Patent ID: 7876952

Claim:
A method for reducing a number of shapes, said method comprising the steps of: forming a first shape pattern; forming a second shape pattern, wherein the second shape pattern consists of all of the first shape pattern and error shapes; extracting the error shapes from the second shape pattern; and a processor of a computer system deriving from a subset of the extracted error shapes at least one environment shape corresponding to each error shape in the subset of the error shapes, said environment shape reflecting a local geometric environment of its corresponding error shape, wherein the deriving step comprises expanding each error shape in the subset to form a corresponding expanded shape; wherein each error shape in the subset has a polygonal shape; wherein expanding a first error shape of the error shapes in the subset comprises outwardly projecting each bounding side of the first error shape by a distance in a direction perpendicular to the bounding side; wherein the distance is a same first distance for each bounding side oriented in a first direction for the first error shape of the error shapes in the subset; wherein the distance is a same second distance for each bounding side oriented in a second direction for the first error shape; wherein the second direction is orthogonal to the first direction; and wherein the same first distance is unequal to the same second distance.