IMAGE PICKUP APPARATUS THAT PERFORMS FLICKER DETECTION, CONTROL METHOD FOR IMAGE PICKUP APPARATUS, AND STORAGE MEDIUM

• US 20200137291A1
• Filed: 10/29/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ota, Kohei
• Granted Patent: US 11,102,423 B2
• Time in Patent Office: Days
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• 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 includes an image pickup device that picks up a subject by driving by a rolling shutter method, a memory that stores a set of instructions and at least one processor that executes the instructions to divide, when driving the image pickup device at a second frame rate lower than a first frame rate, a plurality pieces of image data successively acquired by the image pickup device at the second frame rate into predetermined areas to acquire data of divided areas, and perform flicker detection using a predetermined number of pieces of the data of the divided areas successive for a plurality of frames.

Claims

1. An image pickup apparatus comprising:

an image pickup device that picks up a subject by driving by a rolling shutter method;

a memory that stores a set of instructions; and

at least one processor that executes the instructions to divide, when driving the image pickup device at a second frame rate lower than a first frame rate, a plurality pieces of image data successively acquired by the image pickup device at the second frame rate into predetermined areas to acquire data of divided areas, and perform flicker detection using a predetermined number of pieces of the data of the divided areas successive for a plurality of frames.

2. The image pickup apparatus of claim 1, wherein

the processor executes the instructions to perform, when luminance of the image data is higher than a threshold value, flicker detection based on a plurality of pieces of image data obtained by driving the image pickup device at the first frame rate, and perform, when the luminance is equal to or lower than the threshold value, flicker detection based on the data of the divided areas obtained by driving the image pickup device at the second frame rate.

3. The image pickup apparatus of claim 2, wherein

the processor executes the instructions to perform, when driving the image pickup device at the first frame rate, the flicker detection based on change with time of a value obtained by integrating the luminance of the plurality of pieces of image data, and perform, when driving the image pickup device at the second frame rate, the flicker detection based on change with time of a value obtained by integrating the luminance of the data of the divided areas.

4. The image pickup apparatus of claim 1, wherein

the second frame rate is a frame rate obtained by dividing the first frame rate by an integer value of two or more, and wherein

the processor executes the instructions to divide the image data by the integer value.

5. The image pickup apparatus of claim 1, wherein

the processor executes the instructions to perform, when driving the image pickup device at the second frame rate, flicker detection based on predetermined image data whose degree of flicker influence is smaller than a predetermined amount and each of the data of the divided areas.

6. The image pickup apparatus of claim 5, wherein

the processor executes the instructions to perform the flicker detection by obtaining a difference or a ratio between the predetermined image data and each of the data of the divided areas.

7. The image pickup apparatus of claim 1, wherein

the processor executes the instructions to perform, when a blanking period occurs at a time of performing the successive shooting, interpolation using the data of the divided areas before and after the blanking period.

8. The image pickup apparatus of claim 1, wherein the processor executes the instructions to perform, when driving the image pickup device at the first frame rate, flicker detection based on change with time of an integrated value of luminance of data of a partial area of a plurality of pieces of image data successively acquired by the image pickup device.

9. The image pickup apparatus of claim 1, wherein

the processor executes the instructions to set, when live view display is performed, a frame rate lower than a frame rate for performing live view display, and perform flicker detection based on change in luminance of successive images acquired in accordance with the set frame rate.

10. The image pickup apparatus of claim 1, wherein

the processor executes the instructions to calculate a flicker waveform based on change with time of a value obtained by integrating luminance for each data of the divided areas, and synthesize a flicker waveform of each calculated data of the divided areas.

11. The image pickup apparatus according to claim 1, wherein

a number of divisions of the image data for obtaining the data of the divided areas is set in accordance with a ratio of the second frame rate to the first frame rate.

12. A control method for an image pickup apparatus including an image pickup device that picks up a subject by driving by a rolling shutter method, the control method comprising:

dividing, when driving the image pickup device at a second frame rate lower than a first frame rate, a plurality pieces of image data successively acquired by the image pickup device at the second frame rate into predetermined areas to acquire data of divided areas, and performing flicker detection using a predetermined number of pieces of the data of the divided areas successive for a plurality of frames.

13. A non-transitory computer-readable storage medium storing a computer-executable program that executes a control method for an image pickup apparatus including an image pickup device that picks up a subject by driving by a rolling shutter method, the control method comprising:

dividing, when driving the image pickup device at a second frame rate lower than a first frame rate, a plurality pieces of image data successively acquired by the image pickup device at the second frame rate into predetermined areas to acquire data of divided areas, and performing flicker detection using a predetermined number of pieces of the data of the divided areas successive for a plurality of frames.