A head posture estimating unit estimates, from a face image of a person photographed by a camera, a head posture of the person in a camera coordinate system. A head coordinate system eyeball central position candidate setting unit sets candidates of an eyeball central position in a head coordinate system based on two-point eyeball feature coordinates expressed in the head coordinate system. A camera coordinate system eyeball central position calculating unit calculates an eyeball central position ({right arrow over (a)}) in the camera coordinate system based on the head posture resulting from the estimating of the head posture estimating unit, the candidates of the eyeball central position set by the head coordinate system eyeball central position candidate setting unit, and a pupil central position detected from the face image. An eyeball parameter estimating unit estimates an eyeball central position (O) and an eyeball radius (r) in the head coordinate system based on the eyeball central position ({right arrow over (a)}) in the camera coordinate system.
Eyeball parameter estimating device and method