Subject tracking apparatus, camera having the subject tracking apparatus, and method for tracking subject

• US 9,063,290 B2
• Filed: 07/12/2012
• Issued: 06/23/2015
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Takeuchi, Hiroshi, Muramatsu, Keiko
• Primary Examiner(s): Tran, Philip B
• Application Number:
  US13/547,053
• Publication Number:
  US 20120274785A1
• Time in Patent Office: 1,076 Days
• Field of Search: 348/169, 348/345, 382/103
• US Class Current: 1/1
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: G02B 7/28 Systems for automatic generation of focusing signals
• CPC Class Codes: G03B 13/36 Autofocus systems
• CPC Class Codes: H04N 23/61 based on recognised objects
• CPC Class Codes: H04N 23/635 Region indicators; Field of view indicators
• CPC Class Codes: H04N 23/671 in combination with active ranging signals, e.g. using light or sound signals emitted toward objects
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/73 by influencing the exposure time

Abstract

A subject tracking apparatus includes a light detector, a focus detector, and a tracking controller. The focus detector is configured to detect focus information at a plurality of focus detection regions in a view of an image. The focus information includes at least focus information detected at a subject region of a subject in the view. The tracking controller is configured to determine at least one first region having substantially same light information as light information detected at the subject region from among a plurality of light measurement regions, to determine at least one second region having substantially same focus information as the focus information detected at the subject region from among the plurality of focus detection regions, and to determine reference information for tracking the subject in the view based on the at least one first region and the at least one second region.

Claims

1. A subject tracking apparatus comprising:

a light detector configured to detect light information based on light from a subject to be tracked at a plurality of light measurement regions in a view of an image, the light information including at least light information detected at a subject region of the subject in the view;

a focus detector configured to detect focus information at a plurality of focus detection regions in the view, the focus information including at least focus information detected at the subject region of the subject in the view; and

a tracking controller configured to;

determine at least one first region having same light information as the light information detected at the subject region from among the plurality of light measurement regions,

determine at least one second region having same focus information as the focus information detected at the subject region from among the plurality of focus detection regions, and

determine reference information for tracking the subject in the view based on the at least one first region and the at least one second region.

2. The subject tracking apparatus according to claim 1,

wherein the reference information includes information of a third region that includes the subject region, and

wherein the tracking controller is configured to determine the third region where the at least one first region and the at least one second region overlap.

3. The subject tracking apparatus according to claim 1, wherein

the tracking controller configured to:

determine whether the subject moves closer to or moves away from the subject tracking apparatus based on the focus information of the subject, and

change the reference information depending on the determination of whether the subject moves closer to or moves away from the subject tracking apparatus.

4. The subject tracking apparatus according to claim 3,

wherein the reference information includes information of a third region that includes the subject region, and

wherein the tracking controller configured to:

determine the third region where the at least one first region and the at least one second region overlap, and

change the reference region in size depending on the determination of whether the subject moves closer to or moves away from the subject tracking apparatus.

5. The subject tracking apparatus according to claim 1,

wherein the reference information includes at least one of color information and luminance information, and

wherein the tracking controller is configured to track the subject based on at least one of the color information and the luminance information.

6. The subject tracking apparatus according to claim 1,

wherein the reference information includes a hue value, and

wherein the tracking controller is configured to:

select candidates of the subject based on the hue value, and

select the subject from among the candidates of the subject based on the focus information detected at the plurality of focus detection regions.

7. The subject tracking apparatus according to claim 1,

wherein the focus information includes a defocus amount,

wherein the light information includes at least one of color information and luminance information, and

wherein the tracking controller is configured to track the subject based on the defocus information and at least one of the color information and the luminance information.

8. The subject tracking apparatus according to claim 1,

wherein the light detector comprises an image sensor with a color filter, and

wherein the view of the image corresponds to a view of an image acquired by the image sensor.

9. A camera for picking up an image through an optical system, comprising:

a subject tracking apparatus comprising;

a light detector configured to detect light information based on light from a subject to be tracked at a plurality of light measurement regions in a view of an image, the light information including at least light information detected at a subject region of the subject in the view;

a focus detector configured to detect focus information at a plurality of focus detection regions in the view, the focus information including at least focus information detected at the subject region of the subject in the view; and

a tracking controller configured to;

determine at least one first region having same light information as the light information detected at the subject region from among the plurality of light measurement regions,

determine at least one second region having same focus information as the focus information detected at the subject region from among the plurality of focus detection regions,

determine reference information for tracking the subject in the view based on the at least one first region and the at least one second region, and

track the subject in the view based on the reference information.

