FACE IMAGING SYSTEM AND METHOD FOR CONTROLLING THE FACE IMAGING SYSTEM

• US 20120188355A1
• Filed: 01/24/2012
• Published: 07/26/2012
• Est. Priority Date: 01/25/2011
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Omi, Takuhiro, Watanabe, Taito
• Granted Patent: US 8,767,062 B2
• Time in Patent Office: Days
• US Class Current: 348/78
• CPC Class Codes: A61B 2503/22 Motor vehicles operators, e.g. drivers, pilots, captains
• CPC Class Codes: A61B 2562/0257 Proximity sensors
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/1114 Tracking parts of the body
• CPC Class Codes: A61B 5/1128 using image analysis A61B5/1127 takes precedence
• CPC Class Codes: A61B 5/163 by tracking eye movement, gaze, or pupil change
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6893 Cars
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 20/59 inside of a vehicle, e.g. relating to seat occupancy, driver state or inner lighting conditions
• CPC Class Codes: G06V 20/597 Recognising the driver's state or behaviour, e.g. attention or drowsiness
• CPC Class Codes: G06V 40/16 Human faces, e.g. facial parts, sketches or expressions

Abstract

A projection unit projects light to a predetermined projection region in which a user'"'"'s face is supposed to be located. An imaging unit images a region including the projection region projected with light from the projection unit. A proximity detection unit detects that the user'"'"'s face approaches the projection unit. A first projection control unit causes the projection unit to stop or dim projection of light when the proximity detection unit detects the approach of the user'"'"'s face.

Claims

1. A face imaging system comprising:

a projection unit configured to project light to a predetermined projection region in which user'"'"'s face is supposed to be located;

an imaging unit configured to image a region including the projection region projected with light from the projection unit;

a proximity detection unit configured to detect approach of the user'"'"'s face relative to the projection unit; and

a first projection control unit configured to cause the projection unit to stop or dim projection of light when the proximity detection unit detects approach of the user'"'"'s face.

2. The face imaging system according to claim 1, wherein the proximity detection unit is further configured to detect approach of the user'"'"'s face according to an image captured with the imaging unit.

3. The face imaging system according to claim 2, wherein

the imaging unit has a lens structure configured to cause blur in a region corresponding to an object in the image when the object approaches the projection unit, and

the proximity detection unit includes:

an edge extraction unit configured to extract edge information from the image, the edge information reflecting a feature of an edge in the image, and

an edge determination unit configured to determine whether the edge information extracted with the edge extraction unit has blur.

4. The face imaging system according to claim 3, wherein

the imaging unit is further configured to image the projection region to include a surrounding structure being constant in position relative to the imaging unit, and

the edge determination unit is further configured to compare edge information, which is on a background region corresponding to the surrounding structure in the image, with edge information, which is on an unfixed region other than the background region, thereby to determine whether the edge information on the unfixed region has blur.

5. The face imaging system according to claim 3, wherein the edge determination unit is further configured to compare present edge information with previous edge information, which is on a previous image without blur, thereby to determine whether the present edge information has blur.

6. The face imaging system according to claim 2, further comprising:

a face recognition unit configured to detect a face region corresponding to the user'"'"'s face in the image, wherein

the proximity detection unit is further configured to detect approach of the user'"'"'s face according to a size of the face region when the face recognition unit detects the face region.

7. The face imaging system according to claim 2, further comprising:

an imaging control unit configured to control an exposure condition of the imaging unit;

a second projection control unit configured to control a projection timing of light from the projection unit according to an exposure timing of the imaging unit; and

a concealment detection unit configured to detect concealment of the imaging unit with an obstacle according to the image, wherein

when the concealment detection unit detects concealment of the imaging unit;

the imaging control unit increases an exposure interval of the imaging unit; and

/or

the first projection control unit causes the projection unit to stop projection of light or to dim projection of light.

8. The face imaging system according to claim 1, wherein

the proximity detection unit includes a distance detection unit configured to detect a distance of an object in the projection region, and

the proximity detection unit is further configured to detect approach of an object relative to the projection unit according to the distance detected with the distance detection unit.

9. The face imaging system according to claim 1, further comprising:

a blooming region detection unit configured to detect that;

blooming region occurs entirely in pixels around a center of the image;

or

pixel values of pixels entirely around a center of the image become greater than or equal to a first threshold representing blooming region, wherein

the proximity detection unit is further configured to determine that the user'"'"'s face approaches the projection unit when the blooming region detection unit detects blooming region or detects that the pixel values become greater than or equal to the first threshold.

10. The face imaging system according to claim 1, further comprising:

a black crushing detection unit configured to detect that;

black crushing occurs entirely in pixels around a center of the image;

or

pixel values of pixels entirely around a center of the image become less than or equal to a second threshold representing black crushing, wherein

the proximity detection unit is further configured to determine that the user'"'"'s face approaches the projection unit when the black crushing detection unit detects black crushing or detects that the pixel values become less than or equal to the second threshold.

11. The face imaging system according to claim 1, wherein the face is an eye.

12. The face imaging system according to claim 1, wherein the imaging unit has a lens configuration configured to cause blur in a region in which a depth of field is less than or equal to 20 cm.

13. The face imaging system according to claim 1, wherein the imaging unit has a lens configuration configured to decrease modulation transfer function (MTF) in a specific region.

14. The face imaging system according to claim 13, wherein the proximity detection unit is further configured to:

sample temperature information on temperature of a lens of the imaging unit; and

change a detection condition of approach of the user'"'"'s face according to the sampled temperature information.

15. A method for controlling a face imaging system including a projection unit and an imaging unit, the method comprising:

causing the projection unit to project light to a projection region in which a user'"'"'s face is supposed to be located;

causing the imaging unit to image the projection region, the imaging unit configured to cause blur in a region corresponding to an object approaching the projection unit;

determining whether the imaged projection region has blur caused by the imaging unit;

detecting approach of the user'"'"'s face relative to the projection unit on determination that the imaged projection region has blur; and

causing the projection unit to stop or dim projection of light on detection of approach of the user'"'"'s face.

16. A non-transitory computer readable medium comprising instructions executed by a computer, the instructions including the method according to claim 15.