1. A computer-implemented method of selecting a subset of patterns associated with a design, in which the design or a modification of the design is configured to be imaged onto a substrate via a lithographic process, and in which the subset of patterns constitutes a predefined representation of the design, the method comprising the steps of: identifying a set of patterns related to the predefined representation of the design, grouping and/or ranking the set of patterns, defining a threshold related to the grouping and/or ranking, and selecting the subset of patterns from the set of patterns, wherein the subset comprises patterns from the set of patterns above or below the threshold, wherein one or more of the steps are performed by a computer, and wherein the step of identifying a set of patterns comprises the step of calculating diffraction order distributions for the patterns of the design, and wherein the step of grouping and/or ranking the set of patterns comprises grouping the set of patterns into a plurality of groups based on the calculated diffraction order distributions, and wherein the step of selecting the subset of patterns comprises selecting one or more patterns from the plurality of groups as the subset.