1. A method for correcting a lithography hotspot of a post-routing layout comprising: selecting at least one two-dimensional pattern within a local area of a hotspot; defining at least one change mode to change the at least one two-dimensional pattern, each change mode having an allowable range of amount of change; selecting model cells from a set of optical simulation model cells of aerial image intensity; synthesizing with a computer a corresponding aerial image intensity of the at least one two-dimensional pattern with the selected model cells; optimizing the amount of change of each change mode based on aerial image intensity values of a corresponding aerial image intensity; and comparing aerial image intensity values of each optimized amount of change to obtain a set of optimal change modes for the at least one two-dimensional pattern.