This paper presents an algorithm for extraction (detection) and recognition of license plates in traffic video datasets. For license plate detection, we introduce a method that applies both global edge features and local Haar-like features to construct a cascaded classifier consisting of 6 layers with 160 features. The characters on a license plate image are extracted by a method based on an improved blob detection algorithm for removal of unwanted areas. For license plate recognition (i.e., character recognition), an open source OCR is modified and used. Our proposed system is robust under poor illumination conditions and for moving vehicles. Our overall system is efficient and can be applied in real-time applications. Experimental results are demonstrated using a traffic video.
Zheng, L., He, X., Samali, B., & Yang, L. T. (2013). An Algorithm for Accuracy Enhancement of License Plate Recognition'. Journal of Computer and System Sciences, 79(2), 245-255. https://doi.org/10.1016/j.jcss.2012.05.006