A Coarse License Plate Location Method Based on Area Edge Information
A technology of edge information and rough positioning, which is applied in image data processing, instruments, calculations, etc., can solve the problems of high false detection rate and slow rough positioning speed, and achieve fast positioning speed, insensitivity to illumination changes, and small plate size changes. sensitive effect
Active Publication Date: 2017-02-15
ANHUI TSINGLINK INFORMATION TECH
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Generally speaking, the rough positioning speed is slow and the false detection rate is relatively high, so other methods need to be used for further screening
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[0034] Further illustrate the present invention below in conjunction with accompanying drawing.
[0035] Such as figure 1 As shown, a rough license plate location method based on area edge information includes the steps in the following order:
[0036] S1. Collect a number of vehicle images containing license plates, and select one image as the current image for rough license plate location processing.
[0037] S2. Using the edge detection operator to extract the vertical edge map of the current image:
[0038] The method of obtaining the vertical edge map is: take a certain pixel (x, y) in the image as the current pixel, x is the abscissa of the pixel, y is the ordinate of the pixel, and the value of the pixel is recorded as I(x ,y), when calculating the vertical edge index of this pixel, the values of the surrounding 8 pixels should be used, and these 9 pixels form a 3×3 matrix, as shown in formula (1):
[0039]
[0040] The edge detection operator is also a 3×3 ma...
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The invention provides a license plate coarse positioning method based on area edge information. The method includes the steps: extracting a vertical edge graph of an image by the aid of an edge detection operator; gaining an integral graph of the vertical edge graph; sliding a cross template in the vertical edge graph by a certain step length, gaining the ratio of a vertical edge exponential sum of all pixels in a cross template center area at a current position to a vertical edge exponential sum of all pixels in other areas of the cross template by the aid of the integral graph, and adding 1 to the hitting frequency of area pixels with the ratio larger than a certain threshold; performing binarization, dilation operation and communication area analysis for the pixels with the hitting frequency larger than a certain threshold, and performing screening to obtain a license plate coarse positioning result; performing scale conversion for the image, repeating the steps until the size of the image is smaller than a certain threshold after scale conversion, outputting the license plate coarse positioning result, and finishing a processing procedure. The license plate coarse positioning method has the advantages of high positioning speed, insensitivity to illumination variation and license plate size variation and the like.
Description
technical field [0001] The invention relates to the technical field of license plate rough positioning, in particular to a rough license plate positioning method based on area edge information. Background technique [0002] In recent years, cars have become more and more popular in our country. While people enjoy a fast and convenient lifestyle, it has also caused a series of problems, such as traffic congestion, traffic accidents, and vehicle theft. Therefore, efficient and intelligent management of vehicles has become an increasingly urgent social demand. As the core technology to realize various intelligent management applications, the automatic recognition technology of license plate has been extensively studied by many universities, research institutions and enterprises. [0003] The license plate recognition technology is relatively complicated, and can be roughly divided into several parts such as rough positioning of the license plate, rotation correction, fine posi...
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IPC IPC(8): G06T7/00
CPCG06T7/13G06T2207/30252
Inventor 何佳张卡于继梁王小敏
Owner ANHUI TSINGLINK INFORMATION TECH