【作者】 吴炜；

【导师】 何小海；

【作者基本信息】 四川大学 ， 通信与信息系统， 2003， 硕士

【摘要】 本文主要研究基于计算机视觉的车牌识别系统。该系统以图象处理、模式识别等技术为基础，它通过摄像机所拍摄的车辆图象(包含着车牌图象)进行车牌号码的自动识别。该系统有多种应用，如停车场车辆的自动放行、费口自动计费、电子警察监控系统以及移动电子稽查系统、汽车流量分析及统计系统等。本文的主要工作是对车牌识别系统的一些关键技术进行研究。本文新意之处在于：① 在车牌定位中，本文提出了基于边缘检测的二值化和扫描线相结合的车牌定位方法，实验表明该方法能够快速、准确地定位车牌，且抗干扰能力强。② 在车牌切分中，本文提出了一种新的差分二值化算法，并用于车牌图象的二值化。实验证明该算法速度快，分割效果好。③ 在车牌字符识别中，为了提高字符识别的稳定性，本文提出了基于改进的Hausdorff距离字符识别算法。实验表明该算法对字符识别率高，性能稳定。本文的主要内容介绍如下：第一章主要介绍国内外车牌识别系统的发展状况以及车牌识别技术的优点。第二章介绍了车牌识别系统的整体框架以及各个子系统的功能和识别的整体流程。第三章详细介绍车牌识别的车牌定位模块，首先介绍利用车牌不同特征的定位方法，然后介绍本文提出的基于垂直边缘的车牌定位算法和本文提出的垂直边缘提取算法，并且给出定位实验结果。 第四章详细介绍车牌识别的车牌字符切分模块，并且提出一种新的差分二值化算法，并且给出实验结果。 第五章介绍字符识别算法，重点介绍了本文提出的基于改进的Ilansdouff距离字符识别算法。 第六章介绍车牌识别在高速公路收费中的应用的具体应用。更多还原

【Abstract】 A vehicle license plate recognition system(LPR) is presented in the paper, which is based on image processing and pattern recognition. LPR finds its increasingly wide and important application in entrance admission, security, parking control, harbour cargo control ,road trattic control, speed control and so no.Compared with traditional vehicle managing methods , it saves manpower and material resources, realizes scientific standard management and ensures traffic order.The innovations in this thesis are as follows(l)A novel license-plate localization is presented expoiting edge detected binarization and scanline.It is much more robust and faster than traditional methed.(2)A modified binarization is Presented based on mean-differential operator for extractsing characters in the plate. It is more robust and faster than traditional image segmentation metheds. (3)A fast and efficient algorithm is presented, which first thins letter images, then uses improved Hausdorff distance to measure the degree of similarity between templates and letter images. Experiments show that this algorithm is more robust than sample template matching method when recognized characters are slant, deformed or blurred.In Chapter One of this thesis, a vehicle license plate recognition system system is introduced.In Chapter Two are introduced the system architecture andthe functions of subsystem.In Chapter Three, the method of plate locating is first proposed according to different plate features. Then a vertical edge detection method and vertical edge based plate locating method are proposed.In Chapter Four, a character segmentation method is proposed.In Chapter Five, a fast and efficient algorithm is presented, which first thins letter images, then uses improved Hausdorff distance to measure the degree of similarity between templates and letter images.Chapter Six describes how a LPR System is applied in highway electronic toll collection.更多还原