基于彩色像素统计与新型模板匹配的车牌识别系统

提出一种新型的车牌定位方法与字符识别方法。在整个车辆图片中,车牌区域具有对比度高,形状规整等特点,运用彩色像素统计法直接对车辆图像进行车牌定位,对提取的车牌进行滤波和锐化,抑制噪声对车牌区域的干扰,最后对类间距离差别较大的字符类型制作多个模板,来达到模板的更有效匹配。结果表明,与传统方法相比,该方法对车牌定位、字符的提取和识别具有精确度高、运算时间少且鲁棒性好的优势。     

基于灰度跳变与字符间隔模式的车牌定位方法研究

车牌定位是车牌自动识别的第一步,而如何考虑光照影响是车牌定位是否成功的关键;通过深入分析不同的车牌图像,提出一种基于灰度跳变与字符间隔模式的车牌定位方法;首先,针对不同光照条件下采集到的车牌图像明暗度的不同,利用多阈值处理方法得到车牌信息不丢失的、最佳的二值图像,然后,在其二值图像中首先利用灰度跳变定位车牌的上下边界,接着对字符垂直投影后的宽度进行统一的调整并以固定的字符间隔特征定位车牌的左右边界,从而完成车牌定位;最后,通过实验验证了该方法的有效性。     

车辆牌照识别系统的设计

利用数字图像处理技术以及神经网络技术对车牌识别系统进行研究。首先从采集的牌照图片中进行车牌定位,车牌字符分割,字符特征提取,最后送入BP神经网络进行识别。     

机械式冲床停上死点位置的控制策略设计与实现

车牌定位是车牌自动识别的第一步,而如何考虑当照影响是车牌定位是否成功的关键。本文提出了一种考虑不同光照条件的车牌定位方法,首先,针对不同光照条件下采集到的车牌图像明暗度的不同,利用多阈值处理方法得到车牌信息不丢失的、最佳的二值图像,然后,在其二值图像中首先利用灰度跳变定位车牌的上下边界,接着对字符垂直投影后的宽度进行统一的调整并以固定的字符间隔特征定位车牌的左右边界,从而完成车牌定位。最后,通过实验验证了该方法的有效性。     

实时车牌定位模块IP Core的研究与设计

车牌定位是车牌识别系统需要解决的首要问题。基于FPGA的硬件特点,提出了一种简单、有效的车牌定位算法。在车牌区域图像的预处理阶段,提出了一种新的基于色彩分量的灰度化方法,该方法不仅可以消除小型民用车车牌图片的背景和车身信息,还可以较好的保留车牌区域信息,从而降低定位难度,简化定位步骤,提高小型民用车车牌定位的效率。并设计了一种实时车牌定位模块的软核IP,该IP Core通过了代码覆盖率和功能覆盖率的测试。实际工程项目测试表明,该IP Core定位准确、反应速度快。     

基于LabVIEW图像法车牌智能识别系统

车辆牌照自动识别是实现交通管理智能化的重要环节,设计中利用图像采集卡对经过的车辆车牌进行图像采集并传送至计算机,采用美国NI公司LabVIEW软件,实现图像预处理、图像去噪以及图像增强等功能;然后根据车牌颜色特征对其准确定位,采用阈值法分割车牌字符;最后由OCR函数来识别字符,识别结果保存至相应数据中,可以进行相应的违章、违规智能交通管理,经实验该系统成功实现车牌识别识别率达99%。     

基于OpenCV的车牌图像定位

现有的车牌定位方法几乎都需要先对白天夜晚的场景进行分类,在图像中存在其他灰度剧烈变化区域时,这种场景分类容易影响到车牌定位的准确率;为了对获取到的车辆图像进行准确地定位,提出了一种改进的灰度跳变车牌定位算法,首先加入了光照补偿,使得不需要对白天和晚上的场景进行分类;然后进行了长竖线的噪声去除,可以在背景比较复杂的情况下准确定位车牌;并对精确定位出的车牌进行边框的去除,有利于下一步的字符分割;另外,对OpenCV计算机视觉库的库函数的利用,算法的复杂度得到了简化,从而更好地满足了车牌识别系统的实时性;通过对出入口处采集到的分辨率为704×576的300张图片进行测试,定位率高于95%,对白天和夜晚获取的图像有很好的适应性,满足设计要求。     

