Journal of KIISE:Software and Applications (한국정보과학회논문지:소프트웨어및응용)

Korean Institute of Information Scientists and Engineers (한국정보과학회)
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Detection of Various Sized Car Number Plates using Edge-based Region Growing

에지 기반 영역확장 기법을 이용한 다양한 크기의 번호판 검출

  • 김재도 (숭실대학교 전자공학과) ;
  • 한영준 (숭실대학교 정보통신전자공학부) ;
  • 한헌수 (숭실대학교 정보통신전자공학부)
  • Published : 2009.02.15
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Abstract

Conventional approaches for car number plate detection have dealt with those input images having similar sizes and simple background acquired under well organized environment. Thus their performance get reduced when input images include number plates with different sizes and when they are acquired under different lighting conditions. To solve these problem, this paper proposes a new scheme that uses the geometrical features of number plates and their topological information with reference to other features of the car. In the first step, those edges constructing a rectangle are detected and several pixels neighboring those edges are selected as the seed pixels for region growing. For region growing, color and intensity are used as the features, and the result regions are merged to construct the candidate for a number plate if their features are within a certain boundary. Once the candidates for the number plates are generated then their topological relations with other parts of the car such as lights are tested to finally determine the number plate region. The experimental results have shown that the proposed method can be used even for detecting small size number plates where characters are not visible.

기존의 번호판 검출 기법들은 대부분 일정한 거리와 방향에서 촬영되어 번호판의 크기가 유사하고, 배경이 단순한 차량 전면 영상에 적용되는 한계를 가지고 있어서 번호판의 위치가 변하거나 조명 혹은 크기의 변화에 매우 취약하다. 본 논문에서는 이러한 기존 기법들의 문제점들을 극복하기 위하여 에지기반 영역확장 기법을 사용하는 번호판 검출기법을 제안한다. 1단계에서는 입력영상에서 예지영상을 얻고 번호판의 기하학적 특성을 갖는 에지 영역들을 검출하여 이들을 번호판 검색영역으로 정한다. 검색영역의 에지들을 기반으로 주변의 화소들을 색상을 기반으로 영역확장을 통해 분할하여 번호판의 기하학적 특성을 만족하는 영역들을 번호판 후보영역으로 정한다. 후보영역들은 자동차의 조명등과 같은 구조물과의 위상특성을 고려하여 최종결정한다. 본 논문에서 제안하는 기법은 번호판의 문자가 검출되지 않는 경우에도 번호판 위치의 검출이 가능하고 특히 작은 크기의 번호판 검출에 유리하며, 크기와 상관없이 번호판을 검출할 수 있음을 실험을 통해 입증하였다.

Keywords

References

  1. B. Hongliang, L. Changping, 'A hybrid license plate extraction method based on edge statistics and morphology,' 17th International Conference On Pattern Recognition(ICPR'04), 2:831-834, 2004 https://doi.org/10.1109/ICPR.2004.1334387
  2. M. Sarfraz, M. J. Ahmed, S. A. Ghazi, 'Saudi arabian license plate recognition system,' Proceedings of the 2003 International Conference on Geometric Modeling and Graphics(GMAG'03), pp. 36-41, 2003 https://doi.org/10.1109/GMAG.2003.1219663
  3. D. K. H. Lee, D. Kim and S. Bamg, 'Real-time automatic vehicle management system using vehicle tracking and car plate number identification,' in Proc. Int'l Conf. on Multimedia and Expo, Vol.2, pp. 353-356, July 2003 https://doi.org/10.1109/ICME.2003.1221626
  4. K. L. T.H. Wang, F.C. Ni and Y. Chen, 'Robust license plate recognition based on dynamic projection warping,' in IEEE International Conference on Networking, Sensing and Control, Vol.2, pp. 784-788, Mar. 2004 https://doi.org/10.1109/ICNSC.2004.1297046
  5. Tran Duc Duan, Duong Anh Duc and Tran LeHong Du, 'Combining Hough transform and contour algorithm for detecting vehicles' licenseplate,' International Symposium on Intelligent Multimedia, Video and Speech Processing, pp. 747-750, 2004
  6. V. Shapiro, D. Dimov, S. Bonchev, V. Velichkov, and G. Gluhchev. Adaptive license plate image extraction. International Conference on Computer Systems and Technologies, 2003 https://doi.org/10.1145/1050330.1050364
  7. S. Kim, D. Kim, Y. Ryu and G. Kim, 'A Robust License-plate Exeaction Method under Complex Image Conditions,' the 16th Intemational Conference on Pattem Recognition (16th ICPR), Quebec, Canada, pp. 216-219, 2002
  8. Wei-gang Zhu, Guo-jiang Hou and Xing Jia, 'A study of locating vehicle license plate based on color feature and mathematical morphology,' Signal Processing, pp. 748-751, 2002
  9. Hongliang Bai, Junmin Zhu, Changping Liu, 'A Fast License Plate Extraction Method on Complex Background,' the 2003 IEEE International Conference on Intelligent Transportation System,' pp. 985-987, 2003
  10. Jun-Wei Hsieh, Shih-Hao Yu, Yung-Sheng Chen, 'Morphology-based License Plate Detection from Complex Scenes,' 16th International Conference On Pattern Recognition, pp. 176-179, 2002
  11. Fernando Martin, Maite Garcia, Jose Luis Alba, 'New Methods For Automatic Reading of VLP’s (Vehicle License Plates),' Signal Processing Patten Recognition and application, 2002
  12. Feng Yang and Zheng Ma, 'Vehicle License Plate location Based on Histogramming and Mathematical Morphology,' 4th IEEE Workshop on Automatic Identification Advanced Technologies, pp. 89-94, 2005
  13. Shyang-Lih Chang, Li-Shien Chen, Yun-Chung Chung, and Sei-Wan Chen, 'Automatic License Plate Recognition,' in Proc. IEEE Int. Conf Intelligent Transportation Systems, March 2004
  14. X. Shi,W. Zhao, and Y. Shen, 'Automatic license plate recognition system based on color image processing,' in Lecture Notes on Computer Science, vol. 3483, O. Gervasi et al., Eds. New York: Springer-Verlag, pp. 1159-1168, 2005
  15. Hamid Mahini, Shohreh Kasaei, Faezeh Dorri, Fatemeh Dorri., 'An Efficient Features.Based License Plate Localization Method,' in Proc. IEEE Int.Conf Pattern Recognition ICPR 2006
  16. Canny, J., 'A Computational Approach to Edge Detection,' IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. PAMI-8. pp. 679-698, 1986
  17. A. K. Jai, Fundamentals of Digital Image Processing, Prentice-Hall, 1989
  18. Yanamura, Y., Goto, M., Nishiyama, D., 'Extraction and tracking of the license plate using Hough transform and voted block matching,' Intelligent Vehicles Symposium 2003, Proceedings. IEEE, pp. 243-246
  19. Lee Hyun-Chan, 'Design and Implementation of Efficient Plate Number Region Detecting System in Vehicle Number Plate Image,' Journal of the Korea society of computer and information, Vol.10 No.5 = No.37, 2005, pp. 87-94