on at least one parameter of the approximation function.