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http://dx.doi.org/10.5909/JBE.2019.24.5.713

Robust Motorbike License Plate Detection and Recognition using Image Warping based on YOLOv2  

Dang, Xuan-Truong (Department of Electronics Engineering, Korea Polytechnic University)
Kim, Eung-Tae (Department of Electronics Engineering, Korea Polytechnic University)
Publication Information
Journal of Broadcast Engineering / v.24, no.5, 2019 , pp. 713-725 More about this Journal
Abstract
Automatic License Plate Recognition (ALPR) is a technology required for many applications such as Intelligent Transportation Systems and Video Surveillance Systems. Most of the studies have studied were about the detection and recognition of license plates on cars, and there is very little about detecting and recognizing license plates on motorbikes. In the case of a car, the license plate is located at the front or rear center of the vehicle and is a straight or slightly sloped license plate. Also, the background of the license plate is mainly monochromatic, and license plate detection and recognition process is less complicated. However since the motorbike is parked by using a kickstand, it is inclined at various angles when parked, so the process of recognizing characters on the motorbike license plate is more complicated. In this paper, we have developed a 2-stage YOLOv2 algorithm to detect the area of a license plate after detection of a motorbike area in order to improve the recognition accuracy of license plate for motorbike data set parked at various angles. In order to increase the detection rate, the size and number of the anchor boxes were adjusted according to the characteristics of the motorbike and license plate. Image warping algorithms were applied after detecting tilted license plates. As a result of simulating the license plate character recognition process, the proposed method had the recognition rate of license plate of 80.23% compared to the recognition rate of the conventional method(YOLOv2 without image warping) of 47.74%. Therefore, the proposed method can increase the recognition of tilted motorbike license plate character by using the adjustment of anchor boxes and the image warping which fit the motorbike license plate.
Keywords
Motorbike License Plate; License Plate Detection; Image Warping; YOLOv2;
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Times Cited By KSCI : 1  (Citation Analysis)
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