1. A method of obtaining short-range flare model parameters representing a short-range flare which degrades a contrast of an image generated by a lithography tool, comprising the steps of: measuring short-range flare from the image to obtain measured short-range flare data; performing a simulation based on short-range flare model parameters to obtain simulated short-range flare data; comparing the simulated short-range flare data with the measured short range flare data; determining whether the short-range flare model parameters used in the simulation is appropriate based on the comparison result; and optimizing the short-range flare model parameters according to the measured short-range data and the simulated short-range flare data if the short-range flare model parameters used for the simulation is not appropriate.