IMAGE CAPTURING DEVICE WITH AUTOMATIC FOCUS FUNCTION

• US 20100315526A1
• Filed: 06/10/2010
• Published: 12/16/2010
• Est. Priority Date: 06/15/2009
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Muto, Tasuku, Nakano, Kanako, Fujita, Ken, Uematsu, Daisuke
• Granted Patent: US 8,451,366 B2
• Time in Patent Office: Days
• US Class Current: 348/222.1
• CPC Class Codes: G03B 13/36 Autofocus systems
• CPC Class Codes: G03B 2217/18 Signals indicating condition of a camera member or suitability of light
• CPC Class Codes: G06T 2207/30168 Image quality inspection
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection
• CPC Class Codes: H04N 23/635 Region indicators; Field of view indicators
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

An image capturing device includes an image capturing unit, a detection unit, an area setting unit, and a focusing unit. The image capturing unit captures an image. The detection unit detects a shape of an image area of an observed subject to be focused in the captured image. The area setting unit sets one or more contrast evaluation areas according to the shape of the detected image area. The focusing unit causes the image capturing unit to focus based on image data in the set contrast evaluation areas.

Claims

1. An image capturing device comprising:

an image capturing unit configured to capture an image;

a detection unit configured to detect a shape of an image area of an observed subject to be focused in the image captured by the image capturing unit;

an area setting unit configured to set one or more contrast evaluation areas according to the shape of the image area detected by the detection unit; and

a focusing unit configured to cause the image capturing unit to focus based on image data in the contrast evaluation areas set by the area setting unit.

2. The image capturing device according to claim 1, wherein the area setting unit is configured to set the contrast evaluation areas with a same shape according to the shape of the image area.

3. The image capturing device according to claim 2, wherein the area setting unit is configured to set the contrast evaluation areas side by side.

4. The image capturing device according to claim 3, wherein the area setting unit is configured to set the contrast evaluation areas with a rectangular shape side by side.

5. The image capturing device according to claim 3, further comprising a determining unit configured to determine numbers of the contrast evaluation areas in vertical and horizontal directions according to length ratios in vertical and horizontal directions of the image area.

6. The image capturing device according to claim 5, wherein the detection unit is configured to further detect a dimension of the image area, and wherein

the determining unit is configured to determine the numbers of the contrast evaluation areas in the vertical and horizontal directions according to a dimension of an assumed contrast evaluation area set based on the shape and a dimension of the image area.

7. The image capturing unit according to claim 6, further comprising a calculating unit configured to calculate the dimension of the contrast evaluation area according to the numbers of the contrast evaluation areas in the vertical and horizontal directions determined by the determining unit.

8. The image capturing unit according to claim 7, wherein the detection unit is configured to further detect a dimension of the observed subject, and

the calculating unit is configured to calculate a dimension of the contrast evaluation area based on the shape and the dimension of the image area, and the numbers of the contrast evaluation areas in the vertical and horizontal directions determined by the determining unit.

9. The image capturing device according to claim 1, wherein the detection unit is configured to detect a dimension of the image area, and further comprises a determining unit configured to determine whether the dimension of the image area is greater than a minimum dimension of the contrast evaluation areas, and wherein

the area setting unit is configured to set the contrast evaluation areas when the dimension of the image area is greater than the minimum dimension, and sets one contrast evaluation area when the dimension of the image area is equal to or smaller than the minimum dimension.

10. The image capturing device according to claim 1, further comprising:

a subject setting unit configured to set a minimum rectangle surrounding the image area of the observed subject as an assumed shape of the image area of the observed subject;

an area determining unit configured to determine whether the contrast evaluation areas include the image area of the observed subject at a ratio equal to or greater than a predetermined ratio based on the assumed shape of the image area; and

a removal unit configured to remove a contrast evaluation area determined as not including the image area of the observed subject at a ratio equal to or greater than the predetermined ratio from an evaluation target.

11. The image capturing device according to claim 1, wherein the area setting unit is configured to set a contrast evaluation area overlapping with an edge portion of the image area of the observed subject.

12. The image capturing device according to claim 1, wherein

the detection unit is configured to sequentially detect the shape of the image area of the observed subject;

and

the area setting unit is configured to set the contrast evaluation areas according to the shape of the image area of the observed subject sequentially detected by the detection module.

13. The image capturing device according to claim 1, wherein the focusing control unit is configured to cause the image capturing unit to focus by adopting image data in a contrast evaluation area which is included in the contrast evaluation areas, in which detection precision of a contrast gradient of image data in each of the evaluation areas is equal to or greater than a predetermined value, and which includes a peak contrast in a distance closest to the image capturing device.

14. The image capturing device according to claim 1, wherein the area setting unit is configured to set the contrast evaluation area by giving priority to a vertical direction over a horizontal direction of the image area of the observed subject.

15. An image capturing method for an image capturing unit, the method comprising:

detecting a shape of an image area of an observed subject to be focused in the image captured by the image capturing unit;

setting one or more contrast evaluation areas according to the detected shape of the image area; and

causing the image capturing unit to focus based on image data in the set contrast evaluation areas.

16. A non-transitory computer readable medium storing a computer program for controlling an image capturing unit, the program comprising:

detecting a shape of an image area of an observed subject to be focused in the image captured by the image capturing unit;

setting one or more contrast evaluation areas according to the detected shape of the image area; and

causing the image capturing unit to focus based on image data in the set contrast evaluation areas.