JP6704718B2 - Imaging device, control method thereof, and control program - Google Patents

Description

The present invention relates to an image pickup apparatus, a control method therefor, and a control program, and particularly to an image pickup apparatus that detects a change in the amount of light from a subject.

Generally, if there is a change (flicker) in the amount of outside light in a predetermined cycle during shooting, so-called uneven exposure may occur. For example, when a CMOS image sensor is used as an image sensor and an image is captured while shifting the storage period for each line of the image sensor, the state of the amount of external light that overlaps the storage period differs for each line. Therefore, a line having a large integrated value of the amount of external light in the accumulation period is bright, a line having a small integrated value of the amount of external light in the accumulation period is dark, and the obtained image is an image with uneven exposure.

If the length of the accumulation period (accumulation time) of each line is equal to or longer than the cycle of the light amount change, the state in which the light amount is maximum and the state in which the light amount is minimum are included in one accumulation period. The uneven exposure is not noticeable. On the other hand, if the accumulation time of each line is shorter than the cycle of light intensity change, a line that overlaps with a state where the light intensity is high and a line that overlaps with a state where the light intensity is low can be separated. The exposure unevenness in the image becomes remarkable.

Therefore, in Japanese Patent Laid-Open No. 2004-242242, an image A obtained by using the accumulation time in which the exposure unevenness becomes remarkable is compared with an image B obtained by using the accumulation time in which the exposure unevenness does not occur, and the image A is generated in the image A. We propose a technique to detect the flicker cycle from the light and dark cycle.

JP, 2015-88917, A

However, as in the technique proposed in Patent Document 1, in order to repeatedly generate light and dark in the image A, from the start of the accumulation of the first line of the image sensor to the end of the accumulation of the last line. The length needs to be about two cycles of the light amount change of the light source.

Therefore, if the image acquisition cycle (frame rate) is faster than a predetermined cycle, bright and dark images do not repeatedly occur in the image, and it becomes difficult to detect the flicker cycle with the technique proposed in Patent Document 1.

Therefore, an object of the present invention is to provide an image pickup apparatus, a control method thereof, and a control program, which are capable of detecting a change in the amount of light from a subject even when the image acquisition cycle is faster than a predetermined cycle. It is in.

To achieve the above object, an imaging apparatus according to the present invention, together with obtaining a first image captured by the first timing determined to be Utsushitai advance, a second timing different from said first timing an image obtaining means for obtaining a second image by imaging the object Utsushitai in, when detecting the presence of flicker in response to the first image and the second image, the first image and the second If the frame rate at the time of obtaining the image of exceeds the preset frame rate, the result obtained by the addition processing of the first image, the second image, and the first image and the second image is obtained. A detection unit that detects the period of the flicker based on the acquired third image.

Control method according to the present invention, together with obtaining a first image captured by the first timing determined to be Utsushitai advance, to be Utsushitai by capturing at a second timing different from said first timing An image acquisition step of obtaining a second image and a frame rate for obtaining the first image and the second image when detecting the presence of flicker according to the first image and the second image Is greater than a preset frame rate, based on the first image, the second image, and a third image obtained as a result of addition processing of the first image and the second image. And a detection step of detecting the period of the flicker.

Program according to the present invention is a control program used in the image pickup apparatus, to a computer in which the imaging device comprises, along with obtaining a first image captured by the first timing determined to be Utsushitai advance, the an image obtaining step of obtaining a second image by imaging the object Utsushitai at a second timing different from the first timing, when detecting the presence of flicker in response to the first image and the second image If the frame rate at the time of obtaining the first image and the second image exceeds a preset frame rate, the first image, the second image, and the first image and the first image. A detection step of detecting the period of the flicker based on a third image obtained as a result of the addition processing of the second image and the second image.

According to the present invention, it is possible to detect a change in the amount of light from a subject even when the image acquisition cycle is faster than a predetermined cycle.