基于FPGA和DSP的车牌识别系统的研究

摘要：本文介绍了一种以DSP和FPGA为核心的车牌识别系统的设计方案,利用FPGA控制车牌图像数据的采集,经过图像格式转换之后传送到DSP中,进行车牌区域定位、字符分割、车牌识别等操作,最后将识别结果传送到LCD中显示。系统采用CCS（Code Composer Studio）集成开发环境,利用VC 语言编程实现车牌识别算法。通过嵌入式机器视觉库EMCV实现识别算法在DSP中的移植,并在LCD上创建工作窗口显示识别结果。实验结果表明该车牌识别系统的设计方案识别结果准确,功能稳定可靠。     

基于智能手持设备的车牌识别系统研究

以交警能更加快捷方便地稽查运营车辆为目的,借助最新的移动互联网技术,分析并研究了多种计算机视觉算法。提出了一种基于K均值聚类（K-means）的车牌定位技术,通过颜色的聚类分析来确定车牌区域,定位车牌。又应用垂直投影技术和模板匹配法来分割和识别车牌字符,利用SQlite开发了具有存储车牌字符信息功能的数据库。在此基础上,研制了一套基于智能手持设备的车牌识别系统。功能测试表明,该系统具有良好的性能,能够较好地识别出车牌信息。     

一种新型自适应环境光照的车牌定位算法

为解决在不同光照环境下车牌的适应性定位问题,同时解决基于颜色定位的方法普遍存在的车身颜色与车牌颜色相近,以至于难以区分的问题,分析了不同光照下的车牌图像在HSV空间的分布特性与图像亮度等参数关系,结合车牌的混色分布特点、RGB与HSV空间变量转换关系,提出了一种可直接对RGB空间进行处理、能适应光照环境的快速车牌定位算法;实验结果表明,提出的定位算法对光照不足、环境光不均匀等复杂条件下获取的蓝白车牌图像具有很高的定位可靠性。     

Self-adaptive model of texture-based target location for intelligent transportation system applications

In this paper, three shortages: full-enhancement mechanism, invariable texture extraction mechanism, and lack of robust enhancement methods, that are always neglected in some tasks based on texture-based target location for Intelligent Transportation System applications (ITS) are introduced. To cover these shortages, a self-adaptive model for texture-based target location is established. It is mainly composed of self-adaptive enhancement mechanism, self-adaptive texture extraction mechanism, and graying enhancement. Also, feedback evaluation strategy for design of texture extraction modes, needed by self-adaptive texture extraction mechanism, is provided. And then, an algorithm of license plate location is designed to evaluate effectiveness of this model. 338 license plate images from natural scenes were applied to test graying enhancement and self-adaptive location. Results of enhancement experiment indicate that graying enhancement is robust in purposiveness, real-time performance, and empirical parameter independence, simultaneously. Further, Results of location experiment demonstrate that not only a sound algorithm of license plate location with high success rate (96.1%) and low average execution time (52 ms) is given but also the effectiveness of the two self-adaptive mechanisms in the proposed model are validated.     

License plate detection using gradient information and cascade detectors

In this paper, we propose a license plate detection method based on the gradient information and a cascade detection framework. The proposed method consists of three main modules: image preprocessing, license plate detection and license plate confirmation. Considering the diversities of Chinese license plate, we first get the gradient images to unify plate forms through image preprocessing. The license plate will be detected roughly by using the cascade AdaBoost classifier in the next step. Finally, several heuristic judgment strategies and a voting-based method are used to verify the candidate license plates. The effectiveness of our method is validated with an experimental study in license plate detection.     

