Unconstrained Pupil Detection TechniqueUsing Two Light Sources And The ImageDifference Method

For developing a human-computer interface applying eye-gaze, we have already proposed a noncontact, unconstrained video-based pupil detection technique using two light sources and the image difference method. The detected pupil position in the difference image is utilized together with the glint (corneal reflection light of an infrared light source) position for eyegaze position determination. In this paper, the hardware for real-time image differentiation was developed. This image differenciator made realtime pupil possible, by applying the pupil detector including the noise reducer, which had been already developed. For stably detecting the glint and the pupil, it was clarified that the pupil brightness is influenced by the pupil area and the power of infrared light irradiated for the eye. For stabilizing the pupil brightness in the difference images, a method which utilized this characteristics was proposed. This method made pupil and glint center detection stabler.