Focus adjustment apparatus and focus adjustment method

• US 8,107,806 B2
• Filed: 08/11/2010
• Issued: 01/31/2012
• Est. Priority Date: 08/18/2009
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Uenishi, Masaaki
• Primary Examiner(s): BLACKMAN, ROCHELLE ANN J
• Application Number:
  US12/854,403
• Publication Number:
  US 20110044675A1
• Time in Patent Office: 538 Days
• Field of Search: 396/95, 396123-125, 348/345, 348/348, 348/349, 348/352, 348354-356, 250/201.2, 250/201.4, 250/201.7, 250/201.8
• US Class Current: 396/95
• CPC Class Codes: G02B 7/102 controlled by a microcomputer cameras with interchangeable lenses G03B17/14
• CPC Class Codes: G03B 13/34 Power focusing
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

A focus adjustment apparatus includes an imaging unit configured to capture an object image input via a focus lens to output image data, a focus adjustment unit configured to perform focus adjustment by controlling a position of the focus lens based on the image data, a motion detection unit configured to detect a motion of the object image based on the image data, and a control unit configured to control the focus adjustment unit to perform a first focus adjustment operation if motion of the object image is not detected by the motion detection unit, and to control the focus adjustment unit to perform a second focus adjustment operation different from the first focus adjustment operation if motion of the object image is detected by the motion detection unit.

Claims

1. A focus adjustment apparatus comprising:

an imaging unit configured to capture an object image input via a focus lens to output image data;

a focus adjustment unit configured to perform focus adjustment by controlling a position of the focus lens based on focus evaluation value of the image data;

a motion detection unit configured to detect a motion of the object image based on the image data; and

a control unit configured to control the focus adjustment unit to perform a first focus adjustment operation if it is not satisfying a predetermined condition, and to control the focus adjustment unit to perform a second focus adjustment operation different from the first focus adjustment operation if it is satisfying the predetermined condition,

wherein the predetermined condition includes a condition that motion of the object image is detected by the motion detection unit, and

wherein the control unit controls the focus adjustment unit so as to, in the first focus adjustment operation, determine movement direction of the focus lens according to a comparison result of current focus evaluation value and previous focus evaluation value and move the focus lens to the determined movement direction, and in the second focus adjustment operation, to predict a position of the object according to a plurality of in-focus positions which are previously detected and move the focus lens within a movement area which is set based on the predicted position of the object.

2. The focus adjustment apparatus according to claim 1, wherein the control unit controls the focus adjustment unit to make a movement amount of the focus lens per unit time in the second focus adjustment operation larger than in the first focus adjustment operation.

3. The focus adjustment apparatus according to claim 1, wherein the motion detection unit detects the motion of the object image by detecting a face of an object from the image data and determining a change in the face.

4. The focus adjustment apparatus according to claim 3, wherein the change in the face includes a change in position or size of the face of the object.

5. The focus adjustment apparatus according to claim 4, wherein the motion detection unit detects the motion of the object image if the position or size of the face of the object is consecutively changed in a same direction for a predetermined amount or more a predetermined number of times or more.

6. The focus adjustment apparatus according to claim 1, wherein the motion detection unit does not detect the motion of the object image during an optical zoom operation or electronic zoom operation.

7. The focus adjustment apparatus according to claim 1, wherein if a luminance of the image data is lower than or equal to a predetermined value, the control unit controls the focus adjustment unit not to perform the second focus adjustment operation but to perform the first focus adjustment operation.

8. The focus adjustment apparatus according to claim 1, further comprising a display control unit configured to, based on a result of motion detection of the object image by the motion detection unit, cause information indicating whether the object is moving to be displayed on a screen.

9. A method comprising:

capturing an object image input via a focus lens to output image data;

controlling a position of the focus lens based on focus evaluation value the image data;

detecting a motion of the object image based on image data; and

performing a first focus adjustment operation if it is not satisfying a predetermined condition, and performing a second focus adjustment operation if it is satisfying the predetermined condition,

wherein the predetermined condition includes a condition that motion of the object image is detected, and

wherein the controlling controls the performing the first focus adjustment operation includes determining movement direction of the focus lens according to a comparison result of current focus evaluation value and previous focus evaluation value and moving the focus lens to the determined movement direction, and

wherein the controlling controls the performing the second focus adjustment operation includes predicting a position of the object according to a plurality of in-focus positions which are previously detected and moving the focus lens within a movement area which is set based on the predicted position of the object.

10. The method according to claim 9, further comprising controlling the focus adjustment unit to make a movement amount of the focus lens per unit time in the second focus adjustment operation larger than in the first focus adjustment operation.

11. The method according to claim 9, further comprising detecting the motion by detecting a face of an object from the image data and determining a change in the face.

12. The method according to claim 11, wherein the change in the face includes a change in position or size of the face.

13. The method according to claim 12, further comprises detecting the motion if the position or size is changed in a same direction for a predetermined amount or more a predetermined number of times or more.

14. The method according to claim 9, further comprising performing the first focus adjustment operation if a luminance of the image data is lower than or equal to a predetermined value.

15. The method according to claim 9, further comprising causing information indicating whether the object is moving to be displayed on a screen a display, based on a result of motion detection of the object image.