1. A method for tracking a follicular unit, the method comprising: identifying a follicular unit in a first image of a body surface containing follicular units; computing a signature of the follicular unit in the first image, wherein the signature is unique to the follicular unit and comprises a plurality of characteristics of the follicular unit; computing a motion vector associated with movement of the body surface by comparing the first image and a second image of the same body surface, the second image being taken at a different point in time relative to the first image; and defining a search region according to and in a direction of the motion vector, wherein the search region comprises an area within a predetermined distance from the motion vector; and searching for the signature of the follicular unit in the search region to label the follicular unit in the second image.