It is a figure which shows the structure of the digital single lens reflex camera which is an example of the imaging device by embodiment of this invention. 6 is a flowchart for explaining a flicker detection process performed by the camera shown in FIG. 1. FIG. 3 is a diagram showing an example of a flicker waveform, shutter driving, and an image when the camera shown in FIG. 1 does not store and read at a high frame rate. 3 is a flowchart for explaining a normal flicker detection process shown in FIG. 2. FIG. 6 is a diagram showing an example of another image generated using two images affected by flicker in the normal flicker detection process shown in FIG. 4. It is a figure which shows an example of calculation of the time difference of the peak timing shown in FIG. FIG. 3 is a diagram showing an example of a flicker waveform, shutter drive, and an image when accumulation and reading are performed at a high frame rate in the camera shown in FIG. 1. 3 is a flowchart for explaining a high frame rate flicker detection process shown in FIG. 2. FIG. 9 is a diagram showing an example of another image generated using two images affected by flicker in the high frame rate flicker detection process shown in FIG. 8. It is a figure which shows an example of calculation of the time difference of the peak timing shown in FIG. 6A and 6B are diagrams for explaining a difference in flicker waveform according to accumulation time, where FIG. 9A is a diagram showing a flicker waveform when the accumulation time is long, and FIG. 9B is a diagram when the accumulation time is short. It is a figure which shows a flicker waveform. It is a figure for demonstrating the difference of the waveform which added the flicker waveform obtained by two continuous frames according to accumulation time, (a) is a figure which shows the waveform which canceled the flicker component, (b) shows the flicker component. It is a figure which shows the remaining waveform.

An example of the image pickup apparatus according to the embodiment of the present invention will be described below. In the following description, a digital single-lens reflex camera will be described as an example of the image pickup apparatus.

FIG. 1 is a diagram showing a configuration of a digital single lens reflex camera which is an example of an image pickup apparatus according to an embodiment of the present invention.

The illustrated digital single-lens reflex camera (hereinafter simply referred to as a camera) includes a camera body (imaging device body) 101 and a photographing lens unit (hereinafter simply referred to as a photographing lens) 102. The camera body 101 and the taking lens 102 are mechanically and electrically connected to each other. The taking lens 102 has a focusing lens (focus lens) 103 and a diaphragm 104, and these focus lens 103 and diaphragm 104 are controlled by the camera body 101 via a lens mount contact group 105.

The camera body 101 is provided with a main mirror 106, and the main mirror 106 is a half mirror. A sub mirror 107 is arranged on the back side of the main mirror 106. FIG. 1 shows a state in which the main mirror 106 is not mirrored up. In this state, part of the light that has entered through the taking lens 102 is reflected by the main mirror 106 and is located above the viewfinder. It is sent to the screen 109. On the other hand, the light transmitted without being reflected by the main mirror 106 is reflected by the sub mirror 107 and enters the AF device 108 arranged below.

Since the AF device 108 performs AF by a so-called phase difference detection method, it condenses the light incident through the taking lens 102, and the condensed light is focused on the image forming surface of the focus detection line sensor (not shown). (That is, an optical image) is formed. Then, the AF device 108 detects the defocus amount and the focus direction as the detection result by the phase difference detection. The CPU 116 drives the focus lens 103 along the optical axis according to the detection result to perform focus adjustment. An optical image (subject image) is formed on the finder screen 109, and the optical image is guided to the eyes of the photographer through the pentaprism 111 and the eyepiece lens 110. This allows the photographer to visually recognize the optical image. The optical image formed on the finder screen 109 is guided to the AE device 112 via the pentaprism 111.

The AE device 112 converts an optical image (that is, an optical finder image) into a photometric image by a photometric sensor in order to observe the brightness of the subject. Then, the AE device 112 detects the brightness of the subject based on the photometric image, and performs the exposure calculation and the subject detection.

An image sensor 113 is arranged at the subsequent stage of the main mirror 106. The image sensor 113 is, for example, a CMOS image sensor or a CCD image sensor, and a plurality of pixels having photoelectric conversion elements are arranged in a two-dimensional matrix.

When taking an image, the main mirror 106 and the sub mirror 107 move from the image-taking optical path. Then, the focal plane shutter 114 arranged on the front side of the image sensor 113 is opened to expose the image sensor 113. That is, an optical image is formed on the image sensor 113. The image sensor 113 outputs an electric signal (analog signal) according to the optical image. Then, the analog signal is converted into a digital signal by A/D conversion and sent to the CPU 116.

The CPU 116 performs predetermined image processing on the digital signal to generate image data. Then, the CPU 116 displays an image corresponding to the image data on the display unit such as the display 115.

