Abstract： Modern management methods are needed to administer traffic on account of the economical development and the speedup of urbanization and motorization, which begets the research on Intelligent Transportation System--ITS. With advanced teletronical technology, information technology, artificial intelligence, geographic information system, computer processing, communication, sensor technology and system project technology, ITS establishs transportation system on all orientation, real-time acoup sur and efficaciously, which develop disorder traffic, reduce traffic jam,impove transportation efficacious and safety. Real-time traffic flow plays an very important role in ITS.Currently, magnetic loop detectors are often used to count vehicles passing over them.vision-based video monitoring systems offer larger set of traffic parameters such as vehicle flow, lane changes, etc., can be measured.cameras are much less disruptive to install than loop detectors..Associative digital image processing technology,vision-based video monitioring systems are attached importance and applied. In this paper, an digital image technology used for ITS is discussed in details,including vehicle measeurement, vehicle flow statistic subsystem, lamp control subsystem and taking image subsystem violating the regulations. Thereinto, vehicle measurement is core and base of ITS. The hardware buildup and software buildup are also presented.In addition，we disscuss the future betterment.
