1国外汽车牌照自身特征的复杂性  

1) 字符、字母、数字混合。车牌不单单有英文字母和阿拉伯数字，还有字符。

2) 颜色种类多。国外的车牌颜色种类多样，复杂，有些还有图片背景

4) 车牌格式多。车牌格式很多，包括：民用车牌、公安**车牌、武警车牌、军车车牌、外交车牌、特种车牌、消防车牌等。  

5) 悬挂方式多样化。汽车车牌的悬挂方式不**，由于不同汽车公司出产的汽车型号和外形各有不同，导致了车牌的悬挂位置不**。比如出租，政府单位，领事馆单位，车牌格式在国外也多种多样。外部环境影响  

1) 外部光照条件各不相同，白天和晚上的光照各不相同。光照对采集的图像质量产生很大的影响。不同的光照角度对车牌光照的不均匀影响也很大。不同的气候条件、背景光照环境、车牌反光程度都决定了车牌的亮度特征。在特征提取时，光照过亮或者过暗都会影响车牌识别的准确率。

2) 外界背景的复杂程度也影响车牌的定位准确率。背景中和车牌区域当中 有许多和车牌特征相似的长方形区域，这些容易给车牌定位造成误判导致车牌定位的准确率降低。

3拍摄角度问题  

实际工程当中的拍摄角度相对于车辆的行驶方向一般是正上方、左侧和右侧。如果拍摄的角度越小，车牌在平面图像中的变形越小，识别效果越好。 根据智能交通系统的结构可知，摄像机采集到的图像均为系列图像，而由于外部环境的影响，车牌识别系统采用的图像不一定是**的.

YUXINTECH车牌识别一体机

为了能尽可能提高识别率和实现国外车牌识别，我公司自主研发了YUXINTECH车牌识别一体机。它以计算机视觉处理、数字图像处理、模式识别等技术为基础，对摄像机所拍摄的车辆图像或者视频图像进行处理分析，得到每辆车的车牌号码，从而完成识别过程。**主要的是它集成了一百多个国家的车牌算法，可以轻松识别各个国家的车牌。

高清车牌识别摄像机是内部带有DSP处理器的高清晰度摄像机。该摄像机带有内置视频移动侦测及车牌号码识别功能。用户可使用网络接口检索OCR结果和图像。该系列摄像机专为停车场，公路、收费站、红绿灯检测应用而设计，功能强大、重量轻和功耗低。

车牌识别一体机旨在完成车牌的识别，拥有完善的开发包和软件接口方便与其它的系统进行整合。产品包括车辆经过时触发，摄相机抓拍，车牌识别，数据储存和接口的数据传输几大部分。客户端在收到识别结果之后，可以做出比对，收费计算，放行等相应的作业流程或后台处理。

Foreign license plate recognition machine Asia Europe America Africa Australia India Russia license plate recognition integrated machine license plate recognition parking management system

1 The complexity of the characteristics of foreign auto license plates

1) Mixed characters, letters, and numbers. License plates don't just have English letters and Arabic numerals, but also characters.

2) There are many types of colors. Foreign license plate colors are diverse and complex, and some have picture backgrounds.

4) There are many license plate formats. There are many license plate formats, including: civil license plates, public security police license plates, armed police license plates, military license plates, diplomatic license plates, special license plates, fire license plates, etc.

5) Diversified suspension methods. The suspension method of the automobile license plate is not unique. Because the models and shapes of the cars produced by different automobile companies are different, the suspension position of the license plate is not unique. For example, rental, government units, consular units, license plate formats are also diverse in foreign countries. External environmental impact

1) External lighting conditions vary, and day and night illumination varies. Illumination has a large impact on the quality of the acquired image. Different illumination angles have a great influence on the uneven illumination of the license plate. Different climatic conditions, background lighting environment, and license plate reflection degree all determine the brightness characteristics of the license plate. When the feature is extracted, the illumination is too bright or too dark, which will affect the accuracy of license plate recognition.

2) The complexity of the external background also affects the positioning accuracy of the license plate. In the background and in the license plate area, there are many rectangular areas similar to the license plate characteristics, which are easy to cause misjudgment of the license plate positioning and lead to a lower accuracy of the license plate positioning.