IMAGE CAPTURING APPARATUS, IMAGE CAPTURING METHOD, AND PROGRAM

• US 20080273099A1
• Filed: 04/28/2008
• Published: 11/06/2008
• Est. Priority Date: 05/01/2007
• Status: Active Grant

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Ono, Hiroaki
• Granted Patent: US 8,537,264 B2
• Time in Patent Office: Days
• US Class Current: 348/241
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 23/675 comprising setting of focusing regions

Abstract

An image capturing apparatus includes an image pickup unit including an image pickup element that captures a plurality of colors in ranges of visible and invisible light incoming through an image capturing lens, a pixel value calculating unit that calculates a pixel value of each pixel regarding at least one of the captured colors, a contrast value calculating unit that calculates a contrast value for each color based on the calculated pixel values, a correction value calculating unit that calculates a focus correction value for a distance from a current position of the image capturing lens to a focus position based on a temporal change in the calculated contrast values of the at least one color, and an image capturing lens driving unit that drives the image capturing lens based on the calculated focus correction value.

Claims

1. An image capturing apparatus comprising:

image pickup means including an image pickup element configured to capture, in a unit of pixels, a plurality of colors in ranges of visible and invisible light incoming through an image capturing lens;

pixel value calculating means configured to calculate a pixel value of each pixel regarding at least one of the colors captured by the image pickup means;

contrast value calculating means configured to calculate a contrast value for each of the at least one color on the basis of the pixel values calculated by the pixel value calculating means;

correction value calculating means configured to calculate a focus correction value for a distance from a current position of the image capturing lens to a focus position of the image capturing lens on the basis of a temporal change in the contrast values of the at least one color calculated by the contrast value calculating means; and

image capturing lens driving means configured to drive the image capturing lens on the basis of the focus correction value calculated by the focus correction value calculating means.

2. The apparatus according to claim 1, wherein the pixel value calculating means calculates, for each pixel, a luminance value, including the visible light and the invisible light, as a pixel value, and

wherein the contrast value calculating means calculates the contrast value on the basis of the luminance values calculated by the pixel value calculating means, and

wherein the focus correction value calculating means calculates the focus correction value for the distance from the current position of the image capturing lens to the focus position of the image capturing lens on the basis of the temporal change in the contrast values calculated by the contrast value calculating means.

3. The apparatus according to claim 1, wherein

the pixel value calculating means includes

visible light value calculating means configured to calculate, for each pixel, a luminance value of visible light as a visible light value, and

invisible light value calculating means configured to calculate, for each pixel, a luminance value of invisible light as an invisible light value, and

wherein the contrast value calculating means includes

visible light contrast calculating means configured to calculate a visible light contrast value regarding the visible light values calculated by the visible light value calculating means, and

invisible light contrast calculating means configured to calculate an invisible light contrast value regarding the invisible light values calculated by the invisible light value calculating means, and

wherein the focus correction value calculating means calculates the focus correction value for the distance from the current position of the image capturing lens to the focus position of the image capturing lens on the basis of the temporal change in the visible light contrast values and the invisible light contrast values.

4. The apparatus according to claim 3, further comprising:

visible light S/N ratio calculating means configured to calculate an S/N ratio of the visible light contrast value calculated by the visible light contrast value calculating means; and

invisible light S/N ratio calculating means configured to calculate an S/N ratio of the invisible light contrast value calculated by the invisible light contrast value calculating means, wherein

the focus correction value calculating means compares the S/N ratio of the visible light contrast value with the S/N ratio of the invisible light contrast value, selects the contrast value having a larger S/N ratio as a contrast value suitable for calculation of the focus correction value, and calculates the focus correction value for the distance from the current position of the image capturing lens to the focus position of the image capturing lens on the basis of a temporal change in the contrast values suitable for calculation of the focus correction value.

5. The apparatus according to claim 3, further comprising:

contrast value combining means configured to combine the visible light contrast value and the invisible light contrast value to generate a combined contrast value, wherein

the focus correction value calculating means calculates the focus correction value for the distance from the current position of the image capturing lens to the focus position of the image capturing lens on the basis of a temporal change in the combined contrast values.

