Fast license plate locating method

A license plate positioning and fast technology, applied in the field of using top hat transformation and text texture features, can solve the problems of inapplicability to mobile law enforcement, unsatisfactory performance, and high complexity, and achieves reduction of calculation amount, enhanced adaptability, and reduced the effect of interference

Inactive Publication Date: 2008-08-20
BEIHANG UNIV
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Problems solved by technology

When the color information of the license plate is not obvious and the edge information is disturbed, the performance of the existing methods (1)-(4) and (6) is not very ideal, and the method of (5) requires the license plate image to have temporal information
[0004] Chinese patent 02129508.5 discloses an "automatic license plate recognition method" tha

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  • Fast license plate locating method
  • Fast license plate locating method

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Embodiment Construction

[0027] In order to facilitate the description of the present invention, some concepts are introduced first.

[0028] 1. Gray Morphology

[0029] Morphological operations include two-value morphology and gray-scale morphology, which are used for binary images and gray-scale images respectively. For the license plate images processed in this article, the background is complex and the license plate features are relatively weak. Therefore, according to the traditional processing method, first extract the edge features, and then perform morphological operations and connected domain analysis, which cannot get good results. Therefore, to suppress the background of the natural environment where the license plate is located, the present invention uses gray-scale morphology to process the gray-scale image. In gray-scale morphology, it is assumed that f(x, y) and b(x, y) are defined as discrete functions of two-dimensional discrete spaces F and B, where f(x, y) is a gray-scale image, b(x, y)...

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Abstract

A rapid vehicle license plate locating method is provided, which uses top hat transformation and character texture characteristic, and is divided into background subtraction, vehicle license plate region crude location and precision location three steps, specifically comprises: (1) background subtraction, converting obtained color vehicle license plate image into gray image, using top hat transformation to inhibit large-size background object, highlighting vehicle license plate region; (2) crude location phase, calculating image edge map and proceeding binaryzation, morphological dilation and connected components analysis and other operation, obtaining reasonable size vehicle license plate candidate region set; (3) precision location phase, extracting candidate region texture characteristic, using support vector machine classifier to classify candidate vehicle license plate region, thus accurately locating vehicle license plate region. The invention uses the top hat transformation to filter vehicle license plate image, reduces large-size background interference, so that greatly enhances environment adaptation; meanwhile, from crude to fine location method is more efficient, and reduces greatly computing complexity.

Description

Technical field [0001] The invention relates to a license plate positioning method in a natural and complex background in an intelligent transportation system license plate recognition subsystem, in particular to a fast, coarse to precise license plate positioning method using top hat transformation and text texture characteristics. Background technique [0002] At present, the rapid development of my country's economy and transportation has led to a substantial increase in motor vehicles. Monitoring and management of motor vehicles is one of the problems we face. The license plate number is an important mark of a motor vehicle. Motor vehicle license plate number (referred to as license plate) positioning and recognition can be widely used in highway toll stations, parking lot entrances, and government gates, etc., to realize automatic vehicle monitoring and management, and save manpower and material resources. Among them, the license plate location is the key step of license pla...

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Application Information

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IPC IPC(8): G06K9/36G06K9/62
Inventor 朱成军李超池毅涛熊璋
Owner BEIHANG UNIV
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