As described above, the AE device 112 includes the photometric sensor, performs the exposure calculation based on the photometric image, and outputs the exposure calculation result to the CPU 116. The CPU 116 controls the diaphragm 104 of the taking lens 102 based on the exposure calculation result to adjust the amount of light incident through the taking lens 102. The ICPU 117 performs drive control of the AE device 112 and image processing, and performs flicker detection, photometry, tracking of a subject, and the like, as described later.

FIG. 2 is a flowchart for explaining a flicker detection process performed by the camera shown in FIG. The processing according to the illustrated flowchart is performed under the control of the CPU 116.

When the flicker detection process is started, the CPU 116 controls the AE device 112 by the ICPU 117 to store and read an optical image, that is, charges (step S201). Then, the CPU 116 confirms whether or not the accumulation and reading performed in the process of step S201 is the second time (step S202).

When the accumulation and reading are the first times (NO in step S202), CPU 116 returns to the process of step S201 and performs the second accumulation and reading. In the second accumulation and readout, the CPU 116 adjusts the accumulation and readout timing in order to obtain an image that is affected by a phase opposite to that of the flicker that occurs during the first accumulation and readout. For example, in the second accumulation and reading, the time difference from the first accumulation and reading is set to be approximately (N+1/2) times the light amount change cycle (flicker cycle) of the light source. As a result, the effects of flicker in the image obtained by the first accumulation and reading and the image obtained by the second accumulation and reading have a substantially opposite phase relationship.

By adding the two images obtained here, it is possible to obtain an image in which the influence of flicker is reduced. At this stage, the flicker detection process may be performed before and the flicker period may be known, but the flicker period is unknown when the flicker detection process is performed for the first time after the power is turned on. Therefore, when the flicker cycle is unknown, a time period satisfying a relationship of approximately (N+1/2) times the typical flicker cycle of 1/100 seconds and 1/120 seconds, for example, 1/22 seconds, is set for the first time. It is sufficient to set the time difference between the accumulation and readout of the second and the second accumulation and readout. When the flicker period is known, a time that satisfies the relationship of (N+1/2) times the flicker period may be set. Further, in order to obtain an image in which the influence of flicker is reduced from the addition of images of two consecutive frames, it is necessary to consider that the influence of flicker on an image differs depending on the accumulation time.

FIG. 11 is a diagram for explaining the difference in the flicker waveform depending on the accumulation time. Then, FIG. 11A is a diagram showing a flicker waveform when the accumulation time is long, and FIG. 11B is a diagram showing a flicker waveform when the accumulation time is short.

The effect of flicker on an image changes depending on whether the image is stored for a long time as shown in FIG. 11A or the image is stored for a short time as shown in FIG. 11B. The longer the accumulation time is, the more the light amount of the light source is large and the larger the light amount is, which is likely to overlap with the accumulation period, and the difference in brightness between lines becomes unclear. On the other hand, as the accumulation time is shorter, the state of the light amount of the light source that overlaps the accumulation period becomes clearer for each line, and the difference in brightness between lines becomes clearer.

Therefore, even if the accumulation/readout period is set such that the influence of flicker received in two consecutive frames is shifted by a half phase as described above, an image in which the influence of flicker remains may be obtained.

FIG. 12 is a diagram for explaining a difference in waveform obtained by adding flicker waveforms obtained in two consecutive frames according to the accumulation time. Then, FIG. 12A is a diagram showing a waveform in which the flicker component is canceled, and FIG. 12B is a diagram showing a waveform in which the flicker component remains.

For example, when the flicker period is 1/100 second and the accumulation/reading time difference is set to 15 ms and the accumulation time is set to 1/200 seconds, when images obtained in two consecutive frames are added, FIG. It is possible to obtain an image in which the flicker component is canceled as shown in FIG. On the other hand, when the accumulation time is set to 1/4000 seconds, an image in which a flicker component remains is acquired as shown in FIG. Therefore, by setting the accumulation/reading time difference to the above-mentioned time and then setting the accumulation time to approximately 1/2 of the flicker cycle, an image in which the influence of flicker is reduced by adding two consecutive frames is obtained. To be able to

At this stage, the flicker detection process may be performed before and the flicker period may be known. However, when the flicker detection process is performed for the first time after the power is turned on, the flicker period is unknown. Therefore, when the flicker period is unknown, the time that satisfies the relationship of approximately (1/2) times the typical flicker period of 1/100 seconds and 1/120 seconds, that is, 1/200 seconds and 1/240 seconds. The time between seconds (for example, 1/220 seconds) may be set as the accumulation time. When the flicker period is known, both may be set to 1/2 times the accumulation time of the flicker period.

