1. On a computing device, a method of tracking an eye, the method comprising: receiving image data from an image sensor; detecting a face of the user in the image data; locating the eye in a region of the face in the image data to obtain an eye image; normalizing one or more of a scale and an illumination of the eye image; fitting an ellipse to an iris of the eye in the eye image; and outputting a determination of an eye gaze direction based upon the ellipse fitted.