1. A method for invoking an operation of a communication terminal in response to registering and interpreting a predetermined motion or pattern of an object, the method comprising: receiving an indication of a predetermined motion or pattern of a single occurrence of a hand input gesture received from a digital camera of the communication terminal; identifying at least a first and second centroid in the object; identifying at least one convex hull in the object; matching the hand input gesture received from the digital camera with a reference gesture object selected from a set of reference gesture objects based on a positional relationship of the at least first and second centroids in the object and a change in size of the convex hull; and executing a command related to an item of a display of the communication terminal in response to and upon matching the single occurrence of the hand input gesture received from the digital camera with the reference gesture object.