As described above, if the flicker cycle is known, the time difference between accumulation and reading is set to (N+1/2) times the flicker cycle, and both accumulation times are controlled to be 1/2 times the flicker cycle. When the flicker period is unknown, the time difference becomes about (N+1/2) times, or about 1/2 times, both of the typical flicker period of 1/100 seconds and 1/120 seconds. Control so that the accumulation time is reached.

When the accumulation and reading are the second times (YES in step S202), CPU 116 obtains two images affected by the flicker by the twice accumulation and reading. Then, the CPU 116 determines whether the accumulation and the reading are performed at the high frame rate (step S203).

In the process of step S203, the CPU 116 determines whether or not the frame rate is higher than a predetermined frame rate based on the accumulation and reading cycles. For example, if the peak of flicker occurs twice or more in the accumulation and read cycles, the CPU 116 determines that the frame rate is not high. On the other hand, when the peak of flicker is less than 2 times in the accumulation and reading cycles, the CPU 116 determines that the frame rate is high. At this time, the frame rate at which the flicker peak occurs twice in the accumulation and readout cycles is the predetermined frame rate.

If the frame rate is not high (NO in step S203), CPU 116 performs flicker detection processing (referred to as normal flicker detection processing) when accumulation and reading are not high frame rate (step S204). On the other hand, if the frame rate is high (YES in step S203), the CPU 116 performs a flicker detection process in which accumulation and reading are high frame rates (step S205).

After the processing of step S204 or S205, the CPU 116 performs processing other than the flicker detection processing described later (step S206) and ends the flicker detection processing.

Here, the normal flicker detection process shown in FIG. 2 will be described.

FIG. 3 is a diagram showing an example of a flicker waveform, shutter drive, and an image when the camera shown in FIG. 1 does not store and read at a high frame rate.

In FIG. 3, during reading and storage, the shutter is driven so that the flicker peak is two or more times, and images A and B are obtained. Here, the image A is an image acquired in the first accumulation and reading, and the image B is an image acquired in the second accumulation and reading subsequent to the image A. Then, it can be seen that the effects of flicker in the images A and B are in the relationship of substantially opposite phases.

FIG. 4 is a flow chart for explaining the normal flicker detection process shown in FIG. Further, FIG. 5 is a diagram showing an example of another image generated by using two images affected by flicker in the normal flicker detection process shown in FIG.

Referring to FIGS. 4 and 5, when the normal flicker detection process is started, CPU 116 obtains the ratio between image A and image B (step S401). Then, the CPU 116 generates the image C in which only the flicker component is extracted based on the ratio. That is, the CPU 116 obtains the image C by dividing the image A by the image B. Then, CPU116 detects the peak timing according to the extracted flicker component (step S402). The method of detecting the peak timing of flicker is described in, for example, the above-mentioned Patent Document 1, and therefore its explanation is omitted here.

Next, the CPU 116 uses the flicker peak timing to obtain the flicker cycle based on the time difference of the peak timing (step S403). In this way, the CPU 116 detects the presence of flicker according to the image A and the image B.

FIG. 6 is a diagram showing an example of calculation of the time difference between the peak timings shown in FIG. In FIG. 6, the horizontal axis represents the vertical synchronizing signal (VD) and the vertical axis represents the flicker level.

In the process of step S403, the time difference between peak timings is obtained according to the peak timing of flicker obtained based on the image C. Then, the CPU 116 calculates the flicker cycle based on the time difference.

Subsequently, the CPU 116 performs addition processing on the image A and the image B to obtain the image D shown in FIG. 5 (step S404). Then, the CPU 116 ends the normal flicker detection process. Since the effects of flicker have a substantially opposite phase relationship in images A and B, as a result of the addition process, the effects of flicker are reduced in image D shown in FIG. Then, this image D is used in the process of step S206 shown in FIG.

Next, the flicker detection process for high frame rate shown in FIG. 2 will be described.

FIG. 7 is a diagram showing an example of a flicker waveform, shutter drive, and an image when accumulation and reading are performed at a high frame rate in the camera shown in FIG.

In FIG. 7, during reading and storage, the shutter is driven so that the flicker peak is less than twice, and images A1 and B1 are obtained. Here, the image A1 is an image acquired in the first accumulation and reading, and the image B1 is an image acquired in the second accumulation and reading subsequent to the image A1. Then, it can be seen that the effects of flicker in the images A1 and B1 are in the relationship of substantially opposite phases.

