PURPOSE: To improve the accuracy of a video image processing for traffic management so as not to be affected by rain and shadows. CONSTITUTION: This method is provided with steps for generating video images 103 provided with a multi-spectrum video source 102, converting analog color data included in the generated video images 103 to digital color data by a color digitizer 104 for a signal processing thereafter, extracting the digital color data from the specified area of the generated video images by a digital signal processor 106 and utilizing a digital color extracted for identifying a color discriminated from background colors by a central processing unit 108. COPYRIGHT: (C)1993,JPO