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

• US 9,639,754 B2
• Filed: 05/15/2015
• Issued: 05/02/2017
• 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): Tabatabai, Abolfazl
• Application Number:
  US14/712,996
• Publication Number:
  US 20150248585A1
• Time in Patent Office: 718 Days
• Field of Search: 382103, 382107, 382236, 348169-172, 348352
• 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;

a focus detector configured to detect focus information at a plurality of focus detection regions in the view; and

a tracking controller configured to determine reference information for tracking the subject in the view based on at least one first region having substantially same light information as the light information detected at a subject region from among the plurality of light measurement regions and 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.

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;

a focus detector configured to detect focus information at a plurality of focus detection regions in the view; and

a tracking controller configured to determine reference information for tracking the subject in the view based on at least one first region having substantially same light information as the light information detected at a subject region from among the plurality of light measurement regions and 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.

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 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;

focus detection means for detecting focus information at a plurality of focus detection regions in the view; and

tracking control means for determining reference information for tracking the subject in the view based on at least one first region having substantially same light information as the light information detected at a subject region from among the plurality of light measurement regions and 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.