Development of a container identification mark recognition system

This paper reports the development of a container identification mark or number recognition system designed for application to a container terminal. The recognition system recognizes the number or mark on the back surface of a container in an outdoor environment by photographing the mark by a camera system installed on the container gate. Containers in many cases differ in color as well as in layout depending on their owners; the layouts commonly contain one to four horizontal columns or rows of writing or more rarely vertical rows of writing. The container number recognition system is constructed from an illumination intensity sensor and illumination system for handling the outdoor illumination changes, a shutter speed control device, and devices such as filters for handling various container colors. In addition, the proposed system uses a character recognition scheme based on a dynamic design method for recognizing differing character string layouts in container marks or numbers. Field tests have been conducted to obtain a recognition rate of 92.8% for all data, a recognition rate of 97.9% for effective or appropriate data excluding data outside the field of vision, and an average recognition speed of less than 2 seconds.