10. The camera according to claim 9,

wherein the reference information includes information of a third region that includes the subject region, and

wherein the tracking controller is configured to:

determine the third region where the at least one first region and the at least one second region overlap, and

track the subject in the view based on the third region.

11. The camera according to claim 10,

wherein the light detector comprises an image sensor with color filter, and

wherein the view of the image corresponds to a view of an image acquired by the image sensor.

12. The camera according to claim 10, wherein

the focus detector is configured to detect a defocus amount at the plurality of focus detection regions by a phase-difference detection method.

13. A method for tracking a subject, comprising:

detecting light information based on light from a subject to be tracked at a plurality of light measurement regions in a view of an image provide by an optical system, the light information including at least light information detected at a subject region of the subject in the view;

detecting focus information at a plurality of focus detection regions in the view, the focus information including at least focus information detected at the subject region of the subject in the view;

determining at least one first region having same light information as the light information detected at the subject region from among the plurality of light measurement regions;

determining at least one second region having same focus information as the focus information of the subject from among the plurality of focus detection regions;

determining reference information for tracking the subject in the view based on the at least one first region and the at least one second region; and

tracking the subject in the view based on the reference information.

14. The method according to claim 13,

wherein the reference information includes information of a third region that includes the subject region, and

wherein the determining the reference information includes determining the subject region of the subject where the at least one first region and the at least one second region overlap.

15. The method according to claim 14,

wherein the detecting the light information includes detecting the light information from an image provided by an image sensor, and

wherein a field of the image corresponds to the field of the image provided by the optical system.

16. The method according to claim 13, further comprising:

determining whether the subject moves closer to or moves away from the optical system based on the focus information of the subject; and

changing the reference information depending on the determination of whether the subject moves closer to or moves away from the optical system,

wherein the tracking the subject in the view includes tracking the subject based on the changed reference information.

17. The method according to claim 16,

wherein the determining the reference information for tracking the subject includes determining the reference information including information of a third region that includes the subject region where the at least one first region and the at least one second region overlap, and

wherein the changing the reference information includes changing the third region in size depending on the determination of whether the subject moves closer to or moves away from the optical system.

18. The method according to claim 13,

wherein the reference information includes a hue value, and

wherein the tracking the subject in the view includes:

selecting candidates of the subject in the view based on the hue value, and

selecting the subject from among the candidates of the subject based on the focus information detected at the plurality of focus detection regions.

19. The method according to claim 13,

wherein the focus information includes a defocus amount,

wherein the light information includes at least one of color information and luminance information, and

wherein the tracking the subject in the view includes tracking the subject based on the defocus information and at least one of the color information and the luminance information.

20. A subject tracking apparatus comprising:

light detection means for detecting light information based on light from a subject to be tracked at a plurality of light measurement regions in a view of an image, the light information including at least light information detected at a subject region of the subject in the view;

focus detection means for detecting focus information at a plurality of focus detection regions in the view, the focus information including at least focus information detected at the subject region; and

tracking control means for

determining at least one first region having same light information as the light information detected at the subject region from among the plurality of light measurement regions,

determining at least one second region having same focus information as the focus information detected at the subject region from among the plurality of focus detection regions,

determining tracking information of the subject for tracking the subject in the field of view based on the at least one first region and the at least one second region, and

determining reference information for tracking the subject in the view based on the at least one first region and the at least one second region.

21. A subject tracking apparatus comprising:

an imaging device configured to capture a subject image formed by an optical system and configured to generate image information;

a focus detector configured to detect a focus state of the optical system;

a setting device configured to set a subject region including a tracked subject to be tracked;

a controller configured to detect, from a region of the image information, a first region such that a difference between color information of the first region and color information of the subject region is within a predetermined range, the controller being configured to detect, from the region of the image information, a second region such that a difference between a focus state of the second region and the focus state of the subject region detected by the focus detector is within a predetermined range, the controller being configured to track the tracked subject by using the first region and the second region.

22. The subject tracking apparatus according to claim 21, wherein

the controller is configured to track the tracked subject by using a reference image which is determined based on the first region and the second region.

23. The subject tracking apparatus according to claim 22, wherein

the controller is configured to determine the first region by using pattern matching which is based on an image of the subject region.

24. The subject tracking apparatus according to claim 21, wherein

the controller is configured to determine the second region by using a defocus amount detected by the focus detector.

25. A camera comprising:

the subject tracking apparatus according to claim 21.