JP2017103589A - Imaging apparatus, method for controlling the same, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the light quantity change of light from a subject, even when a period for acquiring an image is faster than a predetermined period.SOLUTION: A CPU 116 controls an ICPU 117, so as to image the subject at a first timing by an AE device 112 and obtain a first image and so as to obtain a second image at a second timing different from the first timing. When detecting the presence of a flicker according to the first and second images and when a frame rate when obtaining the first and second images is a high frame rate, the CPU detects the period of the flicker on the basis of the first and second images and a third image obtained by adding the first and second images.SELECTED DRAWING: Figure 2

Description

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

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

  If the length of the accumulation period of each line (accumulation time) is equal to or longer than the period of change in light amount, the maximum amount of light and the minimum amount of light are included in one accumulation period. The exposure unevenness of is inconspicuous. On the other hand, if the accumulation time of each line is shorter than the light amount change cycle, the line that overlaps the state in which the accumulation period has a large amount of light and the line that overlaps the state in which the accumulation period has a small amount of light can be separated. The exposure unevenness in the image becomes remarkable.

  Therefore, in Patent Document 1, the image A acquired using the accumulation time in which the exposure unevenness is remarkable is compared with the image B acquired using the storage time in which the exposure unevenness does not occur, and is generated in the image A. A technique for detecting the flicker period from the light-dark period is proposed.

JP 2015-88917 A

  However, as in the technique proposed in Patent Document 1, in order to repeatedly generate brightness and darkness in the image A, from the start of accumulation of the first line of the image sensor to the end of accumulation of the last line. The length is required for about two periods of the light amount change period of the light source.

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

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

  In order to achieve the above object, the imaging apparatus according to the present invention captures the subject at a predetermined first timing to obtain a first image, and at a second timing different from the first timing. Image acquisition means for capturing the subject to obtain a second image, and when detecting the presence of flicker according to the first image and the second image, the first image and the second image Obtained when the first image, the second image, and the first image and the second image are added together when the frame rate for obtaining the image exceeds a preset frame rate. Detecting means for detecting the flicker period based on a third image.

  The control method according to the present invention captures the subject at a predetermined first timing to obtain a first image, and captures the subject at a second timing different from the first timing. The image acquisition step for obtaining the first image and the frame rate for obtaining the first image and the second image when detecting the presence of flicker in accordance with the first image and the second image are determined in advance. When the set frame rate is exceeded, the first image, the second image, and the third image obtained as a result of the addition processing of the first image and the second image, And a detection step of detecting a flicker cycle.

  A control program according to the present invention is a control program used in an imaging device, and obtains a first image by capturing the subject at a predetermined first timing on a computer included in the imaging device, and An image acquisition step of capturing the subject at a second timing different from the first timing to obtain a second image, and detecting the presence of flicker according to the first image and the second image, When a frame rate for obtaining the first image and the second image exceeds a preset frame rate, the first image, the second image, the first image, and the second image And a detection step of detecting the flicker period based on a third image obtained as a result of the addition processing of the images.

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

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. It is a flowchart for demonstrating the flicker detection process performed with the camera shown in FIG. FIG. 2 is a diagram illustrating an example of a flicker waveform, shutter driving, and an image when accumulation and readout are not performed at a high frame rate in the camera illustrated in FIG. 1. 3 is a flowchart for explaining a normal flicker detection process shown in FIG. 2. FIG. 5 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. FIG. 5 is a diagram illustrating an example of calculation of a time difference between peak timings illustrated in FIG. 4. FIG. 2 is a diagram illustrating an example of a flicker waveform, shutter driving, and an image when accumulation and readout are performed at a high frame rate in the camera illustrated in FIG. 1. 3 is a flowchart for explaining a flicker detection process for a high frame rate shown in FIG. 2. FIG. 9 is a diagram illustrating an example of another image generated using two images affected by flicker in the flicker detection process for high frame rate illustrated in FIG. 8. It is a figure which shows an example of calculation of the time difference of the peak timing shown in FIG. It is a figure for demonstrating the difference of the flicker waveform according to accumulation | storage time, (a) is a figure which shows a flicker waveform when accumulation | storage time is long second, (b) is a case where accumulation | storage time is short second. 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 2 continuous frames according to accumulation time, (a) is a figure which shows the waveform which canceled the flicker component, (b) is a figure which shows the flicker component. It is a figure which shows the waveform which remains.

