摘要车牌自动识别技术是实现智能交通系统的关键技术，对我国交通事业的发展起着十分重要的作用，进而影响我国的经济发展速度及人们的生活质量。
车牌识别系统运用模式识别、人工智能技术，能够实时准确地自动识别出车牌的数字、字母及汉字字符，进而实现电脑化监控和管理车辆。
一个车牌识别系统的基本硬件配置有照明装置、摄像机、主控机、采集卡等。
而软件则是由具有车牌识别功能的图像分析和处理软件，以及能够具体满足应用需求的后台管理软件组成。
车牌自动识别系统主要分为图像预处理、车牌定位、字符分割和字符识别等主要模块,也包括后续应用程序的开发。
针对不同的模块,本文研究分析了现有的理论算法,并提出了具有实际应用意义的解决方案。
1.在图像预处理模块,因为人眼对于不同颜色分量的敏感度不同,图像灰度化采用加权平均值法；二值化过程中阈值的选取至关重要,本文采用动态自适应阈值法,效果理想；边缘提取利用了拉普拉斯算子;去噪过程采用的是中值滤波方法；2.车牌定位模块包括粗定位和细定位,本文通过分析车牌的尺寸、类型、颜色,得到不同的特征向量,即车牌的几何特征、灰度分布特征、投影特征和字符排列特征等,利用这些特征进行车牌定位；3.在车牌字符分割模块,提出了双向对比垂直投影分割法,该方法基于车牌的垂直投影,能够将字符准确的分割开,利于车牌字符识别: 4.本文对车牌数字和车牌字母及汉字提出了不同的处理方法,数字识别采用投影技术,汉字和字母识别应用BP神经网络技术,兼顾了识别准确率和识别速度;根据上述方法原理,基于MATLAB软件进行程序设计,编制了车牌自动识别软件。
关键字：车牌图像；图像处理；字符分割；BP神经网络AbstractLicense plate recognition technology is to realize the key technology of intelligent transportation system of our country, the development of the cause of traffic plays a very important role, then affects the economic development of our country and speed and people's quality of life. License plate recognition system with pattern recognition, artificial intelligence technology, to real-time accurately recognize the license plate number of automatic, letters and Chinese characters, and achieve computerized monitoring and management vehicles. A license plate recognition system of basic hardware configuration have lighting devices, video camera, master control machine, acquisition card, etc. And software is with license plate identification function by the image analysis and processing software, and can meet the demand of the specific application background management software component. License plate recognition system mainly divided into the image preprocessing, license plate location, character segment and character recognition and other major modules, including the follow-up application development.In view of the different module, this paper analyzed the existing algorithm theory, and puts forward the practical significance of the solution. 1. In the image preprocessing module, for the human eye to different color the sensitivity of the component is different, the image intensity by weighted average method; In the process of binary of the threshold is very important to select is adopted in this paper, dynamic adaptive threshold value method, the effect ideal; Using the Laplace operator edge extraction; Denoising the process is the median filtering method; 2. The license plate localization module contains coarse position and fine positioning, the paper analyzes the license plate size, type, color, get different characteristic vector, namely the geometrical characteristics of the license plate, gray distribution, projection characteristics and characters arrangement characteristics, use these characteristics of the license plate location; 3. In the license plate character segmentation module, and put forward the two-way contrast vertical projection segmentation method, this method is based on the license plate vertical projection, can make the character of accurate separated, beneficial to the license plate character recognition: 4. This article on license plate Numbers and letters and characters put forward different processing methods, number recognition by projection technology, Chinese characters and letters recognition application BP neural network technology, and taking account of the identification accuracy and recognition rate; According to the above method, based on the MATLAB software program design, compiled the license plate recognition software.Keywords License plate image, image processing, character segment, the BP neural network目录摘要............................................. 错误!未定义书签。
