Image capturing apparatus

• US 9,503,616 B2
• Filed: 02/19/2014
• Issued: 11/22/2016
• 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
• Primary Examiner(s): Moe, Aung S
• Assistant Examiner(s): Cowan, Euel
• Application Number:
  US14/183,699
• Publication Number:
  US 20140240550A1
• Time in Patent Office: 1,007 Days
• Field of Search: None
• US Class Current: 1/1
• 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 configured to include a plurality of first pixels and a second pixel having a photoelectric conversion area which is more greatly shielded from light than a photoelectric conversion area of the first pixel;

a comparison unit configured to compare outputs of the first pixels as a plurality of correction target pixels with outputs of the first pixels as a plurality of reference pixels which are arranged at a position more distant from the second pixel than the correction target pixels; and

a correction unit configured to execute correction processing of the correction target pixels in accordance with a comparison result of the comparison unit,

wherein the correction unit executes the correction processing when the outputs of the plurality of reference pixels are within a predetermined range, and does not execute the correction processing when the outputs of the plurality of reference pixel is beyond the predetermined range.

2. The apparatus according to claim 1, wherein the correction unit calculates a correction amount of the outputs of the first pixels as the plurality of correction target pixels based on a pixel having a highest output level out of the first pixels as the plurality of correction target pixels.

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

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

5. The apparatus according to claim 4, wherein the correction unit calculates a correction amount of the outputs of the first pixels as the plurality of correction target pixels by multiplying the difference by a predetermined coefficient.

6. The apparatus according to claim 1, wherein the 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 pixels, and compares the contrast value with a predetermined value, thereby judging whether to execute the correction processing.

7. The apparatus according to claim 6, wherein the correction unit shifts the predetermined value to be compared with the contrast value in accordance with the contrast value.

8. 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 the correction unit in accordance with an output of the photometry unit.

9. The apparatus according to claim 8, wherein the correction switching unit enables the operation of the correction unit when the luminance value of the object detected by the photometry unit is included in a predetermined luminance range.

10. The apparatus according to claim 8, wherein the photometry unit outputs the luminance value of the object in each of a plurality of divided regions, and

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

11. The apparatus according to claim 8, further comprising an exposure control unit configured to set an exposure condition in a shooting operation,

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

12. The apparatus according to claim 11, wherein the correction switching unit selects the predetermined value in accordance with the luminance value of the object detected by the photometry unit.

13. The apparatus according to claim 8, further comprising a saturated pixel count unit configured to count the number of pixels having not less than a predetermined luminance value,

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

14. The apparatus according to claim 1, wherein the image sensor has a plurality of second pixels.

15. The apparatus according to claim 14, wherein the second pixels are arranged more discretely than the first pixels.

16. The apparatus according to claim 1, wherein each of the second pixels has an opening which makes light enter to the photoelectric conversion area of the second pixel.

17. The apparatus according to claim 16, wherein a center of the opening is shifted from a center of the second pixel.

18. The apparatus according to claim 1, wherein the correction unit executes the correction processing when the calculated average value of the outputs of the plurality of reference pixels is within a predetermined range, and does not executes the correction processing when the calculated average value is beyond the predetermined range.

19. An image capturing apparatus comprising:

an image sensor configured to include a plurality of first pixels and a second pixel having a photoelectric conversion area which is more greatly shielded from light than a photoelectric conversion area of the first pixel;

a comparison unit configured to compare outputs of the first pixels as a plurality of correction target pixels with outputs of the first pixels as a plurality of reference pixels which are arranged at a position more distant from the second pixel than the correction target pixels; and

a correction unit configured to execute correction processing of the correction target pixels in accordance with a comparison result of said comparison unit,

wherein the correction unit executes the correction processing when a difference, which is a difference between the outputs of the first pixels as the plurality of correction target pixels and the outputs of the plurality of reference pixels, is not less than a predetermined value, and does not execute the correction processing when the difference is less than the predetermined value.

20. The apparatus according to claim 19, wherein the correction unit calculates a correction amount of the outputs of the first pixels as the plurality of correction target pixels based on a pixel having a highest output level out of the first pixels as the plurality of correction target pixels.

21. The apparatus according to claim 19, wherein the correction unit calculates random noise of the reference pixels based on an average value of the outputs of the plurality of reference pixels.

22. The apparatus according to claim 19, wherein the correction unit calculates a correction amount of the outputs of the first pixels as the plurality of correction target pixels by multiplying the difference by a predetermined coefficient.

23. The apparatus according to claim 19, wherein the 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 pixels, and compares the contrast value with a predetermined value, thereby judging whether to execute the correction processing.

24. The apparatus according to claim 23, wherein the correction unit shifts the predetermined value to be compared with the contrast value in accordance with the contrast value.

25. The apparatus according to claim 19, 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 the correction unit in accordance with an output of the photometry unit.

26. The apparatus according to claim 25, wherein the correction switching unit enables the operation of the correction unit when the luminance value of the object detected by the photometry unit is included in a predetermined luminance range.

27. The apparatus according to claim 25, wherein the photometry unit outputs the luminance value of the object in each of a plurality of divided regions, and

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

28. The apparatus according to claim 25, further comprising an exposure control unit configured to set an exposure condition in a shooting operation,

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

29. The apparatus according to claim 28, wherein the correction switching unit selects the predetermined value in accordance with the luminance value of the object detected by the photometry unit.

30. The apparatus according to claim 25, further comprising a saturated pixel count unit configured to count the number of pixels having not less than a predetermined luminance value,

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

31. The apparatus according to claim 19, wherein the image sensor has a plurality of second pixels.

32. The apparatus according to claim 31, wherein the second pixels are arranged more discretely than the first pixels.

33. The apparatus according to claim 19, wherein each of the second pixels has an opening which makes light enter to the photoelectric conversion area of the second pixel.

34. The apparatus according to claim 33, wherein a center of the opening is shifted from a center of the second pixel.

35. The apparatus according to claim 19, wherein the correction unit executes the correction processing when a difference, which is a difference between the outputs of the first pixels as the plurality of correction target pixels and an average value of the outputs of the plurality of reference pixels, is not less than a predetermined value, and does not execute the correction processing when the difference is less than the predetermined value.