Array codes correcting a cluster of unidirectional errors for two-dimensional matrix symbols [identification technology]

This paper proposes two-dimensional unidirectional clustered error correcting codes suitable for high-density two-dimensional matrix symbols. These codes are capable of correcting unidirectional errors confined in a rectangle having l/sub m/ rows and l/sub n/ columns. Evaluation shows that the proposed codes have smaller number of check bits than the existing codes.