Multiple Chinese Vehicle License Plate Localization in Complex Scenes

License plate localization is an essential part of automated vehicle license plate recognition (ALPR). This paper proposes a two-step approach of the vehicle license plate (LP) localization which includes a novel attempt for LP detection and a new method for LP skew correction. The proposed approach begins with detecting the LP region while classifying the LP type in the image using single shot multi-box detector (SSD) and then further precisely determining the LP corner points in detected region by fitting LP borderlines according to the character contours based on the multi-level thresholding binarization. The experiment evaluated the performance of the proposed method on 600 vehicle images (~800*800) captured under realistic complex environment. The result shows that LPs in 579 images can be localized exactly (96.50%accuracy) and processing speed is up to 27 FPS on average.

[1]  Hsi-Jian Lee,et al.  Extraction and recognition of license plates of motorcycles and vehicles on highways , 2004, Proceedings of the 17th International Conference on Pattern Recognition, 2004. ICPR 2004..

[2]  Kang-Hyun Jo,et al.  A VEHICLE LICENSE PLATE DETECTION METHOD FOR INTELLIGENT TRANSPORTATION SYSTEM APPLICATIONS , 2009, Cybern. Syst..

[3]  Changping Liu,et al.  A fast license plate extraction method on complex background , 2003, Proceedings of the 2003 IEEE International Conference on Intelligent Transportation Systems.

[4]  Bo Chen,et al.  MobileNets: Efficient Convolutional Neural Networks for Mobile Vision Applications , 2017, ArXiv.

[5]  Wael Badawy,et al.  Automatic License Plate Recognition (ALPR): A State-of-the-Art Review , 2013, IEEE Transactions on Circuits and Systems for Video Technology.

[6]  Wei Liu,et al.  SSD: Single Shot MultiBox Detector , 2015, ECCV.

[7]  Jin Liu,et al.  Robust vehicle license plate localization using To-MACH filter , 2010, 2010 5th International Conference on Computer Science & Education.

[8]  Kang-Hyun Jo,et al.  Vehicle License Plate Detection Method Based on Sliding Concentric Windows and Histogram , 2009, J. Comput..

[9]  Duong Anh Duc,et al.  Combining Hough transform and contour algorithm for detecting vehicles' license-plates , 2004, Proceedings of 2004 International Symposium on Intelligent Multimedia, Video and Speech Processing, 2004..

[10]  Changping Liu,et al.  A hybrid License Plate Extraction Method Based On Edge Statistics and Morphology , 2004, ICPR.

[11]  Pietro Perona,et al.  Microsoft COCO: Common Objects in Context , 2014, ECCV.

[12]  Fa-Liang Chang,et al.  Automatic License-Plate Location and Recognition Based on Feature Salience , 2009, IEEE Transactions on Vehicular Technology.

[13]  Wei Pan,et al.  Fuzzy-based algorithm for color recognition of license plates , 2008, Pattern Recognit. Lett..

[14]  Ioannis Anagnostopoulos,et al.  A License Plate-Recognition Algorithm for Intelligent Transportation System Applications , 2006, IEEE Transactions on Intelligent Transportation Systems.