Optical device and method for selecting object of focus

• US 7,071,985 B1
• Filed: 12/22/1998
• Issued: 07/04/2006
• Est. Priority Date: 12/25/1997
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ohtaka, Keiji, Onoda, Hitoshi, Kadohara, Terutake
• Primary Examiner(s): Ho, Tuan
• Assistant Examiner(s): Henn, Timothy J.
• Application Number:
  US09/217,937
• Time in Patent Office: 2,751 Days
• Field of Search: 348/345, 348/348, 348/349, 348/350, 348/353, 348/355, 396/121, 396/122, 396/123
• US Class Current: 348/349
• CPC Class Codes: G02B 7/36 using image sharpness techniques , e.g. image processing techniques for generating autofocus signals image data processing per se G06T; in cameras having a solid state image sensor H04N23/67

Abstract

A camera capable of automatically detecting a main object in a sensed image. A distance distribution generation unit discriminates a plurality of areas in the sensed image on the basis of a predetermined condition, and a main object area determination unit automatically determines the main object area out of the discriminated areas. If the determined main object area is different from the area where an operator intends to focus on and the operator wishes to change the main object area, a new main object area is selected in accordance with an instruction inputted from a main object area changing unit. Then, the camera focuses on the selected main object area.

Claims

1. An optical device comprising:

a dividing unit that divides an image sensed by an image sensor into a plurality of areas;

a grouping unit that generates a focus map and groups the divided areas of the sensed image into object areas based on the generated focus map;

a main object area determination unit that determines a main object area out of the object areas grouped by said grouping unit;

a focus controller that focuses on the determined main object area using information of the focus map;

a main object area changing unit that (a) changes the main object area determined by said main object area determination unit to another one of the object areas using information of the object areas grouped by said grouping unit and (b) then causes said focus controller to focus on the new main object area using information of the focus map.

2. The optical device according to claim 1, wherein said main object area changing unit has a direction designation unit that designates a direction which is perpendicular to an optical axis of the optical device, and said main object area changing unit changes to an area next to the main object area in the direction designated by said direction designation unit as the new main object area.

3. The optical device according to claim 2, wherein said direction designation unit comprises a rotary operation member capable of rotating at least in two directions.

4. The optical device according to claim 3, wherein said direction designation unit is configured with a plurality of said rotary operation members.

5. The optical device according to claim 2, wherein said direction designation unit comprises a slide-type designation member capable of designating at least two directions.

6. The optical device according to claim 5, wherein said direction designation unit is configured with a plurality of said slide-type designation members.

7. The optical device according to claim 2, wherein said direction designation unit is a track ball.

8. The optical device according to claim 2, wherein said direction designation member is operated manually.

9. The optical device according to claim 1, wherein said grouping unit groups the divided areas in the sensed image on the basis of distances to objects included in the sensed image, and said main object area changing unit has a direction designation unit that designates a direction along an optical axis of the optical device, and said main object area changing unit changes to an area including an object a distance to which is next shorter or longer than a distance to an object included in the main object area as the new main object area depending upon the direction designated by said direction designation unit.

10. The optical device according to claim 9, wherein said direction designation unit is a focusing member of an image sensing optical system.

11. The optical device according to claim 10, wherein said direction designation unit is operated manually.

12. The optical device according to claim 1, further comprising an evaluation unit that calculates an evaluation value by performing a predetermined operation for each of the object areas grouped by said grouping unit, wherein said main object area determination unit determines the main object area on the basis of the evaluation value calculated for each of the object areas by said evaluation unit.

13. The optical device according to claim 1, wherein said main object area determination unit automatically determines the main object area.

14. The optical device according to claim 1, further comprising a priority order determination unit that determines a priority order, wherein said main object area changing unit changes the main object area in the descending order of the priority order.

