1. Method of operating a vision system of the type employing a camera means for providing an image of at least a portion of an object viewed by the camera means, the image comprising a plurality of adjacent pixels, comprising the steps of: (a) viewing at least a portion of the object with the camera means and generating a target signature form the image; (b) comparing at least a portion of the target signature to a plurality of sub pixel signatures, each sub pixel signature corresponding to a unique sub pixel position between pixel positions; (c) determining which sub pixel signature most closely matches the target signature based upon the result of the comparison; and (d) providing an indication of position of the object based upon the sub pixel signature determined to most closely match the target signature.