未系安全带智能识别中安全带定位关键方法研究

安全带定位是实现机动车未系安全带智能识别的关键。针对道路监控图像特点,提出一种基于梯度变换的安全带定位方法。该方法在对卡口图像进行预处理的基础上,采用自适应阈值边缘检测算法以及积分投影方式定位车辆位置,设立车牌检测区域,以减少运算量,降低干扰,同时利用训练得到的Haar分类器识别车牌位置,通过逼近方式切取车辆右侧图像。最后采用梯度变换算法求得车窗各边缘坐标,实现车窗精准定位,并计算得到安全带位置。试验表明,该方法可实现安全带的准确定位,具有较好的实用性,为后续安全带识别奠定基础。     

Detection and tracking strategy for license plate detection in video

In this paper, we present a novel method to detect license plates in video sequences automatically. The framework mainly integrates the cascade detectors method and the Tracking Learning Detection (TLD) algorithm. The cascade detectors are used to detect license plates, and the TLD algorithm is adopted to track the license plate regions. The license plates in the first frame image are detected by the cascade detectors to build the original tracking list, the tracking results and the detection results in following frames will be compared, and the newly appearing license plate information will be added to the tracking list. Meanwhile, the tracking results existing in the current tracking list would be replaced by the corresponding detection results with higher degree of confidence. We demonstrate the effectiveness of our algorithm for license plate detection task on a road intersection dataset, and the experimental evaluation shows the detection performance has been greatly improved by synthetically using the detection and tracking strategy.     

Simple method for simultaneous determination of the phase retardation and fast axis of a wave plate

A simple method for simultaneous determination of the phase retardation and fast axis of a wave plate is presented. In this method, double light path compare system is adopted to achieve better accuracy. In the main optical path, laser beam passes successively through a polarizer, a wave plate to be measured, an analyzer, and then is incident on a detector. In the reference optical path, another detector is used to monitor the fluctuation of the light source. With rotation of the wave plate, the maximum and minimum output light intensity, rotation angle of the wave plate are detected in the main light path; corresponding light intensity are simultaneously detected in the reference light path. Based on the light intensity and the rotation angle, the phase retardation and fast axis of the wave plate can be determined simultaneously. The main advantage of this method is its simplicity of apparatus, easy operation, low cost, and high accuracy. We believe that the method reported in this paper should be a useful approach to measure a wave plate without requiring any complex and expensive components.     

基于BP神经网络的车牌字符识别算法研究

车牌字符识别是车牌识别系统中的关键环节。采用图像处理和神经网络相结合的方法设计新的车牌字符识别算法,先对分割出的车牌字符进行归一化处理,然后进行SOBEI．边缘检测和角点特征提取,最后输入BP神经网络进行训练、识别,其中BP神经网络模型属于改进型神经网络。通过一系列神经网络训练和仿真实验,车牌识别速度和正确率得到了明显的提高。     

基于多核的车牌识别的架构实现

多核技术是现在提高芯片性能的主要方法。区别于传统以PC和DSP为核心的车牌识别系统,以FPGA为核心,利用SOPC技术构建了车牌识别多核处理器。给出了一种基于多核的车牌识别架构,在该多核处理器中,以3个Nios II 软核为主要处理器核处理车牌定位、字符特征识别提取及识别等处理,同时构建硬件加速器作为协处理器处理图像增强、边缘检测和膨胀、腐蚀等数学形态学处理。在CQ片上路由器基础上,构建了NOC用以实现片上多核通信。另外,为了保证路由器与多处理器核之间的快速、并行通信,加入了数据驱动模块。整个系统在Altera Cyclone IV FPGA上实现了车牌的识别。这种片上系统设计方法具有硬件设计灵活,可扩展性强等优点,能有效地降低系统软硬件设计的难度,缩短开发周期,并提高设计的可靠性。     

Dynamic stability of linearly varying thickness viscoelastic rectangular plate with crack and subjected to tangential follower force

Based on the two-dimensional viscoelastic differential constitutive relation and the thin plate theory, the differential equations of linearly varying thickness viscoelastic plate with crack and subjected to uniformly distributed tangential follower force in the Laplace domain are established, and the expression of the additional rotation induced by the crack is given. The complex eigenvalue equations of linearly varying thickness viscoelastic plate constituted by elastic behavior in dilatation and the Kelvin-Voigt laws for distortion with crack and under the action of uniformly distributed tangential follower force are obtained by the differential quadrature method. The generalized eigenvalue under different boundary conditions is calculated, and the curves of real parts and imaginary parts of the first three order dimensionless complex frequencies versus uniformly distributed tangential follower force are obtained. The effects of the aspect ratio, the thickness ratio, the crack parameters and the dimensionless delay time on the dynamic stability of the viscoelastic plates are analyzed.