15. The optical device according to claim 14, further comprising an evaluation unit that calculates an evaluation value by performing a predetermined operation for each of the object areas grouped by said grouping unit, wherein said priority order determination unit determines the priority order on the basis of the evaluation value calculated for each of the object areas by said evaluation.

16. A distance measuring point selection method comprising:

a dividing step of dividing a sensed image into a plurality of areas;

a grouping step of generating a focus map and grouping the divided areas of the sensed image into object areas based on the generated focus map;

a main object area determination step of determining a main object area out of the object areas grouped in said grouping step;

a first focus control step of focusing on the main object area determined in said main object area determination step using information of the focus map;

a main object area changing step of changing the main object area determined in said main object area determination step to another one of the object areas using information of the object area grouped in said grouping step; and

a second focus control step of changing to focus on the new main object area using information of the focus map when the main object area is changed in said main object area changing step.

17. The distance measuring point selection method according to claim 16, wherein, in said main object area changing step, an area next to the main object area in a direction designated from outside is selected as the new main object area.

18. The distance measuring point selection method according to claim 17, wherein the direction designated from outside is selected from at least two directions.

19. The distance measuring point selection method according to claim 18, wherein the direction designated from outside is perpendicular to an optical axis.

20. The distance measuring point selection method according to claim 16, wherein, in said grouping step, the divided areas in the sensed image are grouped on the basis of distances to objects included in the sensed image, and, in said main object area changing step, an area including an object a distance to which is next shorter or longer than a distance to an object included in the main object area is selected as the new main object area depending upon a direction designated from outside.

21. The distance measuring point selection method according to claim 20, wherein the direction designated from outside is an optical direction.

22. The distance measuring point selection method according to claim 16, further comprising an evaluation step of calculating an evaluation value by performing a predetermined operation for each of the object areas grouped in said grouping step, wherein, in said main object area determination step, the main object area is determined on the basis of the evaluation value calculated for each of the object areas in said evaluation step.

23. The distance measuring point selection method according to claim 16, wherein, in said main object area determination step, the main object area is automatically determined.

24. The distance measuring point selection method according to claim 16, further comprising a priority order determination step of determining a priority order, wherein, in said main object area changing step, the main object area is changed in the descending order of the priority order.

25. The distance measuring point selection method according to claim 24, further comprising an evaluation step of calculating an evaluation value by performing a predetermined operation for each of the object areas grouped in said grouping step, wherein in said priority order determination step, the priority order is determined on the basis of the evaluation value calculated for each of the object areas in said evaluation step.

26. An optical device comprising:

a grouping unit that (a) generates a focus map of a scene by determining for each of a plurality of predetermined unit areas of the scene a value which represents a distance to a content included in each predetermined unit area based on phase difference between a pair of images of the scene sensed by an image sensor, and (b) groups the predetermined unit areas of the scene into object areas based on the generated focus map;

a main object area determination unit that determines a main object area out of the object areas grouped by said grouping unit;

a focus controller that focuses on the determined main object area using information of the focus map;

a main object area changing unit that (a) changes the main object area determined by said main object area determination unit to another one of the object areas using information on the object areas grouped by said grouping unit and (b) then causes said focus controller to focus on the new main object area using information of the focus map.

27. A distance measuring point selection method comprising:

a grouping step of (a) generating a focus map of a scene by determining for each of a plurality of predetermined unit areas of the scene a value which represents a distance to a content included in each predetermined unit area based on phase difference between a pair of images of the scene sensed by an image sensor, and (b) grouping the predetermined unit areas of the scene into object areas based on the generated focus map;

a main object area determination step of determining a main object area out of the object areas grouped in said grouping step;

a first focus control step of focusing on the main object area determined in said main object area determination step using information of the focus map;

a main object area changing step of changing the main object area determined in said main object area determination step to another one of the object areas using information on the object areas grouped in said grouping step; and

a second focus control step of changing to focus on the new main object area when the main object area is changed in said main object area changing step using information of the focus map.