1. A method of detecting a vehicle represented in an image of a night time scene, the method comprising the steps of: (a) identifying a candidate pair of headlights in an image based on luminance of points in the image; (b) identifying a sub-image of the image sized to include a candidate vehicle having the pair of candidate headlights; and (c) determining whether the candidate vehicle is a vehicle represented in the image by testing the sub-image for the presence of predetermined features of a vehicle other than the headlights.