Method and apparatus for associating pupils with subjects

Abstract

A method and apparatus analyzes a scene to determine which pupils correspond to which subjects. First, a machine-readable representation of the scene, such as a camera image, is generated. Although more detail may be provided, this representation minimally depicts certain visually perceivable characteristics of multiple pupil candidates corresponding to multiple subjects in the scene. A machine such as a computer then examines various features of the pupil candidates. The features under analysis include (1) visually perceivable characteristics of the pupil candidates at one given time (“spatial cues”), and (2) changes in visually perceivable characteristics of the pupil candidates over a sampling period (“temporal cues”). The spatial and temporal cues may be used to identify associated pupil pairs. Some exemplary spatial cues include interocular distance, shape, height, and color of potentially paired pupils. In addition to features of the pupils themselves, spatial cues may also include nearby facial features such as presence of a nose/mouth/eyebrows in predetermined relationship to potentially paired pupils, a similarly colored iris surrounding each of two pupils, skin of similar color nearby, etc. Some exemplary temporal cues include motion or blinking of paired pupils together, etc. With the foregoing examination, each pupil candidate can be associated with a subject in the scene.