IMAGE PICKUP APPARATUS THAT REDUCES TIME REQUIRED FOR LIGHT CONTROL PROCESSING AND METHOD OF CONTROLLING SAME

• US 20190313003A1
• Filed: 03/29/2019
• Published: 10/10/2019
• Est. Priority Date: 04/04/2018
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shintani, Takuya
• Granted Patent: US 11,115,603 B2
• Time in Patent Office: Days
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 7/097 for control of both exposure time and aperture
• CPC Class Codes: G03B 7/28 Circuitry to measure or to take account of the object contrast
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 40/166 using acquisition arrangements
• CPC Class Codes: H04B 10/502 LED transmitters
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination

Abstract

An image pickup apparatus that performs, when photographing an object, photographing by causing a light emission device to emit light to the object. A photometry sensor selectively obtains a first image having a first resolution and a second image having a second resolution lower than the first resolution, as a photometric image, and performs photometry using the obtained photometric image to thereby obtain a result of photometry. When performing light control processing for determining a main light emission amount for causing the light emission device to perform main light emission for photographing the object, the light control is switched between first control for performing light control processing based on the first image and second control for performing light control processing based on the second image, according to a result of determination of whether or not a predetermined condition is satisfied.

Claims

1. An image pickup apparatus that photographs an object by causing a light emission device to emit light toward the object, comprising at least one processor that functions, according to at least one program stored in a memory, as units comprising:

a photometry unit configured to selectively obtain a first image having a first resolution and a second image having a second resolution lower than the first resolution, as a photometric image, and performs photometry using the obtained photometric image to thereby obtain a result of photometry;

a determination unit configured to determine whether or not a predetermined condition is satisfied; and

a control unit configured to control, when performing light control processing for determining a main light emission amount for causing the light emission device to perform main light emission for photographing the object, the photometry unit to switch between first control in which the light control processing is performed based on the first image and second control in which the light control processing is performed based on the second image, according to a result of determination performed by the determination unit.

2. The image pickup apparatus according to claim 1, wherein the photometry unit includes an image pickup device having a plurality of pixels,

wherein the first image is an image obtained by reading all pixels of the image pickup device, and

wherein the second image is an image read by performing addition processing on the pixels of the image pickup device.

3. The image pickup apparatus according to claim 1, wherein in a case where a predetermined area of the object is detected from the photometric image, the determination unit determines that the predetermined condition is satisfied.

4. The image pickup apparatus according to claim 1, wherein in a case where a luminance of the photometric image is not lower than a predetermined luminance, the determination unit determines that the predetermined condition is satisfied.

5. The image pickup apparatus according to claim 1 wherein in a case where flicker is detected from the photometric image, the determination unit determines that the predetermined condition is satisfied.

6. The image pickup apparatus according to claim 1 further comprising a measurement unit configured to measure a distance between the image pickup apparatus and the object to obtain distance information, and

wherein in a case where a distance indicated by the distance information obtained by the measurement unit is within a predetermined range, the determination unit determines that the predetermined condition is satisfied.

7. The image pickup apparatus according to claim 1, wherein in a case where it is determined by the determination unit that the predetermined condition is satisfied, the control unit performs the second control.

8. The image pickup apparatus according to claim 7, wherein in the second control, the control unit controls the photometry unit before preliminary light emission by the light emission device to perform processing for obtaining the second image before the preliminary light emission and obtaining a first photometry result by performing photometry using the second image obtained before the preliminary light emission, controls the photometry unit during the preliminary light emission by the light emission device to perform processing for obtaining the second image during the preliminary light emission and obtaining a second photometry result by performing photometry using the second image obtained during the preliminary light emission, and determines the main light emission amount for causing the light emission device to perform the main light emission based on the first photometry result and the second photometry result.

9. The image pickup apparatus according to claim 8, wherein the control unit performs the processing for obtaining the first photometry result and the processing for obtaining the second image during the preliminary light emission in parallel.

10. The image pickup apparatus according to claim 1, wherein in a case where it is determined by the determination unit that the predetermined condition is not satisfied, the control unit performs the first control.

11. The image pickup apparatus according to claim 10, wherein in the first control, the control unit controls the photometry unit during preliminary light emission by the light emission device to perform processing for obtaining the first image during the preliminary light emission and obtaining a third photometry result by performing photometry using the first image obtained during the preliminary light emission, controls the photometry unit after the preliminary light emission by the light emission device to perform processing for obtaining the first image after the preliminary light emission and obtaining a fourth photometry result by performing photometry using the first image obtained after the preliminary light emission, and perform processing for detecting a predetermined area using the first image obtained during the preliminary light emission, and determines the main light emission amount for causing the light emission device to perform the main light emission based on the third photometry result and the fourth photometry result.

