A system and methods are provide for modeling the behavior of a lithographic scanner and, more particularly, a system and methods are provide using thresholds of an image profile to characterize through-pitch printing behavior of a lithographic scanner. The method includes running a lithographic model for a target tool and running a lithographic model on the matching tool for a plurality of different settings using lens numerical aperture, numerical aperture of the illuminator and annular ratio of a pattern which is produced by an illuminator. The method then selects the setting that most closely matches the output of the target tool.