IMAGE PROCESSING APPARATUS, IMAGE PROCESSING METHOD, IMAGE PROCESSING PROGRAM, AND IMAGE PICKUP APPARATUS ACQUIRING A FOCUSING DISTANCE FROM A PLURALITY OF IMAGES

• US 20170163876A1
• Filed: 02/21/2017
• Published: 06/08/2017
• Est. Priority Date: 05/17/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takahashi, Takahiro
• Granted Patent: US 10,021,290 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 18/22 Matching criteria, e.g. proximity measures
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: G06T 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes
• CPC Class Codes: H04N 23/676 Bracketing for image capture at varying focusing conditions
• CPC Class Codes: H04N 23/959 by adjusting depth of field during image capture, e.g. maximising or setting range based on scene characteristics

Abstract

An image processing apparatus that acquires a focusing distance from a plurality of images each having different degrees of blur, comprises a misalignment detection unit that detects misalignment among the plurality of images; a distance information acquisition unit that acquires, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images; and a reliability information acquisition unit that creates, based on the detected misalignment, reliability information, which is information to indicate reliability of the focusing distance acquired for each area, wherein the distance information acquisition unit changes the acquired distance information based on the reliability information.

Claims

1. An image processing apparatus that acquires a focusing distance from a plurality of images each having different degrees of blur, comprising:

a misalignment detection unit that detects misalignment among the plurality of images;

a distance information acquisition unit that acquires, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images; and

a reliability information acquisition unit that creates, based on the detected misalignment, reliability information, which is information to indicate reliability of the focusing distance acquired for each area, wherein

the distance information acquisition unit changes the acquired distance information based on the reliability information.

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

for an area of which the reliability is lower than a predetermined value, the distance information acquisition unit uses a focusing distance corresponding to another area of which the reliability is higher than the predetermined value, instead of the acquired focusing distance.

3. The image processing apparatus according to claim 2, wherein

the distance information acquisition unit determines a correction area where brightness or hue of pixels therein is in a predetermined range, and for an area of which the reliability is lower than the predetermined value, uses a focusing distance corresponding to another area belonging to a same correction area to which this area belongs instead of the acquired focusing distance.

4. The image processing apparatus according to claim 1, wherein

the reliability information acquisition unit acquires a difference between misalignment in a target area and average misalignment in a plurality of surround area of the target area, and if the difference is great, sets a lower reliability for the target area compared with a case when the difference is small.

5. The image processing apparatus according to claim 1, wherein

the reliability information acquisition unit creates the reliability information further based on a frequency characteristic of a more focused image or a brightness value of pixels therein among the plurality of images photographed.

6. The image processing apparatus according to claim 5, wherein

if a spatial frequency of a target area is low, the reliability information acquisition unit sets a lower reliability for the target area compared with a case when the spatial frequency is high.

7. The image processing apparatus according to claim 1, wherein

the reliability information acquisition unit creates the reliability information further based on a difference among the plurality of images photographed.

8. The image processing apparatus according to claim 1, further comprising

a depth of field control unit that blurs a more focused image among the plurality of images photographed, using the distance information acquired by the distance information acquisition unit.

9. The image processing apparatus according to claim 8, wherein

the depth of field control unit decreases a blurring amount for an area of which the reliability is low compared with a case when the reliability is high.

10. An image pickup apparatus comprising:

an imaging unit; and

the image processing apparatus according to claim 1.

11. An image processing method used by an image processing apparatus that acquires a focusing distance from a plurality of images each having different degrees of blur, the method comprising the steps of:

detecting misalignment among the plurality of images;

acquiring, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images;

creating, based on the detected misalignment, reliability information, which is information to indicate reliability of the focusing distance acquired for each area; and

changing the acquired distance information based on the reliability information.

12. A non-transitory storage medium recording an image processing program for causing an image processing apparatus, which acquires a focusing distance from a plurality of images each having different degrees of blur, to execute the steps of:

detecting misalignment among the plurality of images;

acquiring, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images;

creating, based on the detected misalignment, reliability information, which is information to indicate reliability of the focusing distance acquired for each area; and

changing the acquired distance information based on the reliability information.