License plate image binaryzation method based on Laplacian extension operator

A license plate image, binarization technology, applied in computing, computer parts, instruments, etc., can solve the problems of character breakage, artifact phenomenon, segmentation and recognition failure, to improve the binarization effect and preserve the integrity. Effect

Inactive Publication Date: 2018-04-13
SHANGHAI SEARI INTELLIGENT SYST CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is: when the traditional method based on grayscale binarization processes license plate images obtained under complex lighting conditions, character breaks and artifacts will occur, resulting in segmentation and recognition failures

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  • License plate image binaryzation method based on Laplacian extension operator
  • License plate image binaryzation method based on Laplacian extension operator
  • License plate image binaryzation method based on Laplacian extension operator

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Embodiment Construction

[0026] In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

[0027] The present invention provides a kind of license plate image binarization method based on Laplacian expansion operator, comprises the following steps:

[0028] Step 1. Based on the 5×5 field Laplacian extension operator, the grayscale image of the license plate is convoluted to obtain the positive and negative edge distribution features. In this embodiment, the Laplacian extension operator is Templt[25]:

[0029] Templt[25]={1, 1, 1, 1, 1,

[0030] 1, 1, -4, 1, 1,

[0031] 1, -4, -4, -4, 1,

[0032] 1, 1, -4, 1, 1,

[0033] 1,1,1,1,1};

[0034] Step 2. Use the maximum inter-class variance method to obtain the threshold T1 of the threshold positive edge distribution feature and the threshold T2 of the negative edge distribution feature. By judging the relationship between the pixel value of each point of the license pla...

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Abstract

The invention relates to a license plate image binaryzation method based on a Laplacian extension operator, which is characterized by including the following steps: carrying out convolution operationon a license plate gray image by using a Laplacian extension operator, and acquiring positive and negative edge distribution features; acquiring a threshold T1 of positive edge distribution feature and a threshold T2 of negative edge distribution feature through an OTSU method, and generating a ternary image; and distinguishing between the characters and background of the license plate according to the pixel values of the points of the ternary image, and obtaining a binary image. The defects of the application of the traditional method based on gray binaryzation in special scenes are overcome.For a license plate image with shadow, local overexposure or the like, the integrity of the strokes can be fully retained, and the binaryzation effect of the license plate image can be improved.

Description

technical field [0001] The invention relates to a method for binarizing a license plate image, which is used for automatic identification of the license plate. Background technique [0002] In the license plate recognition system, usually the license plate character segmentation algorithm mainly uses binary images for segmentation processing. There are many existing segmentation methods, such as projection method, connected domain extraction method and clustering method, but the prerequisite is that the quality of the binary image to be processed is clear, otherwise it is easy to cause segmentation errors or broken strokes. [0003] At present, the binarization methods based on gray threshold segmentation are basically divided into the following three categories: local threshold, global threshold and dynamic threshold, each of which has advantages and disadvantages. Using the binarization algorithm based on gray threshold segmentation, when processing license plate images a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/38G06K9/34
CPCG06V10/26G06V10/28G06V20/625
Inventor 施云龙舒翔龙王成龙荀玲玉何玉娇
Owner SHANGHAI SEARI INTELLIGENT SYST CO LTD
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