1. A computer-implemented method of identifying an authorized user of a computing device, comprising: capturing image information using at least one image capture element of the computing device; analyzing, by the computing device, the image information to identify a position of at least one feature of a person near the computing device; tracking the at least one feature over a period of time in the image information; determining, by the computing device, a set of points including both position and time information for the at least one feature during at least a portion of the period of time; comparing the set of points to at least one gesture pattern stored for the authorized user of the computing device, the at least one gesture pattern including: (a) a path of movement for a gesture, (b) at least one of relative timing, acceleration, or velocity information for a plurality of points along the path of movement, and (c) one or more user-specific measurements relating to a manner of the authorized user performing the gesture; and providing an indication that the person is the authorized user of the computing device when the set of points matches the at least one gesture pattern stored for the authorized user with at least a minimum level of certainty.