Patent ID: 8878773

Claim:
A computer-implemented method of enabling a user to provide input to an electronic device, comprising: under control of one or more computing systems configured with executable instructions, capturing at least one ambient light image including at least a portion of a user of the electronic device; determining an approximate head position of the user with respect to the electronic device based at least in part upon the at least one ambient light image; capturing a first image including infrared (IR) light using a first infrared sensor, the IR light being emitted by an infrared source of the electronic device and being reflected by at least one retina of the user, wherein the first infrared sensor is positioned substantially adjacent to the infrared source; capturing, concurrently with the first image, a second image using a second infrared sensor positioned a distance away from the infrared source on the electronic device, the second image not including any of the IR light emitted by the infrared source and reflected from the at least one retina; selecting a first portion of the first image and a second portion of the second image, each of the first portion and the second portion corresponding to the approximate head position detected in the at least one ambient light image; comparing corresponding intensity values between the first portion and the second portion to determine a relative position of the at least one retina of the user; determining a relative orientation of the user with respect to the electronic device based at least in part upon the determined relative position of the at least one retina; and based at least in part upon the relative orientation, providing a corresponding input to the electronic device.