Thai car license plate recognition using essential-elements-based method

There has been several research on car license plate recognition (LPR). However, the number of research on Thai LPR is limited, besides, most of which are published in Thai. The existing work on Thai LPR have faced problems caused by low- quality license plates and a great number of similar characters that exist in Thai alphabets. Generally, car license plates in Thailand come in different conditions, ranging from new license plates of excellent quality to low-quality ones with screws on or even some paint already peeled off. Thai characters that appear on Thai license plates are also generally shape-complicated. Area-based methods, such as conventional template matching, are ineffective to low-quality or resembling characters. To cope with these problems, this paper presents a new method, which recognizes the character patterns relying only on essential elements of characters. This method lies on the concept that Thai characters can be distinguished by essential elements that form up different shapes. Similar characters are handled by directly focusing on their obvious differences among them. The overall success rate of the proposed method, tested on 300 actual license plates of various qualities, is 85.33%.