License Plate Recognition System

This paper presents a novel method of identifying and recognizing license plates, required by an automatic vehicle identification system. The main challenge was the isolation of the car’s license plate, from the digital image acquired by the video system, under different illumination conditions and various angles. Thus, we have established the required preprocessing operations leading to successful plate identification. The string recognition stage is straightforward, after the completion of the character extraction process. Tested on Romanian plate images, the system performance was 93% of correct identified plates and 88.57% of correct recognized characters. Suggestion for further improvements are presented, as well as further related project developpment.

[1]  Hang Joon Kim,et al.  Locating car license plates using neural networks , 1999 .

[2]  Keiichi Yamada,et al.  License plate recognition method for inclined plates outdoors , 1999, Proceedings 1999 International Conference on Information Intelligence and Systems (Cat. No.PR00446).

[3]  Luis Enrique Sucar,et al.  Translation, rotation, and scale-invariant object recognition , 2000, IEEE Trans. Syst. Man Cybern. Part C.

[4]  K. Chamnongthai,et al.  Extraction of car license plate using motor vehicle regulation and character pattern recognition , 1998, IEEE. APCCAS 1998. 1998 IEEE Asia-Pacific Conference on Circuits and Systems. Microelectronics and Integrating Systems. Proceedings (Cat. No.98EX242).

[5]  Paolo Ferragina,et al.  Optical recognition of motor vehicle license plates , 1995 .

[6]  Hans Hegt,et al.  A high performance license plate recognition system , 1998, SMC'98 Conference Proceedings. 1998 IEEE International Conference on Systems, Man, and Cybernetics (Cat. No.98CH36218).

[7]  J. R. Parker,et al.  Gray Level Thresholding in Badly Illuminated Images , 1991, IEEE Trans. Pattern Anal. Mach. Intell..

[8]  Subramaniam Ganesan,et al.  An efficient implementation of the Hough transform for detecting vehicle license plates using DSP'S , 1995, Proceedings Real-Time Technology and Applications Symposium.

[9]  E.D. Di Claudio,et al.  Car plate recognition by neural networks and image processing , 1998, ISCAS '98. Proceedings of the 1998 IEEE International Symposium on Circuits and Systems (Cat. No.98CH36187).

[10]  Milan Sonka,et al.  Image Processing, Analysis and Machine Vision , 1993, Springer US.

[11]  Shyang Chang,et al.  A new criterion for automatic multilevel thresholding , 1995, IEEE Trans. Image Process..

[12]  Gilles F. Houle,et al.  Recognition of license plate images: issues and perspectives , 1999, Proceedings of the Fifth International Conference on Document Analysis and Recognition. ICDAR '99 (Cat. No.PR00318).