Image capturing apparatus to prevent image blurring and control method therefor

• US 8,319,842 B2
• Filed: 11/10/2008
• Issued: 11/27/2012
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shibata, Masahiro
• Primary Examiner(s): VILLECCO, JOHN M
• Application Number:
  US12/267,940
• Publication Number:
  US 20090153680A1
• Time in Patent Office: 1,478 Days
• Field of Search: 348/208.1, 348/208.6, 348/208.99, 348/208.4
• US Class Current: 348/208.6
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6845 by combination of a plurality of images sequentially taken
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20

Abstract

An image capturing apparatus includes a motion vector detection unit which detects a motion vector on the basis of the correlation between image signals continuously captured by an image capturing unit, a reliability evaluation value calculation unit which calculates the reliability evaluation value of the motion vector detected by the motion vector detection unit, a blurring correction amount determination unit which determines the image blurring correction amount on the basis of the motion vector detected by the motion vector detection unit, a correction amount reduction unit which reduces the image blurring correction amount on the basis of the reliability evaluation value calculated by the reliability evaluation value calculation unit, and a blurring correction unit which corrects image blurring on the basis of the image blurring correction amount reduced by the correction amount reduction unit.

Claims

1. An image capturing apparatus comprising:

an image capturing unit which captures an object image formed by an imaging optical system and outputs an image signal;

a motion vector detection unit which detects a local motion vector on the basis of correlation between image signals continuously captured by said image capturing unit;

a motion vector determination unit configured to determine a motion vector of an entire image based on the detected motion vectors;

a reliability evaluation value calculation unit which determines whether every local motion vector is valid or invalid, and which calculates a reliability evaluation value of the motion vector of the entire image based on the valid local motion vectors;

a reduction rate determination unit configured to determine a reduction rate based on the reliability evaluation value;

a blurring correction amount determination unit configured to determine an image blurring correction amount by correcting a correction amount calculated based on the motion vector of the entire image, based on the reduction rate and

a blurring correction unit which corrects image blurring on the basis of the image blurring correction amount.

2. The apparatus according to claim 1, wherein a frame of said image capturing unit is divided into a plurality of blocks, said motion vector detection unit detects a motion vector of each divided block as the local motion vector, and said reliability evaluation value calculation unit calculates, as the reliability evaluation value of the motion vector, a ratio of local motion vectors determined to be valid to local motion vectors of all blocks.

3. The apparatus according to claim 1, wherein said reduction rate determination unit decreases reduction of the image blurring correction amount as the reliability evaluation value is larger.

4. An image capturing apparatus comprising:

an image capturing unit which captures an object image formed by an imaging optical system capable of zooming, and outputs an image signal;

a motion vector detection unit which detects local motion vectors on the basis of correlation between image signals continuously captured by said image capturing unit;

a motion vector determination unit configured to determine a motion vector of an entire image based on the detected motion vectors;

a reliability evaluation value calculation unit which determines whether every local motion vector is valid or invalid, and which calculates a reliability evaluation value of the motion vector of the entire image based on the valid local motion vectors;

a reduction rate determination unit configured to determine a reduction rate based on the reliability evaluation value and a zoom position of the imaging optical system;

a blurring correction amount determination unit configured to determine an image blurring correction amount by correcting a correction amount calculated based on the motion vector of the entire image, based on the reduction rate; and

a blurring correction unit which corrects image blurring on the basis of the image blurring correction amount.

5. The apparatus according to claim 4, wherein a frame of said image capturing unit is divided into a plurality of blocks, said motion vector detection unit detects a motion vector of each divided block as the local motion vector, and said reliability evaluation value calculation unit calculates, as the reliability evaluation value of the motion vector, a ratio of local motion vectors determined to be valid to local motion vectors of all blocks.

6. The apparatus according to claim 4, wherein said reduction rate determination unit decreases the reduction rate as the reliability evaluation value is larger.

7. The apparatus according to claim 4, wherein when the reliability evaluation value remains unchanged, said reduction rate determination unit increases the reduction rate as the zoom position of the imaging optical system comes close to a telephoto end.

8. A method of controlling an image capturing apparatus having an image capturing unit which captures an object image formed by an imaging optical system and outputs an image signal, the method comprising:

detecting local motion vector on the basis of correlation between image signals continuously captured by the image capturing unit;

determining a motion vector of an entire image based on the detected motion vectors;

determining whether every motion vector is valid or invalid;

calculating a reliability evaluation value of the motion vector of the entire image based on the valid local motion vectors;

determining a reduction rate based on the reliability evaluation value;

determining an image blurring correction amount by correcting a correction amount calculated based on the motion vector of the entire image, based on the reduction rate; and

correcting image blurring on the basis of the image blurring correction amount.

10. A non-transitory storage medium storing a program which causes a computer to execute a control method defined in claim 8.

9. A method of controlling an image capturing apparatus having an image capturing unit which captures an object image formed by an imaging optical system capable of zooming, and outputs an image signal, the method comprising:

detecting local motion vectors on the basis of correlation between image signals continuously captured by the image capturing unit;

determining a motion vector of an entire image based on the detected motion vectors;

determining whether every local motion vector is valid or invalid;

calculating a reliability evaluation value of the motion vector of the entire image based on both the valid local motion vectors;

determining a reduction rate based on the reliability evaluation value and a zoom position of the imaging optical system;

determining an image blurring correction amount by correcting a correction amount calculated based on the motion vector of the entire image, based on the reduction rate; and

correcting image blurring on the basis of the image blurring correction amount.

11. A non-transitory storage medium storing a program which causes a computer to execute a control method defined in claim 9.

12. An image capturing apparatus comprising:

an image capturing unit which captures an object image formed by an imaging optical system and outputs an image signal;

a motion vector detection unit which detects a motion vector on the basis of correlation between image signals continuously captured by said image capturing unit;

a reliability evaluation value calculation unit which calculates a reliability evaluation value of the motion vector;

a blurring correction amount determination unit which determines an image blurring correction amount on the basis of the motion vector;

a correction amount changing unit which changes the image blurring correction amount in accordance with an amplification rate determined based on the reliability evaluation value, wherein the correction amount changing unit changes the image blurring correction amount such that the image blurring correction amount becomes small as the reliability evaluation value becomes small; and

a blurring correction unit which corrects image blurring on the basis of the image blurring correction amount.

13. The apparatus according to claim 12,

wherein the amplification rate also determines based on a zoom position of the imaging optical system,

wherein the correction amount changing unit changes the image blurring correction amount such that the blurring correction amount becomes small as the zoom position of the imaging optical system becomes telephoto side.

14. The apparatus according to claim 12, wherein a frame of said image capturing unit is divided into a plurality of blocks, said motion vector detection unit detects a motion vector of each divided block, and said reliability evaluation value calculation unit calculates, as the reliability evaluation value of the motion vector, a ratio of motion vectors determined to be valid to motion vectors of all blocks that are detected by said motion vector detection unit.