Image capture apparatus and control method therefor

• US 9,277,111 B2
• Filed: 05/07/2013
• Issued: 03/01/2016
• Est. Priority Date: 05/18/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kawarada, Masahiro
• Primary Examiner(s): Natnael, Paulos M
• Application Number:
  US13/888,424
• Publication Number:
  US 20130307993A1
• Time in Patent Office: 1,029 Days
• Field of Search: 348/169, 348/207.99, 348/222.1
• US Class Current: 1/1
• 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 23/635 Region indicators; Field of view indicators
• CPC Class Codes: H04N 23/672 based on the phase difference signals
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

A specific subject region is detected, and if a focus detection area that is encompassed in the specific subject region is present, focus detection is performed on that focus detection area. This makes it possible to reduce the influence of a conflict between far and near subjects and reduce the amount of time required for focus detection in an image capture apparatus and in a control method therefor, the image capture apparatus being for performing automatic focus detection based on contrast evaluation values for a plurality of focus detection areas that are each located at a fixed position and each has a fixed size.

Claims

1. An image capture apparatus comprising:

a focus detection unit configured to perform focus detection based on a contrast evaluation value for an image included in a focus detection area;

a subject detection unit configured to detect a region of a specific subject from an image; and

a selection unit configured to select at least one focus detection area, on which focus detection is performed by the focus detection unit, from among a plurality of preset focus detection areas each being located at a fixed position and having a fixed size,

wherein the selection unit is configured to, when the region of the specific subject is detected and a focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, select the focus detection area that is encompassed by the region of the specific subject, and when the region of the specific subject is detected and no focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, select at least one predetermined focus detection area from among the plurality of preset focus detection areas.

2. The image capture apparatus according to claim 1, wherein

the subject detection unit is configured to further detect a region of another subject that is considered to be located at the same distance as the specific subject, and

the selection unit is configured to, when the region of the other subject is detected and a focus detection area that is encompassed by the region of the other subject is present among the plurality of preset focus detection areas, further select the focus detection area that is encompassed by the region of the other subject, and when the region of the other subject is detected and neither a focus detection area that is encompassed by the region of the specific subject nor a focus detection area that is encompassed by the region of the other subject is present among the plurality of preset focus detection areas, select at least one predetermined focus detection area from among the plurality of preset focus detection areas.

3. The image capture apparatus according to claim 2, wherein the subject detection unit is configured to detect a face of a person as the specific subject and a body of the person as the other subject.

4. The image capture apparatus according to claim 1, further comprising a determination unit configured to determine one of the at least one focus detection area selected by the selection unit as a focus detection area that is focused on, based on a focus detection result for the at least one focus detection area.

5. The image capture apparatus according to claim 1, wherein the focus detection unit is configured to, when a focus detection area that is encompassed by the region of the specific subject is not yet set and a focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, reset a result of focus detection that has been performed without any focus detection area that is encompassed by the region of the specific subject being set, and perform focus detection based on a contrast evaluation value for an image included in the focus detection area that is encompassed by the region of the specific subject and that is selected by the selection unit.

6. A method for controlling an image capture apparatus, comprising:

a subject detection step of detecting a region of a specific subject from an image;

a selection step of selecting a focus detection area on which focus detection is performed, from among a plurality of preset focus detection areas each being located at a fixed position and having a fixed size; and

a focus detection step of performing focus detection based on a contrast evaluation value for an image included in the focus detection area selected in the selection step,

wherein in the selection step, when the region of the specific subject is detected in the subject detection step and a focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, the focus detection area that is encompassed by the region of the specific subject is selected, and when the region of the specific subject is detected in the subject detection step and no focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection area, at least one predetermined focus detection area is selected from among the plurality of preset focus detection areas.

7. An image capture apparatus comprising:

a focus detection unit configured to set a plurality of focus detection areas each being located at a fixed position and having a fixed size, and for the focus detection areas, detect an in-focus distance based on a contrast evaluation value for an image;

a subject detection unit configured to detect a region of a specific subject from an image;

a determination unit configured to determine a representative in-focus distance based on the in-focus distances detected by the focus detection unit; and

an in-focus display unit configured to, when at least one of the in-focus distances, detected for focus detection areas that include the region of the specific subject, is within a depth of field of the representative in-focus distance, provide a display indicating that all of the focus detection areas that include the region of the specific subject are in focus, even if any of the focus detection areas that include the region of the specific subject has an in-focus distance not within the depth of field of the representative in-focus distance.

8. The image capture apparatus according to claim 7, wherein

the subject detection unit is configured to further detect a region of another subject that is considered to be located at the same distance as the specific subject, and

the in-focus display unit is configured to, when at least one of the in-focus distances, detected for focus detection areas that include the region of the other subject, is within a depth of field of the representative in-focus distance, provide a display indicating that all of the focus detection areas that include the region of the specific subject are in focus, even if none of the focus detection areas that include the region of the specific subject has an in-focus distance within the depth of field of the representative in-focus distance.

