Object distance determination from image

Patent metadata

Field	Value
Publication number	US-10595014-B2
Application number	US-201214342899-A
Country	US
Kind code	B2
Filing date	Sep 21, 2012
Priority date	Sep 28, 2011
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A system for determining a distance to an object comprises an image capture device (101) which has a coded aperture and an image sensor which is positioned out of a focus plane of the coded aperture. A receiver (103) receives an image of a scene from the image sensor and a detector (105) detects at least two image objects of the image corresponding to ghost images of the object resulting from different openings of the coded aperture in response to an optical characteristic of the object. A distance estimator (107) then determines a distance to the object in response to a displacement in the image of the at least two image objects. The distance may be to a person and the image may be a bright pupil image wherein pupils are enhanced by reflection of light by the retina. The image may be compensated by a dark pupil image of the scene.

First claim

The invention claimed is:

1. An apparatus, comprising:
an image capture device, wherein the image capture device having a coded aperture and an image sensor,
wherein the image sensor is disposed out of a focal plane for a scene object which is present together with a background in a scene which is imaged by the image capture device,
wherein the coded aperture is formed by two disjoint openings,
wherein each opening has a zone plate pattern,
wherein the two disjoint openings produce two corresponding image objects at the image sensor, and
wherein the two image objects correspond to ghost images of the scene object;

a receiver, wherein the receiver is configured to receive an image of the scene from the image sensor of the image capture device;
a detector, wherein the detector is configured to:
search the image of the scene to identify image areas which have at least one image characteristic corresponding to one or more optical characteristics of the scene object, wherein the one or more optical characteristics include a radiation characteristic of the scene object towards the image capture device, and
detect, in the identified image areas of the image, the two image objects, based on a presence in the identified image areas of the at least one image characteristic corresponding to one or more optical characteristics of the scene object;

a distance estimator, wherein the distance estimator is configured to determine a distance to the scene object in response to a displacement in the image of the two image objects, and
a light source for illuminating the scene, the light source having a characteristic arranged to emphasize the one or more optical characteristics of the scene object such that a difference between the one or more optical characteristics of the scene object and background optical characteristics of the background is increased,
wherein the apparatus is arranged to determine the displacement in the image of the two image objects in response to an interference pattern produced by the zone plate patterns of the two openings.

2. The apparatus of claim 1 , wherein the image is a bright pupil image of an eye, and the one or more optical characteristics includes a characteristic of light retroreflected by a retina of the eye towards the image capture device.

3. The apparatus of claim 2 , wherein the image is a first image and wherein the receiver is arranged to receive a second image of the scene from the image sensor, the second image being a dark pupil image; and wherein the detector is arranged to compensate the first image for the second image prior to detecting the two image objects.

4. The apparatus of claim 3 , wherein the light source is positioned substantially on an optical axis of the image capture device; and the apparatus includes a light source controller arranged to switch on the light source for the first image and to switch off the light source for the second image.

5. The apparatus of claim 2 , wherein the two image objects correspond to a first pupil of a person, wherein the detector is arranged to detect an additional two image objects in the image corresponding to ghost images of a second pupil of the person produced by the openings of the coded aperture, and wherein the distance estimator is arranged to determine the distance in response to a displacement in the image of the additional two image objects.

6. The apparatus of claim 2 ,
wherein the two image objects correspond to a first pupil of a person,
wherein the detector is arranged to detect an additional two image objects in the image corresponding to ghost images of a second pupil of the person produced by the openings of the coded aperture, and
wherein the distance estimator is arranged to determine an orientation of a head of the person in response to a difference between the displacement in the image of the two image objects and a displacement in the image of the additional two image objects.

7. The apparatus of claim 1 , wherein the two image objects are disjoint image objects.

8. A system comprising:
an image capture device having a coded aperture and an image sensor, wherein the image sensor is disposed out of a focus plane for a scene object which is present together with a background in a scene which is imaged by the image capture device, wherein the coded aperture is formed by two openings, and
wherein the two openings produce two corresponding image objects at the image sensor, wherein the two image objects correspond to ghost images of the scene object;
a receiver, wherein the receiver is configured to receive an image of a scene from the image sensor;
a detector, wherein the detector is configured to:
identify image areas of the image which have at least one image characteristic corresponding to one or more optical characteristics of the scene object, wherein the one or more optical characteristics include at least one of a color, a brightness, and a pattern of the scene object; and
detect, in the identified image areas of the image, the two image objects based on a presence in the identified image areas of the at least one image characteristic corresponding to the one or more optical characteristics of the scene object;

a distance estimator, wherein the distance estimator is configured to determine a distance to the scene object in response to a displacement in the image of the two image objects; and
a light source, wherein the light source is configured to illuminate the scene, wherein the light source has a characteristic arranged to emphasize the one or more optical characteristics of the scene object.

9. The system of claim 8 , further comprising an optical element for attaching to the scene object, the detector being arranged to detect the two image objects in response to an optical property of the optical element.

10. A method comprising:
Illuminating, by a light source, a scene having a scene object together with a background, wherein the light source has a characteristic arranged to emphasize an optical characteristic of the scene object in comparison to a background characteristic of the background;
capturing an image of the scene with an image capture device having a coded aperture and an image sensor,
wherein the image sensor is disposed out of a focal plane for a scene object, wherein the coded aperture is formed by two openings,
wherein the two openings produce in the captured image two corresponding image objects in the captured image, and
wherein the two image objects correspond to ghost images of the scene object;

receiving at a receiver the captured image of the scene from the image sensor of the image capture device;
identifying image areas of the captured image which have an image characteristic corresponding to the optical characteristic of the scene object, wherein the optical characteristic is one of a color, a brightness, and a pattern of the scene object;
detecting by a detector the two image objects in the identified image areas of the captured image based on a presence in the identified image areas of the image characteristic corresponding to the optical characteristic of the scene object; and
determining by a distance estimator a distance to the scene object in response to a displacement in the captured image of the two image objects.

11. An autostereoscopic display system, comprising an apparatus of claim 1 .

12. A computer-readable storage-medium that is not a transitory propagating signal or wave, the medium containing control information for controlling a method for operating an apparatus to determine a distance to a scene object in at least one image of a scene, the method comprising:
illuminating by a light sour

Assignees

• Koninklijke Philips Nv

Inventors

• Muijs Remco Theodorus Johannes
• De Bruijn Frederik Jan
• Gritti Tommaso

Classifications

• G06T2207/10141

  Special mode during image acquisition · CPC title

• G06T2207/30041

  Eye; Retina; Ophthalmic · CPC title

• H04N13/373 Primary

  for tracking forward-backward translational head movements, i.e. longitudinal movements · CPC title

• G06T2200/21

  involving computational photography · CPC title

• G06T7/70

  Determining position or orientation of objects or cameras (camera calibration G06T7/80) · CPC title