Computer system providing hands free user input via optical means for navigation or zooming

A system and method are described for selectively providing display data to a display device dependent upon an optically detected proximity of a user's face to a camera. One embodiment of a computer system includes the camera, the display device, and a processing system. The camera produces image signals representing a first image and a second image of the user's face, wherein the first image precedes the second image in time. The processing system receives the image signals and analyzes the first and second images to determine the proximity of the user's face to the camera. More specifically, the processing system compares the first and second images to determine the proximity of the user's face to the camera in the second image relative to the proximity of the user's face in the first image. The processing system provides the display data to the display device dependent upon the proximity of the user's face to the camera. In order to determine the proximity of the user's face to the camera, the processing system may compare: (i) a size of the user's face in the first and second images, and/or (ii) a distance between selected facial features of the user in the first and second images. The processing system may provide more of the display data to the display device when the user's face is closer to the camera, and may provide less of the display data to the display device when the user's face is farther from the camera.