  Hereinafter, an example of the imaging apparatus according to the embodiment of the present invention will be described. In the following description, a digital single-lens reflex camera will be described as an example of the imaging device.

  FIG. 1 is a diagram illustrating a configuration of a digital single-lens reflex camera that is an example of an imaging 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 photographing lens 102 are mechanically and electrically connected to each other. The photographing lens 102 includes a focusing lens (focus lens) 103 and a diaphragm 104, and the focus lens 103 and the 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, which is a half mirror. A sub mirror 107 is arranged on the back side of the main mirror 106. FIG. 1 shows a state where the main mirror 106 is not mirror-up. In this state, a part of the light incident through the photographing lens 102 is reflected by the main mirror 106 and positioned above the finder. 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 disposed below.

  Since the AF device 108 performs AF by a so-called phase difference detection method, the light incident through the photographing lens 102 is condensed, and the condensed light is focused on the imaging surface of a 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 detection results by phase difference detection. The CPU 116 performs focus adjustment by driving the focus lens 103 along the optical axis according to the detection result. An optical image (subject image) is formed on the finder screen 109, and the optical image is guided to the photographer's eyes through the pentaprism 111 and the eyepiece 110. Thereby, the photographer can 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 viewfinder image) into a photometric image by a photometric sensor in order to observe the brightness of the subject. The AE device 112 detects the brightness of the subject based on the photometric image, and performs exposure calculation and subject detection.

  An image sensor 113 is arranged at the rear stage of the main mirror 106. The imaging element 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 shooting, the main mirror 106 and the sub mirror 107 move from the shooting optical path. Then, the focal plane shutter 114 disposed on the front side of the image sensor 113 is opened, and the image sensor 113 is exposed. That is, an optical image is formed on the image sensor 113. The image sensor 113 outputs an electrical signal (analog signal) corresponding to the optical image. 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 a display unit such as the display 115.

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

  FIG. 2 is a flowchart for explaining the flicker detection process performed by the camera shown in FIG. Note that 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, a charge (step S201). Then, the CPU 116 checks whether or not the accumulation and reading performed in the process of step S201 is the second time (step S202).

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

  By adding the two images obtained here, an image with reduced influence of flicker can be acquired. At this stage, there is a case where the flicker detection process is performed before and the flicker period is 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 cycle is unknown, a time satisfying a substantially (N + 1/2) times relationship with respect to the typical flicker cycle of 1/100 seconds and 1/120 seconds, for example 1/22 seconds, is What is necessary is just to set to the time difference of accumulation | storage and reading of this, and 2nd accumulation | storage and reading. When the flicker cycle is known, a time that satisfies the relationship of (N + 1/2) times the flicker cycle may be set. In addition, in order to obtain an image in which the influence of flicker is reduced by adding two consecutive frames of images, it is necessary to consider that the influence of flicker on the image varies depending on the accumulation time.

  FIG. 11 is a diagram for explaining the difference in the flicker waveform according to the accumulation time. FIG. 11A is a diagram showing a flicker waveform when the accumulation time is a long second, and FIG. 11B is a diagram showing a flicker waveform when the accumulation time is a short second.

  As shown in FIG. 11 (a), the effect of flicker on the image changes depending on whether the image is accumulated in a long time as in FIG. 11 (b) or in the case where the image is accumulated in a short time as shown in FIG. The longer the accumulation time, the easier it is to overlap the accumulation period in both the small and large amounts of light from the light source, and the difference in brightness between lines becomes unclear. On the other hand, the shorter the accumulation time, the clearer the light quantity of the light source that overlaps the accumulation period for each line, and the light / dark difference between the lines becomes clear.

