Young Joon Ahn , Kyu Bum Wee , Man Pyo Hong

The KIPS Transactions:PartB , Vol. 14, No. 2, pp. 81-88, Apr. 2007
10.3745/KIPSTB.2007.14.2.81,   PDF Download:

Abstract

We implement automobile license plates recognition system. These days automobile license plate recognition systems are widely used for tracing stolen cars, managing parking facilities, ticketing speeding cars, and so on. Recognition systems largely consist of three parts: plates extraction, segments extraction, and segment recognition. For plates extraction, we measure the degree of inclination of a plate. We use filters that extract only the horizontal components of the front of an automobile to measure the degree of inclination. For segments extraction, we trace the change of the number of blocks that consist solely of foreground pixels or background pixels as the horizontal scanning line moves along upward. For recognition of each individual letter or digit, we devise a variant of template matching method, called comparative template matching. Through experiments we show that comparative template matching is less prone to be misled by noises and exhibits higher performance compared to the traditional methods of template matching or histogram-based recognition.

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