1. A method of splitting a lithographic pattern into a plurality of sub-patterns, comprising: generating at least one test structure corresponding to one or more structures of interest in the lithographic pattern; varying the at least one test structure through a selected range of dimensions to produce a plurality of varied test structures; determining a plurality of values for an image quality metric for images of the plurality of varied test structures; analyzing the plurality of values to determine ranges of dimensions for which a pattern split would improve the value of the image quality metric; splitting the lithographic pattern into the plurality of sub-patterns of the lithographic pattern in accordance with the determined ranges; and manufacturing a mask corresponding to a first sub-pattern of the plurality of sub-patterns.