A Theory for Multiresolution Signal Decomposition: The Wavelet Representation
IEEE Transactions on Pattern Analysis and Machine Intelligence
Digital Image Processing
Fingerprint Matching Based on Directional Image Constructed Using Expanded Haar Wavelet Transform
CGIV '04 Proceedings of the International Conference on Computer Graphics, Imaging and Visualization
Extraction and Recognition of License Plates of Motorcycles and Vehicles on Highways
ICPR '04 Proceedings of the Pattern Recognition, 17th International Conference on (ICPR'04) Volume 4 - Volume 04
Color Prior Knowledge-Based License Plate Location Algorithm
DMAMH '07 Proceedings of the Second Workshop on Digital Media and its Application in Museum & Heritage
Vehicle License Plate Location Method Based-on Wavelet Transform
CSO '09 Proceedings of the 2009 International Joint Conference on Computational Sciences and Optimization - Volume 02
License Plate Recognition From Still Images and Video Sequences: A Survey
IEEE Transactions on Intelligent Transportation Systems
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In a vehicle license plate extraction system, plate region detection is the key step before the final recognition. This paper presents a license plate detection algorithm from complex background based on gradient analysis and prolonged haar wavelet transform. First the license plate region is approximately detected using gradient analysis and top hat transformation of horizontal projection by choosing appropriate threshold. Accurate detection is obtained using multi resolution feature of candidates by using prolonged haar wavelet transformation. Due to the limitation of haar wavelet, we use expanded version of it to get better location of license plate without using morphological operations. Finally, accurate vertical position of license plate is detected and license plate is extracted from image. The test images taken from various scenes were employed, including diverse angles, different lightening conditions. The experiments shows that proposed method can quickly and correctly detect the region of license plate.