Embodiments of a method include: converting at least one image of a printed mask to a plurality of representative contours, each corresponding to mask patterns in the printed mask; determining whether the printed mask includes a printing defect based on whether the plurality of representative contours violates a set of contour tolerances for the printed mask; in response to at least one of plurality of representative contours violating at least one of the set of contour tolerances: identifying a location where a representative contour violates the at least one of the set of contour tolerances, and generating an instruction to adjust a layout for the printed mask, based on the violating of the at least one of the set of contour tolerances; and in response to none of the plurality of representative contours violating the set of contour tolerances, flagging a layout for the printed mask as compliant.