A method and apparatus for characterizing pixels in an image of an object surface by providing at least two images of the surface wherein each pixel has a unique location common to all of the images; comparing each pixel value at each location to an identification matrix; and identifying the region in which each pixel is located based on the comparison. The Viterbi decode algorithm is at least one of a Bit Serial decode algorithm, and block based decode algorithm. The base may include a mount and a stem inserted into the interior bore of the dart body at the first end of the dart. Outside-air intaken by an air intake fan flows through the upper and lower ducts separately. The second support members are connected to the lift screws to be vertically movable therewith, respectively.