Bar code recovery via the EM algorithm

The ubiquitous supermarket checkout scanner is indeed a well engineered and effective device. There is, nevertheless, demand for better devices. Existing scanners rely on simple and indeed low-cost signal processing to interpret bar code signals. These methods, nevertheless, fundamentally limit label reading and cannot be extended. A new method based on the deterministic EM algorithm is described. First results show a substantial improvement in label reading depth of field, which is an important performance parameter for bar code readers.