Measurement of Eyeball Rotational Movements in the Dark Environment

It is difficult to measure rotational eye movement constantly from "almost black eyeball image" acquired under the condition that the brightness of an image content being watched by a user is very low or the condition that almost no light is irradiated from its surrounding environment. To solve this problem, the authors developed a new method for measuring rotational eye movement at high accuracy by enhancing the contrast in the image of the vessels on the white of the eyeball, with small blue LED light irradiation as auxiliary light. In our evaluation experiment, the images of rotational eye movements were captured, and data on the vessel positions were obtained by both visual measurement and this system to evaluate the estimated error and processing speed. The result suggests that our proposed system is capable of measuring rotational eye movement with an average of estimated errors equal to or lower than 0.24 degrees, even with almost black eyeball image.