1. A method for interpreting a control gesture to a mobile device having an image sensor capable of providing a sequence of images, comprising: comparing a second image of the sequence of images to a first image of the sequence of images, the comparing including a comparison between content of the second image and the first image; if the second image is substantially identical to the first image and has the same content, setting the second image as a background image; detecting an object if a third image of the sequence of images differs substantially from the background image; storing only the pixels of said object in the third image that differ substantially from the background image; using the stored pixels of the object, determining if the detected object is stationary based at least in part on an absence of change of the object among multiple images of the sequence of images; if the detected object has been determined to be stationary, storing only the pixels of the detected stationary object and determining initial object characteristics from the stored pixels; detecting a change in the detected object among multiple images of the sequence of images; using the initial object characteristics, determining one or more parameters associated with the detected change; interpreting a user command indicated by the determined one or more parameters, wherein the interpreted user command is ignored if the interpreted user command is received within a specified time after a previous user command; and executing an action associated with the interpreted user command.