6. The apparatus according to claim 5, wherein the contrast value combining means combines the visible light contrast value and the invisible light contrast value at a combination ratio based on both of the contrast values to generate the combined contrast value, and

wherein the focus correction value calculating means calculates, according to the combination ratio, the focus correction value for the distance from the current position of the image capturing lens to the focus position of the image capturing lens on the basis of the temporal change in the combined contrast values.

7. The apparatus according to claim 1, wherein the pixel value calculating means calculates, for each pixel, a luminance value of infrared light and a luminance value of ultraviolet light as an infrared light value and an ultraviolet light value, respectively, and

wherein the contrast value calculating means calculates a contrast value for each of the visible light values, the infrared light values, and the ultraviolet light values calculated by the pixel value calculating means, and

wherein the focus correction value calculating means calculates the focus correction value for the distance from the current position of the image capturing lens to the focus position of the image capturing lens on the basis of temporal changes in the contrast values of the visible light values, the infrared light values, and the ultraviolet light values calculated by the contrast value calculating means.

8. The apparatus according to claim 1, further comprising:

auxiliary light irradiating means configured to irradiate light of a color, in the visible and invisible light ranges, suitable for calculation of the contrast value onto a subject; and

auxiliary light irradiation control means configured to control irradiation of auxiliary light performed by the auxiliary light irradiating means.

9. The apparatus according to claim 8, wherein the auxiliary light irradiation control means controls the auxiliary light irradiating means to irradiate light, selected from the visible light, the infrared light, and the ultraviolet light, suitable for calculation of the contrast value onto a subject.

10. An image capturing method comprising the steps of:

capturing, in a unit of pixels, a plurality of colors in ranges of visible and invisible light incoming through an image capturing lens;

calculating a pixel value of each pixel regarding at least one of the captured colors;

calculating, for each of the at least one color, a contrast value on the basis of the calculated pixel values of the corresponding color;

calculating a focus correction value for a distance from a current position of the image capturing lens to a focus position of the image capturing lens on the basis of a temporal change in the calculated contrast values of the at least one color; and

driving the image capturing lens on the basis of the calculated focus correction value.

11. A program allowing a computer to execute a method, the method comprising the steps of:

capturing, in a unit of pixels, a plurality of colors in ranges of visible and invisible light incoming through an image capturing lens;

calculating a pixel value of each pixel regarding at least one of the captured colors;

calculating, for each of the at least one color, a contrast value on the basis of the calculated pixel values of the corresponding color;

calculating a focus correction value for a distance from a current position of the image capturing lens to a focus position of the image capturing lens on the basis of a temporal change in the calculated contrast values of the at least one color; and

driving the image capturing lens on the basis of the calculated focus correction value.

12. A program-storing medium having a program stored thereon, the program allowing a computer to execute a method, the method comprising the steps of:

capturing, in a unit of pixels, a plurality of colors in ranges of visible and invisible light incoming through an image capturing lens;

calculating a pixel value of each pixel regarding at least one of the captured colors;

calculating, for each of the at least one color, a contrast value on the basis of the calculated pixel values of the corresponding color;

calculating a focus correction value for a distance from a current position of the image capturing lens to a focus position of the image capturing lens on the basis of a temporal change in the calculated contrast values of the at least one color; and

driving the image capturing lens on the basis of the calculated focus correction value.

13. An image capturing apparatus comprising:

an image pickup unit including an image pickup element configured to capture, in a unit of pixels, a plurality of colors in ranges of visible and invisible light incoming through an image capturing lens;

a pixel value calculating unit configured to calculate a pixel value of each pixel regarding at least one of the colors captured by the image pickup unit;

a contrast value calculating unit configured to calculate a contrast value for each of the at least one color on the basis of the pixel values calculated by the pixel value calculating unit;

a correction value calculating unit configured to calculate a focus correction value for a distance from a current position of the image capturing lens to a focus position of the image capturing lens on the basis of a temporal change in the contrast values of the at least one color calculated by the contrast value calculating unit; and

an image capturing lens driving unit configured to drive the image capturing lens on the basis of the focus correction value calculated by the focus correction value calculating unit.