1. A method for optimizing a metrology tool for measuring one or more characteristics of a semiconductor target, comprising: (a) providing a set of specifications and an initial input data for a particular target, wherein the specifications provide limits for characteristics of images that are to be measured by the metrology tool; and (b) automatically optimizing the metrology tool for measuring the particular target so as to meet one or more of the provided specifications without further significant human intervention with respect to the metrology tool.