A method including modeling high resolution patterning error information of a patterning process involving a patterning device in a patterning system using an error mathematical model, modeling a correction of the patterning error that can be made by a patterning device modification tool using a correction mathematical model, the correction mathematical model having substantially the same resolution as the error mathematical model, and determining modification information for modifying the patterning device using the patterning device modification tool by applying the correction mathematical model to the patterning error information modeled by the error mathematical model.