1. A method of detecting a feature of a vehicle in an image of said vehicle, said method comprising the steps of: providing a digitized image of said vehicle, said image comprising a plurality of intensities corresponding to a domain of points on an 2-dimensional grid; providing a first filter mask over a first subdomain of said image, wherein said filter mask is placed to detect a feature in said image; calculating a function of a gradient of said image inside said first masked subdomain; and detecting the presence or absence of a vehicle feature within said first masked subdomain based on the value of said gradient function.