FIG. 8 is a flowchart for explaining the flicker detection process for the high frame rate shown in FIG. FIG. 9 is a diagram showing an example of another image generated using two images affected by flicker in the high frame rate flicker detection process shown in FIG.

Referring to FIGS. 8 and 9, when flicker detection processing for high frame rate is started, CPU 116 performs addition processing on image A1 and image B1 to obtain image D1 shown in FIG. 9 (step S801). Since the image A1 and the image B1 have the flicker influences in a substantially opposite phase relationship, as a result of the addition process, the flicker influence is reduced in the image D1 shown in FIG. Then, the image D1 is used in the process of step S206 shown in FIG.

Subsequently, the CPU 116 obtains the ratio between the image A1 and the image D1 obtained as a result of the addition processing (step S802). Then, the CPU 116 generates the image C1 in which only the flicker component is extracted based on the ratio. That is, the CPU 116 divides the image A1 by the image D1 to obtain the image C1.

Further, the CPU 116 obtains the ratio between the image B1 and the image D1 (step S803). Then, the CPU 116 generates the image C2 in which only the flicker component is extracted based on the ratio. That is, the CPU 116 divides the image B1 by the image D1 to obtain the image C2. These images C1 and C2 will show the flicker component obtained by successive accumulation and readout.

Next, the CPU 116 detects the peak timing of the flicker component in each of the images C1 and C2 (step S804). Then, the CPU 116 obtains the flicker cycle based on the time difference between the peak timings of the flicker of the images C1 and C2 (step S805). Then, the CPU 116 ends the high frame flicker detection process.

FIG. 10 is a diagram showing an example of calculation of the time difference between the peak timings shown in FIG. In FIG. 8, the horizontal axis represents the vertical synchronizing signal (VD) and the vertical axis represents the flicker level for each image.

In the process of step S805, since the flicker peak is less than 2 times in the accumulation and reading cycles, the CPU 116 causes the flicker peak timing obtained based on the image C1 and the flicker peak timing obtained based on the image C2. The time difference between the peak timings is calculated according to Then, the CPU 116 calculates the flicker cycle based on the time difference.

As described above, the influence of flicker is reduced in the image D or the image D1 obtained in the process of step S204 or S205, and the CPU 116 performs a predetermined image process using the image D or the image D1. For example, an image displayed on the display 115 (for example, a live view image) is obtained. By doing so, it is not necessary to separately obtain an image used for processing other than flicker detection, and it is not necessary to perform accumulation and reading in consideration of flicker, and the processing time can be shortened.

As the processing other than the flicker detection, in addition to the display processing for displaying the live view image, for example, photometric processing for measuring the light of the subject, colorimetric processing for measuring the color of the subject, tracking processing for tracking the subject, Then, there is an AF process for focusing on the subject.

After performing the process of step S206, the process returns to the process of step S201, and the accumulation and the reading are performed again. At this time, when it is determined that flicker has not occurred by the processing of step S204 or S205, the CPU 116 reduces the execution frequency of the flicker detection processing thereafter (that is, lengthens the flicker detection execution cycle (that is, the detection cycle)). To).

As described above, according to the embodiment of the present invention, even if shooting is performed at a high frame rate under a flicker light source, the flicker detection process can be performed according to the frame rate. Then, if the image obtained by the flicker detection process is used in a process other than the flicker detection process, it is not necessary to obtain an image to perform a process other than the flicker detection process after the flicker detection process, and the image processing time can be shortened. it can.

That is, according to the embodiment of the present invention, flicker detection is performed even when shooting is performed at a high frame rate, and an image used in processing other than flicker detection is generated based on a plurality of images obtained during flicker detection. To do. This makes it possible to reduce image acquisition and processing time.

In the above-described embodiment, the images used in the processes other than the flicker detection and the flicker detection are obtained by using the two images obtained by the two times of the accumulation and the reading. Alternatively, flicker detection may be performed. Further, in the middle of the flicker detection, the image D1 obtained in the process of the flicker detection processing may be used to perform processing other than the flicker detection.

Further, in the above-described embodiment, the flicker cycle is obtained according to the flicker peak timing, but the flicker cycle may be obtained according to the time difference obtained by the flicker bottom timing. Further, although the flicker component is extracted according to the ratio between the images, the flicker component may be extracted according to the difference between the images.

