METHOD AND APPARATUS FOR AUTOMATICALLY ACQUIRING FACIAL, OCULAR, AND IRIS IMAGES FROM MOVING SUBJECTS AT LONG-RANGE

• US 20120154536A1
• Filed: 02/17/2011
• Published: 06/21/2012
• Est. Priority Date: 02/17/2010
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Cowan, Cregg, Burns, John Brian, Stoker, David, Agrawal, Motilal, van der Laan, Jan Edward
• Granted Patent: US 10,178,290 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19
• CPC Class Codes: G06V 40/19 Sensors therefor
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 23/45 for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• CPC Class Codes: H04N 23/61 based on recognised objects
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

The present invention relates to a method and apparatus for long-range facial and ocular acquisition. One embodiment of a system for acquiring an image of a subject'"'"'s facial feature(s) includes a steerable telescope configured to acquire the image of the facial feature(s), a first computational imaging element configured to minimize the effect of defocus in the image of the facial feature(s), and a second computational imaging element configured to minimize the effects of motion blur. In one embodiment, the detecting, the acquiring, the minimizing the effect of the motion, and the minimizing the effect of the defocus are performed automatically without a human input.

Claims

1. A system for acquiring an image of a facial feature of a subject, the system comprising:

a steerable telescope configured to acquire the image of the facial feature;

a first computational imaging element configured to minimize an effect of defocus in the image of the facial feature; and

a second computational imaging element configured to minimize an effect of motion blur in the image of the facial feature.

2. The system of claim 1, wherein the steerable telescope comprises:

a low-resolution sensor having a first field of view; and

a high-resolution sensor having a second field of view.

3. The system of claim 1, further comprising:

a subject tracker for detecting the subject and guiding the steerable telescope to focus on the subject.

4. The system of claim 3, wherein the subject tracker is a three-dimensional stereo-based camera.

5. The system of claim 3, further comprising a range finder for refining image motion and range motion measurements made by the subject tracker.

6. The system of claim 1, further comprising:

a diffuse, trigger-pulsed, speckle-free light source; and

a beam expanding telescope comprising a Fresnel lens.

7. The system of claim 6, wherein the light source is a pulsable array of Vertical Cavity Surface Emitting Lasers (VCSELs).

8. The system of claim 1, further comprising:

a three-dimensional trajectory generator that includes logic controls that determine where to aim the steerable telescope; and

an executable program that generates trajectory predictions of a plurality of facial features of the subject, the plurality of facial features including an ocular region and pupils, within a field of view of the steerable telescope.

9. The system of claim 1, further comprising:

a gaze monitor for identifying a location of the facial feature and tracking a gaze direction of the subject.

10. The system of claim 9, wherein a gaze angle is determined by measuring a location of a specular glint relative to a circumference of a pupil of the subject, and the pupil is identified through a brightness of a retinal reflection and an existence of a symmetric pair with respect to a symmetry axis of a face of the subject.

11. The system of claim 1, wherein the first computational imaging element is an optical element.

12. The system of claim 11, wherein the optical element is a lattice focal lens, a micro-lens array, or a movable element that generates a focal sweep trajectory.

13. The system of claim 1, wherein the second computational imaging element is a coded exposure or a motion invariant photography element.

14. A method for acquiring an image of a facial feature of a subject, the method comprising:

detecting the subject looking at an image capturing device;

acquiring the image of the facial feature in response to the detecting;

minimizing an effect of a motion in the image of the facial feature; and

minimizing an effect of a defocus in the image of the facial feature.

15. The method of claim 14, wherein the detecting comprises:

determining that the subject meets a set of detection criteria; and

tracking a motion of a gaze of the subject until the subject looks at the image capturing device.

16. The method of claim 14, wherein the acquiring comprises:

switching a state of a light source from a low-energy/high pulse repetition rate state to a higher-energy/single pulse state in response to the detecting; and

triggering an emission of a short pulse of light onto a forward gazing head of the subject simultaneously with a high resolution sensor exposure.

17. The method of claim 14, wherein the minimizing the effect of the motion is based on a dynamic tracking of one or more feature trajectories that minimizes motion of the feature within the field of view of the high resolution sensor plane.

18. The method of claim 14, wherein the minimizing the effect of the defocus is based on a use of a computational imaging element that allows defocus to be reduced after acquisition of a high resolution image.

19. The method of claim 18, wherein a reduction of the defocus is achieved by exposing a high resolution sensor while an apparent focus of a scene is rapidly translated through a sensor plane.

20. The method of claim 18, wherein a reduction of the defocus is achieved by an array of lenses placed in a location of a pupil location of an imaging system executing the method after a telescope eyepiece.

21. The method of claim 18, wherein a reduction of the defocus is achieved by a microlens array placed near a high resolution sensor plane.

22. The method of claim 14, wherein the minimizing the effect of the motion is based on the use of a computational imaging element that allows a motion blur to be reduced after an acquisition of a high resolution image.

23. The method of claim 22, wherein a reduction of the motion blur is achieved by exposing a high resolution sensor while a coded emission from a collimated light source is projected at range onto a head of the subject.

24. The method of claim 22, wherein a reduction of the motion blur is achieved by accelerating a steering mirror contained within a steerable telescope through a range of velocities, wherein one velocity in the range of velocities which minimizes an apparent motion of the facial feature within a field of view of a high resolution sensor.

25. The method of claim 14, further comprising:

adjusting a focus of the image of the facial feature.

26. The method of claim 14, wherein the detecting, the acquiring, the minimizing the effect of the motion, and the minimizing the effect of the defocus are performed automatically without a human input.

27. A computer readable storage device containing an executable program for acquiring an image of a facial feature of a subject, where the program performs steps comprising:

detecting the subject looking at an image capturing device;

acquiring the image of the facial feature in response to the detecting;

minimizing an effect of a motion in the image of the facial feature; and

minimizing an effect of a defocus in the image of the facial feature.

28. A system for acquiring an image of a facial feature of a subject, the system comprising:

a steerable telescope configured to acquire the image of the facial feature;

a high-repetition strobe synchronized with the steerable telescope for creating a glint in an ocular region of the subject; and

a gaze monitor for identifying when a position of the glint relative to a center of a pupil of the subject indicates that the subject is looking at the steerable telescope.

29. A method for acquiring an image of a facial feature of a subject, the method comprising:

illuminating an ocular region of the subject using a high-repetition strobe in order to create a glint in the ocular region;

determining that the subject is looking at an image capturing device, based on a position of the glint relative to a pupil of the subject; and

acquiring the image of the facial feature in response to the determining.