17. The non-transitory machine readable medium of claim 15 , wherein the bounding box of the new subset is an intersection of the bounding boxes of all primitive graphic elements already in the new subset.
15. The non-transitory machine readable medium of claim 13 , wherein the set of instructions for identifying overlapping primitive graphic elements as subsets of primitive graphic elements comprises sets of instructions for: selecting a first graphic element in the set and assigning the graphic element to a new subset; assigning a second graphic element in the set to the new subset when a bounding box of the second graphic element overlaps a bounding box of the new subset.