In a method for identifying cells, line graphics are converted into vectors (12) having a canonical form without vector overlaps or crossings. Connecting vectors (22, 24, 26, 30, 32) are associated, including (i) forking vectors (22) having common starting points, and (ii) meeting vectors (24) having common ending points. A set of vectors is identified including at least two forking vectors and two meeting vectors cooperatively defining a cell.