This paper presents a real time image processing system, with a stereo color image instrument being chained to Matlab platform, for automatically identifying automobiles ahead and then calculating the distance between the instrument and the object. A fuzzy rule based on a color model (hue-saturation-value) is proposed to extract the color characteristic of the taillights, motivated by the fact that all the automobiles have a pair of red color taillights and the HSV model conforms to the color consistency of human vision system. In order to accommodate varying background colors and illumination conditions, the rear window or the shadow of a automobile is further identified by using the value information in the HSV model. Moreover, a new algorithm is presented here for quick filtering out the noise consisted of the granulated or slim pixels. Finally, experimental results are reported and analyzed.