US 6,959,102 B2 · Method for increasing the signal-to-noise in IR-based eye gaze trackers

Abstract

The accuracy of eye gaze trackers is used in the presence of ambient light, such as sunlight, is improved. The intensity of sunlight and its constituent wavelengths of light, such as infrared radiation, do not vary rapidly. During the inter-frame interval of video cameras (typically 1/30th of a second), the level of ambient infrared radiation can be considered nearly constant. In a first embodiment, the modulation of the IR illuminator is synchronized with each frame of the camera such that the illuminator alternates between on and off with each subsequent frame. If one considers a sequence of such frames, then the image captured in the first frame contains both the illuminator signal and the ambient radiation information. The image captured in the second frame contains only the ambient radiation information. By subtracting the second frame from the first frame, a new image is formed that contains only the information from the illuminator signal. The resulting image can then be used by the conventional eye tracker system to compute the direction of eye gaze even in the presence of an ambient IR source.

Claims21

Dependent claims

A system for improving signal-to-noise ratio for an eye gaze tracker, comprising:

an illuminator for illuminating a user's eye with light radiation;
a camera for detecting an illuminator signal from said illuminator light radiation reflected from the user's eye and also detecting ambient light noise, said camera outputting an output signal;
means for synchronizing said illuminator to turn on with a first interval of said camera and turn off with a second interval of said camera;
means for digitizing said output signal and capturing a first image from said first interval having an illuminator signal portion and an ambient light noise portion and capturing a second image from said second interval having said ambient light noise portion;
and
means for subtracting said second image from said first image to produce an output image comprised of said illuminator signal portion, said output image being devoid of said ambient light noise portion.

3 more elements

Dependencies are inferred from the claim text.

Method for increasing the signal-to-noise in IR-based eye gaze trackers

Life of this patent

Method for increasing the signal-to-noise in IR-based eye gaze trackers

Life of this patent

Abstract

Claims21