Development of a High-Performance Stamped Character Reader

A high-performance optical character reader (OCR) capable of reading low-quality stamped alphanumeric characters, on a metal rod, is described in this paper. Reliable and precise recognition is achieved by means of a special scanner and dedicated recognition module. The scanner revolves around the metal rod and detects characters, thus avoiding rotation of the heavy and long rod. Diffused illumination which produces a clear image, a powerful pattern-matching method¿the Multiple Similarity Method (MSM)¿implemented by the recognition module, and the use of adaptive rescan control results in a correct recognition rate of 99.93 percent. One recognition module can process images from up to five different scanners. The processing speed is about 1.5 s/rod. The design and industrial application of the system are discussed.