Further, in the above-described embodiment, the flicker detection is performed using the image obtained from the photometric sensor, but the flicker detection may be performed using the image obtained from the image sensor 113. As is clear from the above description, in the example shown in FIG. 1, the CPU 116, the ICPU 117, and the AE device 112 function as an image acquisition unit. Further, the CPU 116 functions as a detection unit and a processing unit.

Although the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments, and various embodiments within the scope not departing from the gist of the present invention are also included in the present invention. ..

For example, the functions of the above-described embodiments may be used as a control method, and the imaging apparatus may be caused to execute this control method. Further, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the imaging device. The control program is recorded in, for example, a computer-readable recording medium.

[Other Embodiments]
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by the processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

102 Shooting Lens 103 Focusing Lens 104 Aperture 106 Main Mirror 108 AF Device 109 Viewfinder Screen 112 AE Device 113 Image Sensor 115 Display 116 CPU

Claims (12)

Together to obtain a first image captured by the first timing determined to be Utsushitai advance, an image to obtain a second image by imaging the object Utsushitai at a second timing different from said first timing Acquisition means,
When detecting the presence of flicker according to the first image and the second image, when the frame rate for obtaining the first image and the second image exceeds a preset frame rate, A detection unit that detects the period of the flicker based on the first image, the second image, and a third image obtained as a result of the addition processing of the first image and the second image. ,
An image pickup apparatus comprising: Said image acquisition means is to give the accumulation and reading said by controlling the timing of the first image and the second image of the image in the imaging device for outputting an image corresponding to the image of the Utsushitai, wherein The image pickup apparatus according to claim 1, wherein the first timing and the second timing have a substantially opposite phase relationship. When the peak of the flicker is less than two times in the accumulation and readout cycles of the image acquisition unit, the detection unit sets the frame rate for obtaining the first image and the second image to the preset value. The image pickup apparatus according to claim 2, wherein the image pickup apparatus determines that the specified frame rate is exceeded. The detecting means may detect the flicker cycle based on the first image and the second image if the peak of the flicker is two or more times in the accumulation and readout cycles of the image acquisition means. The imaging device according to claim 2 or 3, wherein. The image pickup apparatus according to claim 1, wherein the detection unit lengthens a detection period for detecting flicker when flicker is not detected. The image pickup apparatus according to any one of claims 1 to 5, further comprising a processing unit that performs another process using the third image. The other processing is the photometric process for photometry of the Utsushitai, colorimetric process for measuring the color of the Utsushitai, tracking process for tracking the Utsushitai, AF processing for focusing with respect to the Utsushitai, and The image pickup apparatus according to claim 6, wherein the image pickup apparatus is at least one of display processing for performing live view image display. The image capturing apparatus according to any one of claims 1 to 7, wherein the image acquisition unit equalizes the accumulation times when the first image and the second image are obtained. When the image acquisition unit detects the flicker period by the detection unit, the accumulation time for obtaining the first image and the second image is set to ½ times the flicker period. The imaging device according to claim 8, wherein When the image acquisition unit does not detect the flicker cycle by the detection unit, the accumulation time when obtaining the first image and the second image is 1/200 seconds and 1/240 seconds. The image pickup apparatus according to claim 8 or 9, wherein the image pickup apparatus has a time interval between them. Together to obtain a first image captured by the first timing determined to be Utsushitai advance, an image to obtain a second image by imaging the object Utsushitai at a second timing different from said first timing Acquisition step,
When detecting the presence of flicker according to the first image and the second image, if the frame rate for obtaining the first image and the second image exceeds a preset frame rate, A detection step of detecting the period of the flicker based on the first image, the second image, and a third image obtained as a result of the addition processing of the first image and the second image; ,
A control method comprising: A control program used in an imaging device,
In the computer included in the imaging device ,
Together to obtain a first image captured by the first timing determined to be Utsushitai advance, an image to obtain a second image by imaging the object Utsushitai at a second timing different from said first timing Acquisition step,
When detecting the presence of flicker according to the first image and the second image, when the frame rate for obtaining the first image and the second image exceeds a preset frame rate, A detection step of detecting the period of the flicker based on the first image, the second image, and a third image obtained as a result of the addition processing of the first image and the second image; ,
A control program for executing the following.