基于数字图像处理的车牌识别系统设计

基于数字图像处理的车牌识别系统

摘要

汽车的数量的日渐增多，目前，城市的交通情况受到了人们极大的关注，怎样进行有效的交通管理便成为了人们关注的重点。针对此问题，人们利用新的科学技术，不断努力研发出了各种交通道路监视、管理系统等。这些系统，通过使用车辆检测装置对过往的车辆进行检测，对相关的交通数据进行提取，是为了达到监控、管理和指挥交通的目的。车牌识别系统现已经在高速公路、城市十字交通路口和停车场等项目中拥有着不可替代的地位。

本设计使用数字图像处理方法，来解决车牌识别的问题。通过数字图像处理技术，对原始汽车图像进行处理，通过对图像的预处理、车牌定位、字符分割和字符识别四部分进行处理，最终得到车牌识别的字符。本设计的图像预处理是把汽车图像通过灰度化、二值化、边缘检测等操作，转变成易于定位的图像；车牌定位是首先利用边缘检测和形态学处理对车牌进行预定位，之后利用Radon变换倾斜矫正车牌，最后进行精确定位剪切车牌；字符分割是通过投影法进行字符的切分，然后利用双线性插值算法对字符进行归一化的处理；字符识别是将归一化之后的字符和建立好的模板字符库进行逐一比对，通过找差值来实现字符的匹配。本设计的算法是在MATLAB2017b上进行了仿真和测试，可以较好的识别出车牌号码。

关键词：图像处理，车牌识别，边缘检测，MATLAB

License plate recognition system based on digital image

processing

Abstract

The number of cars is increasing day by day. At present, people pay great attention to the traffic situation of the city. How to carry out effective traffic management has become the focus of people's attention. In response to this problem, people have made continuous efforts to develop various traffic road monitoring and management systems by using new science and technology. These systems, through the use of vehicle detection devices to detect the passing vehicles, extract the relevant traffic data, in order to achieve the purpose of monitoring, management and command of traffic. License plate recognition system now has an irreplaceable position in expressway, urban cross traffic intersection and parking lot projects.

This design uses digital image processing method to solve the problem of license plate recognition. Through the digital image processing technology, the original vehicle image is processed. Through the image preprocessing, license plate positioning, character segmentation and character recognition, the characters of license plate recognition are finally obtained. The image preprocessing of this design is to transform the automobile image into the image which is easy to locate through the operation of grayscale, binarization, edge detection, etc.; the license plate location is to use the edge detection and morphological processing to pre locate the license plate, then use Radon transform to tilt and correct the license plate, and finally carry out the accurate location and cutting of the license plate; the character segmentation is to cut the characters through the projection method Then, the bilinear interpolation algorithm is used to normalize the characters. Character recognition is to compare the normalized characters with the established template character library one by one, and to match the characters by finding the difference. The algorithm of this design is simulated and tested on matlab2017b, which can recognize the license plate number better.

Keywords: Image processing, license plate recognition, edge detection, MATLAB