12. The image pickup apparatus according to claim 11, wherein the control unit performs the processing for obtaining the third photometry result, the processing for detecting the predetermined area, and the processing for obtaining the first image after the preliminary light emission in parallel.

13. The image pickup apparatus according to claim 3, wherein after a first-taken image has been photographed, when a second-taken image is photographed after the first-taken image, the control unit controls the determination unit to determine whether or not the predetermined condition is satisfied in the first-taken image.

14. The image pickup apparatus according to claim 13, wherein the control unit performs the second control in the light control processing performed for photographing the second-taken image.

15. The image pickup apparatus according to claim 3, wherein in a case where it is determined by the determination unit that the predetermined condition is satisfied, the control unit controls the photometry unit to perform processing for obtaining the first image during preliminary light emission by the light emission device and obtaining a first photometry result by performing photometry using the first image obtained during the preliminary light emission, and further perform processing for obtaining the second image after the preliminary light emission by the light emission device and obtaining a second photometry result by performing photometry using the second image obtained after the preliminary light emission, and determines the main light emission amount for causing the light emission device to perform the main light emission based on the first photometry result and the second photometry result.

16. The image pickup apparatus according to claim 15, wherein in a case where it is determined by the determination unit that the predetermined condition is not satisfied, the control unit detects the predetermined area using the first image obtained during the preliminary light emission.

17. An image pickup apparatus that is capable of performing light emission photographing in which a light emission device is caused to emit light, comprising at least one processor that functions, according to at least one program stored in a memory, as units comprising:

a face detection unit configured to perform face detection processing on an image obtained using an image sensor, for detecting a face area from an object;

a calculation unit configured to calculate a main light emission amount of the light emission device based on information on the face area detected by the face detection processing, non-light emission image obtained using the image sensor without causing the light emission device to emit light, a preliminary light emission image obtained using the image sensor by causing the light emission device to perform preliminary light emission; and

a control unit configured to perform control, in a case where the face detection processing is performed on the preliminary light emission image, such that the non-light emission image is obtained after the preliminary light emission image is obtained.

18. The image pickup apparatus according to claim 17, wherein in a case where the face detection processing is not performed on the preliminary light emission image, the control unit performs control such that the preliminary light emission image is obtained after the non-light emission image is obtained.

19. The image pickup apparatus according to claim 17, wherein resolution of the non-light emission image is made different between a case where the face detection processing is not performed on the preliminary light emission image and a case where the face detection processing is performed on the preliminary light emission image.

20. The image pickup apparatus according to claim 17, wherein the face detection processing on the preliminary light emission image is performed in parallel with processing for obtaining the non-light emission image.

21. The image pickup apparatus according to claim 17, wherein in a case where no face area is detected before the preliminary light emission, the face detection processing is performed on the preliminary light emission image.

22. The image pickup apparatus according to claim 17, wherein in a case where a result of the photometry obtained before the preliminary light emission is lower than a predetermined value, the face detection processing is performed on the preliminary light emission image.

23. The image pickup apparatus according to claim 17, wherein in a case where an object distance is within a predetermined range, the face detection processing is performed on the preliminary light emission image.

24. A method of controlling an image pickup apparatus that photographs an object by causing a light emission device to emit light toward the object, comprising:

selectively obtaining a first image having a first resolution and a second image having a second resolution lower than the first resolution, as a photometric image, and performing photometry using the obtained photometric image to thereby obtain a result of photometry;

determining whether or not a predetermined condition is satisfied; and

switching, when performing light control processing for determining a main light emission amount for causing the light emission device to perform main light emission for photographing the object, between first control in which the light control processing is performed based on the first image and second control in which the light control processing is performed based on the second image, according to a result of determination performed by said determining

25. A method of controlling an image pickup apparatus that is capable of performing light emission photographing in which a light emission device is caused to emit light, comprising:

performing face detection processing on an image obtained using an image sensor, for detecting a face area from an object;

calculating a main light emission amount of the light emission device based on information on the face area detected by the face detection processing, non-light emission image obtained using the image sensor without causing the light emission device to emit light, a preliminary light emission image obtained using the image sensor by causing the light emission device to perform preliminary light emission; and

controlling, in a case where the face detection processing is performed on the preliminary light emission image, such that the non-light emission image is obtained after the preliminary light emission image is obtained.