A Fast Locating Method of License Plate Based on Clarity and Brightness Evaluation
A positioning method and definition technology, applied in the field of image processing, can solve the problem that the license plate is difficult to be accurately located, cannot be located, etc.
Active Publication Date: 2017-12-26
SUN YAT SEN UNIV
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Problems solved by technology
[0008] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a method for quickly locating license plates based on evaluation of clarity and brightness, which effectively solves the problem that license plates are difficult to locate accurately under different clarity and complex lighting environments. Or can not locate the problem, thus improving the accuracy of license plate location
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[0086] Such as figure 1 As shown, the present embodiment is a kind of license plate rapid location method based on definition and brightness evaluation, specifically comprises the following steps:
[0087] 1. Perform a sharpness evaluation based on noise and sharpness on the input image:
[0088] ① Noise evaluation is to obtain a binary image by performing OTSU threshold processing on the image first, then calculate the proportion of connected regions whose area is smaller than a given threshold, and finally obtain the noise evaluation value through linear transformation. The formula for calculating the noise evaluation value is as follows:
[0089]
[0090] Among them, Comp i is the i-th area, Area i is the area of the i-th region, T area is a given threshold for judging whether the area is too small, a and b are the parameters of the linear transformation.
[0091] ②The sharpness evaluation adopts the point sharpness algorithm, and subtracts 8 neighborhood points f...
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The invention discloses a rapid license-plate positioning method based on definition and luminance evaluation. The rapid license-plate positioning method includes the following steps: 1, carrying out definition evaluation based on noise and sharpness on an input image; 2, carrying out gradient sharpening processing if the definition is insufficient, and carrying out Gaussian fuzzy processing if the definition is excessively high; 3, converting the RGB image into a grey-scale image; 4, carrying out luminance evaluation on the grey-scale image; 5, carrying out illumination unification processing if the luminance is abnormal; 6, extracting the perpendicular edges in the image through a Scharr operator; 7, carrying out local self-adaption threshold processing; 8, filtering the noise through morphological processing, and fusing the perpendicular edges to form a communicated area; 9, carrying out area marking on the communicated area, carrying out screening according to the characteristics of Chinese license plates, and obtaining a license plate area.
Description
technical field [0001] The invention belongs to the field of image processing, in particular to a method for quickly locating a license plate based on definition and brightness evaluation. Background technique [0002] In the intelligent transportation system, the license plate number recognition technology based on digital images has become an indispensable and important part and is widely used in the fields of monitoring and alarming, punishment for violations, access management and highway toll management. License plate location, that is, locating the position of the license plate in the image or video, is the first step in license plate number recognition. Its accuracy directly affects the effect of license plate number recognition, and it is also the most time-consuming step. Therefore, license plate location plays an important role in intelligent transportation systems. [0003] Currently, license plate positioning methods are divided into three categories: [0004] ...
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IPC IPC(8): G06K9/32G06K9/54
Inventor 张永东谭利许跃生
Owner SUN YAT SEN UNIV