9. The image capture apparatus according to claim 8, wherein the subject detection unit is configured to detect a face of a person as the specific subject and a body of the person as the other subject.

10. A method for controlling an image capture apparatus, comprising:

a focus detection step of setting a plurality of focus detection areas each being located at a fixed position and having a fixed size, and for the focus detection areas, detecting an in-focus distance based on a contrast evaluation value for an image;

a subject detection step of detecting a region of a specific subject from an image;

a determination step of determining a representative in-focus distance based on the in-focus distances detected in the focus detection step; and

an in-focus display step of, when at least one of the in-focus distances, detected for focus detection areas that include the region of the specific subject, is within a depth of field of the representative in-focus distance, providing a display indicating that all of the focus detection areas that include the region of the specific subject are in focus, even if any of the focus detection areas that include the region of the specific subject has an in-focus distance not within the depth of field of the representative in-focus distance.

11. An image capture apparatus comprising:

a focus detection unit configured to detect an in-focus distance of a focus detection area based on a contrast evaluation value for an image included in the focus detection area;

a subject detection unit configured to detect a region of a specific subject from an image;

a selection unit configured to select a focus detection area, for which an in-focus distance is detected by the focus detection unit, from among a plurality of preset focus detection areas each being located at a fixed position and having a fixed size;

a determination unit configured to determine a representative in-focus distance based on an in-focus distance detected by the focus detection unit; and

an in-focus display unit configured to provide a display indicating that a focus detection area whose in-focus distance detected by the focus detection unit is within a depth of field of the representative in-focus distance is in focus among the plurality of preset focus detection areas,

wherein the selection unit is configured to, when the region of the specific subject is detected and a focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, select the focus detection area that is encompassed by the region of the specific subject, and when no focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, select at least one predetermined focus detection area from among the plurality of preset focus detection areas, and

the in-focus display unit is configured to, when a focus detection area that includes the region of the specific subject is present among a focus detection area whose in-focus distance detected by the focus detection unit is within a depth of field of the representative in-focus distance, provide a display indicating that every focus detection area that includes the region of the specific subject is in focus among the plurality of preset focus detection areas.

12. The image capture apparatus according to claim 11, wherein

the subject detection unit is configured to further detect a region of another subject that is considered to be located at the same distance as the specific subject, and

the selection unit is configured to, when the region of the other subject is detected and a focus detection area that is encompassed by the region of the other subject is present among the plurality of preset focus detection areas, further select the focus detection area that is encompassed by the region of the other subject, and when the region of the other subject is detected and neither a focus detection area that is encompassed by the region of the specific subject nor a focus detection area that is encompassed by the region of the other subject is present among the plurality of preset focus detection areas, select at least one predetermined focus detection area from among the plurality of preset focus detection areas.

13. The image capture apparatus according to claim 11, wherein

the subject detection unit is configured to further detect a region of another subject that is considered to be located at the same distance as the specific subject, and

the in-focus display unit is configured to, when a focus detection area that includes the region of the other subject is present among a focus detection area whose in-focus distance detected by the focus detection unit is within a depth of field of the representative in-focus distance, provide a display indicating that every focus detection area that includes the region of the specific subject is in focus among the plurality of preset focus detection areas, even if no focus detection area that includes the region of the specific subject is present among the focus detection area whose in-focus distance detected by the focus detection unit is within a depth of field of the representative in-focus distance.

14. The image capture apparatus according to claim 12, wherein the subject detection unit is configured to detect a face of a person as the specific subject and a body of the person as the other subject.

15. A method for controlling an image capture apparatus, comprising:

a subject detection step of detecting a region of a specific subject from an image;

a selection step of selecting a focus detection area for which an in-focus distance is detected, from among a plurality of preset focus detection areas each being located at a fixed distance and having a fixed size;

a focus detection step of detecting an in-focus distance of the focus detection area selected in the selection step, based on a contrast evaluation value for an image included in the focus detection area;

a determination step of determining a representative in-focus distance based on the in-focus distance detected in the focus detection step; and

an in-focus display step of providing a display indicating that a focus detection area whose in-focus distance detected in the focus detection step is within a depth of field of the representative in-focus distance is in focus among the plurality of preset focus detection areas,

wherein in the selection step, when the region of the specific subject is detected and a focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, the focus detection area that is encompassed by the region of the specific subject is selected, and when the region of the specific subject is detected and no focus detection area that is encompassed by the region of the specific subject is present among the plurality of preset focus detection areas, at least one predetermined focus detection area is selected from among the plurality of preset focus detection areas, and

in the in-focus display step, when a focus detection area that includes the region of the specific subject is present among a focus detection area whose in-focus distance detected in the focus detection step is within a depth of field of the representative in-focus distance, a display is provided to indicate that every focus detection area that includes the region of the specific subject is in focus among the plurality of preset focus detection areas.