A Robust Method for License Plate Detection

License plate detection plays an important role in vehicle license plate recognition for intelligent transport systems. This paper presents a robust method for license plate detection. As we observed, license plate area contains rich corner points’ information. The whole procedure is as follows: (1) Extract the interesting points using Harris corner detector in enhanced car image. (2) Cluster the corner points and apply outlier detection to every cluster. (3) Merge the clusters close to each other and use the gradient information to find the proper block in which the license plate area is enclosed. (4) Train a simple cascade classifier to classify the blocks into two categories: The area possibly containing license plate and those not. (5) Detect the plate region by the rectangle window. Experimental results demonstrate the robustness and the generality of our method.