An OCR system for matching wire harnesses and connectors facilitates precise registration of wire number strings, uses geometric modeling for character recognition, and restricts searches by region and character to ensure speed and accuracy. A string location algorithm is used to search for and identify the location of the beginning of a wire number string. The horizontal edges of the wire in the image are located, a diameter of the wire is determined, light intensity is confirmed, and the first character is found. The resulting coordinate is used by the algorithm for character definition. Geometric shapes are used for identification in order to overcome twisted wires, poorly printed markings, ink color variations, and contacting characters.