IMAGE CAPTURING APPARATUS

• US 20140240550A1
• Filed: 02/19/2014
• Published: 08/28/2014
• Est. Priority Date: 02/27/2013
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Taniguchi, Hidenori, Hirose, Minoru
• Granted Patent: US 9,503,616 B2
• Time in Patent Office: Days
• US Class Current: 348/239
• CPC Class Codes: H04N 23/672 based on the phase difference signals
• 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 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/704 Pixels specially adapted for focusing, e.g. phase difference pixel sets

Abstract

An image capturing apparatus comprises an image sensor constructed by replacing some of a plurality of image forming pixels of the image sensor with focus detecting pixels, a comparison unit configured to compare outputs of the image forming pixels as a plurality of correction targets adjacent to the focus detecting pixel with outputs of a plurality of reference image forming pixels of the same color as the plurality of image forming pixels arranged in the vicinity of the plurality of image forming pixels adjacent to the focus detecting pixel, and a correction unit configured to execute correction processing of the outputs of the image forming pixels as the plurality of correction targets in accordance with a comparison result of the comparison unit.

Claims

1. An image capturing apparatus comprising:

an image sensor constructed by replacing some of a plurality of image forming pixels of said image sensor with focus detecting pixels;

a comparison unit configured to compare outputs of the image forming pixels as a plurality of correction targets adjacent to the focus detecting pixel with outputs of a plurality of reference image forming pixels of the same color as the plurality of image forming pixels arranged in the vicinity of the plurality of image forming pixels adjacent to the focus detecting pixel; and

a correction unit configured to execute correction processing of the outputs of the image forming pixels as the plurality of correction targets in accordance with a comparison result of said comparison unit.

2. The apparatus according to claim 1, wherein said correction unit calculates an average value of the outputs of the plurality of reference image forming pixels, and executes the correction processing when the calculated average value is within a predetermined range.

3. The apparatus according to claim 1, wherein said correction unit calculates a correction amount of the outputs of the image forming pixels as the plurality of correction targets based on a pixel having a highest output level out of the image forming pixels as the plurality of correction targets.

4. The apparatus according to claim 1, wherein said correction unit calculates random noise of the reference image forming pixels based on an average value of the outputs of the plurality of reference image forming pixels.

5. The apparatus according to claim 1, wherein said correction unit calculates a difference between the outputs of the image forming pixels as the plurality of correction targets and an average value of the outputs of the plurality of reference image forming pixels, and executes the correction processing when the calculated difference is not less than a predetermined value.

6. The apparatus according to claim 5, wherein said correction unit calculates a correction amount of the outputs of the image forming pixels as the plurality of correction targets by multiplying the difference by a predetermined coefficient.

7. The apparatus according to claim 1, wherein said correction unit calculates a contrast value based on a difference between a maximum value and a minimum value of the outputs of the plurality of reference image forming pixels, and compares the contrast value with a predetermined value, thereby judging whether to execute the correction processing.

8. The apparatus according to claim 7, wherein said correction unit shifts the predetermined value to be compared with the contrast value in accordance with the contrast value.

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

a photometry unit configured to detect a luminance value of an object; and

a correction switching unit configured to switch an operation of said correction unit in accordance with an output of said photometry unit.

10. The apparatus according to claim 9, wherein said correction switching unit enables the operation of said correction unit when the luminance value of the object detected by said photometry unit is included in a predetermined luminance range.

11. The apparatus according to claim 9, wherein said photometry unit outputs the luminance value of the object in each of a plurality of divided regions, and

said correction switching unit enables the operation of said correction unit when a maximum luminance value in the plurality of divided regions is not less than a predetermined value.

12. The apparatus according to claim 9, further comprising an exposure control unit configured to set an exposure condition in a shooting operation,

wherein said correction switching unit enables the operation of said correction unit when a difference between the luminance value of the object detected by said photometry unit and a shooting exposure control value set by said exposure control unit is not less than a predetermined value.

13. The apparatus according to claim 12, wherein said correction switching unit selects the predetermined value in accordance with the luminance value of the object detected by said photometry unit.

14. The apparatus according to claim 9, further comprising a saturated pixel count unit configured to count the number of pixels having not less than a predetermined luminance value,

wherein said correction switching unit enables the operation of said correction unit when the number of pixels counted by said saturated pixel count unit is not less than a predetermined number of pixels.