Recognition of vehicle license plates from a video sequence

I. Chen Tsai*, Jui Chen Wu, Jun-Wei Hsieh, Yung Sheng Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


This paper proposes a robust system to recognize vehicle license plate by multi-frames learning. To fast locate the position of a license plate, we adopt a morphology-based method to extract important contrast features as filters to find all possible license plate candidates after calculating motion energy from video frames. The contrast feature is robust to lighting changes and invariant to different transformations like image scaling, translation, and skewing. Due to noise, many impossible license regions may be extracted. Hence, a Support Vector Machine (SVM) algorithm is adopted for verifying license plate regions. After locating license plate, the scheme of shape contexts is used to recognize the characters in license plate. To improve the correct rate of recognition, the verifying technique of multi-frames is further involved in our approach. Experimental results show that the proposed method is robust for the recognition of license plate.

Original languageEnglish
Article number04
JournalIAENG International Journal of Computer Science
Issue number1
StatePublished - Feb 2009


  • License plate recognition
  • Morphology-based method
  • Shape contexts
  • Support Vector Machine


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