汽车车牌识别系统

车牌定位子系统的设计与实现

摘 要

汽车识别系统是近几年发展起来的计算机视觉和模式识别技术在智能交通领域应用的重要研究课题之一。在车牌自动识别系统中，首先要将车牌从所获取的图像中分割出来，这是进行车牌字符识别的重要步骤，定位准确与否直接影响车牌识别率。MATLAB的车牌定位系统，通过编写MATLAB文件，对各种车辆图像处理方法进行分析、比较,了车牌预处理、车牌粗定位和精定位的方法。采取的是从经过边缘提取后的车辆图像中提取车牌特征进行分析处理从而初步定出车牌的区域，再利用车牌的先验知识和分布特征对车牌区域二值化图像进行处理，从而得到车牌的精确区域并且取得了较好的定位结果。

ENGLISH SUBJECT

ABSTRACT

The subject of the automatic recognition of license plate is one of the most significant subjects that are improved from the connection of computer vision and pattern recognition. In LPSR, the first step is for locating the license plate in the captured image which is very important for character recognition. The recognition correction rate of license plate is governed by accurate degree of license plate location.

Firstly, the paper gives a deep research on the status and technique of the plate license recognition system. On the basis of research, a solution of plate license recognition system is proposed through the software MATLAB,by the M-files several of methods in image manipulation are compared and analyzed. The methods based on edge map and das differential analysis is used in the process of the localization of the license plate, extracting the characteristics of the license plate in the car images after being checked up for the edge, and then analyzing and processing until the??probably area of license plate is extracted，then come out the resolutions for localization of the car plate.

KEY WORDS：imageacquisition，image preprocessing，edge detection，binarization，licence，license plate location

目　录

前　言1

第1章绪 论2

§1.1 课题研究的背景2

§1.2 车牌的特征2

§1.3 国内外车辆牌照识别技术现状3

§1.4车牌识别技术的应用情况4

§1.5 车牌识别技术的发展趋势5

§1.6车牌定位的意义6

第2章MATLAB简介7

§2.1 MATLAB发展历史7

§2.2 MATLAB的语言特点7

第3章图像预处理10

§3.1 灰度变换10

§3.2 图像增强11

§3. 3 图像边缘提取及二值化13

§3. 4 形态学滤波18

第4章 车牌定位21

§4.1 车牌定位的主要方法21

§4.1.1基于直线检测的方法22

§4.1.2 基于阈值化的方法22

§4.1.3 基于灰度边缘检测方法22

§4.1.4 基于彩色图像的车牌定位方法25

§4.2 车牌提取26

结 论30

参考文献31

致 谢33

前　言

随着交通问题的日益严重，智能交通系统应