Image pickup apparatus having auto-focus control and image pickup method

• US 20040004670A1
• Filed: 03/12/2003
• Published: 01/08/2004
• Est. Priority Date: 03/14/2002
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yamashita, Yuichiro
• Granted Patent: US 7,423,686 B2
• Time in Patent Office: Days
• US Class Current: 348/345
• 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 23/675 comprising setting of focusing regions

Abstract

To track a region of interest (“ROI”) such as, for example, in a viewfinder of a camera, both the location and distance of a point in the ROI are estimated for a time in the future, based on actual measurements of locations and distances of the point at the present and in the past. Focus is controlled so as to focus on the point of interest based on the estimate of the future location and distance.

Claims

1. An image pickup apparatus comprising:

tracking means for automatically tracking a predetermined point of interest;

estimating means for, based on each information on locations and distances of the point of interest at present, n, and in past, n−

1, estimating a location and a distance of the point of interest in future, n+1; and

controlling means for controlling to focus on the point of interest based on an output of said estimating means.

2. The apparatus according to claim 1, wherein said controlling means controls to focus on the point of interest by using a signal from at least a part of an area image sensor.

3. The apparatus according to claim 1, wherein said controlling means controls to focus on the point of interest by using a signal from at least a part of a focus sensor.

4. The apparatus according to claim 1, wherein said controlling means controls to focus on the point of interest by using a signal front at least a part of a light metering sensor.

5. The apparatus according to claim 2, wherein said controlling means discards signals of a region which is not used for the tracking and for reading out at high speed a region to be tracked for the point of interest.

6. The apparatus according to claim 5, wherein said control means discards the signal of non-neighboring of the point of interest.

7. The apparatus according to claim 1, further comprising correcting means for correcting errors based on temporal continuity of the distance information.

8. The apparatus according to claim 1, further comprising correcting means for correcting errors based on spatial continuity of motion of the point.

9. The apparatus according to claim 1, wherein said controlling means controls by using object color information as tracking information.

10. The apparatus according to claim 1, wherein said controlling means controls by using object illumination information.

11. The apparatus according to claim 1, wherein said controlling means detects motion of the point of interest using a time differential component and a space differential component of illumination information around of the point of interest.

12. The apparatus according to claim 1, wherein said controlling means estimates the motion of the point of interest by using template matching.

13. The apparatus according to claim 1, wherein said controlling means estimates the motion of the point of interest by using Kalman Filter.

14. The apparatus according to claim 1, further comprising specifying means for specifying the point of interest on a finder or a preview monitor;

and

calculating means for calculating to select a region of interest based on the specified point of interest.

15. A method for an image pickup, comprising the steps of:

automatically tracking a point of interest;

based on each information on lotions and distances of the point of interest at present, n, and in past, n−

1, estimating both a location and a distance of the point of interest in future, n+1; and

controlling to focus on the point of interest based on the estimated location and distance of the point.

16. The method according to claim 15, wherein a signal from at least a part of an area image sensor is used for controlling.

17. The method according to claim 15, further comprising the step of correcting errors based on temporal continuity of the distance information of the point of interest.

18. The method according to claim 15, further comprising the step of correcting errors based on spatial continuity of motion of the point of interest.

19. The method according to claim 15, further comprising the steps of:

specifying the point of interest on a finder or a preview monitor; and

calculating to select a region of interest based on the specified point of interest.

20. A computer readable medium having recorded thereon a computer program implementing the steps of defined in claim 15.