A novel license plate location method based on wavelet transform and EMD analysis

作者：Yu, Shouyuan; Li, Baopu; Zhang, Qi; Liu, Changchun^*; Meng, Max Q. -H.

来源：Pattern Recognition, 2015, 48(1): 114-125.

DOI：10.1016/j.patcog.2014.07.027

• License plate location
• Wavelet transform
• EMD analysis
• Hilbert transform

Although various license plate location methods have been proposed in the past decades, their accuracy and ability to deal with different types of license plates still need to be improved. A robust license plate location method can raise the accuracy of the whole license plate recognition procedure. This paper proposes a robust method based on wavelet transform and empirical mode decomposition (EMD) analysis to search for the location of a license plate in an image to deal with some challenging problems in practice such as illumination changes, complex background and perspective change. By applying wavelet transform on a vehicle image and projecting the acquired details of the image, a wave crest that indicates the license plate will be generated. In order to locate the desired wave crest in the nonlinear and non-stationary projection dataset, EMD analysis is applied. Using the reconstructed projection data and the Hilbert transform of intrinsic mode function components, the position of the license plate is detected. Comprehensive experiments show that this method can locate the positions of various types of license plates with a high accuracy of 97.91% and a relatively short running time.

• 出版日期2015-1
• 单位中国科学院; 香港中文大学; 山东大学; 中国科学院深圳先进技术研究院; 深圳大学