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

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

  For example, when the flicker cycle is 1/100 seconds and the accumulation / readout time difference is set to 15 ms and the accumulation time is set to 1/200 seconds, the images obtained in two consecutive frames are added, as shown in FIG. 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 the flicker component remains is acquired as shown in FIG. Therefore, by setting the time difference between accumulation and readout to the above-mentioned time, and setting the accumulation time to approximately ½ times 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, there is a case where the flicker detection process is performed before and the flicker period is 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 satisfying the relationship of (1/2) times the typical flicker period of 1/100 second and 1/120 second, that is, 1/200 second and 1/240. A 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 an accumulation time that is ½ times the flicker period.

  As described above, if the flicker period is known, the accumulation / reading time difference is controlled to be (N + 1/2) times the flicker period, and both accumulation times are controlled to be 1/2 the flicker period. When the flicker cycle is unknown, the time difference is approximately (N + 1/2) times, and approximately 1/2 times, both of the typical flicker cycles of 1/100 seconds and 1/120 seconds. Control the accumulation time.

  If accumulation and reading are the second time (YES in step S202), CPU 116 acquires two images affected by flicker by the two times of accumulation and reading. Then, the CPU 116 determines whether accumulation and reading are performed at a 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 readout cycle. For example, if there are two or more flicker peaks in the accumulation and readout cycle, the CPU 116 determines that the frame rate is not high. On the other hand, if the flicker peak is less than twice in the accumulation and readout cycle, the CPU 116 determines that the frame rate is high. At this time, the frame rate at which the flicker peak is twice in the accumulation and readout cycle is the predetermined frame rate.

  If the frame rate is not high (NO in step S203), the CPU performs a flicker detection process (referred to as a normal flicker detection process) when the accumulation and reading are not at a high frame rate (step S204). On the other hand, if the frame rate is high (YES in step S203), CPU 116 performs flicker detection processing in which accumulation and reading are at a high frame rate (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 illustrating an example of a flicker waveform, shutter driving, and an image when accumulation and readout are not performed at a high frame rate in the camera illustrated in FIG. 1.

  In FIG. 3, when reading and accumulating, the shutter is driven so that the flicker peak is twice or more, and images A and B are obtained. Here, the image A is an image obtained in the first accumulation and readout, and the image B is an image obtained in the second accumulation and readout following the image A. It can be seen that the effects of flicker in the images A and B have a substantially opposite phase relationship.

  FIG. 4 is a flowchart for explaining the normal flicker detection process shown in FIG. FIG. 5 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 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 an image C in which only the flicker component is extracted based on the ratio. That is, the CPU 116 obtains an image C by dividing the image A by the image B. Subsequently, the CPU 116 detects the peak timing according to the extracted flicker component (step S402). Note that the flicker peak timing detection method is described in, for example, the above-mentioned Patent Document 1, and thus the description thereof 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 images A and B.

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

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

  Subsequently, the CPU 116 adds the image A and the image B, and obtains an image D shown in FIG. 5 (step S404). Then, the CPU 116 ends the normal flicker detection process. Since the images A and B have a substantially anti-phase relationship with respect to the flicker, the effect of the flicker is reduced in the image D shown in FIG. 5 as a result of the addition process. The image D is used in the process of step S206 shown in FIG.

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

  FIG. 7 is a diagram illustrating an example of flicker waveforms, shutter driving, and images when accumulation and readout are performed at a high frame rate in the camera shown in FIG.

  In FIG. 7, when reading and accumulating, the shutter is driven so that the flicker peak is less than twice to obtain an image A1 and an image B1. Here, the image A1 is an image obtained in the first accumulation and readout, and the image B1 is an image obtained in the second accumulation and readout following the image A1. And it turns out that the influence of the flicker in the image A1 and the image B1 has a substantially reverse phase relationship.

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

  8 and 9, when the flicker detection process for the high frame rate is started, CPU 116 adds image A1 and image B1 to obtain image D1 shown in FIG. 9 (step S801). Since the image A1 and the image B1 are substantially in antiphase with respect to the effect of flicker, the effect of flicker is reduced in the image D1 shown in FIG. 9 as a result of the addition process. The image D1 is used in the process of step S206 shown in FIG.

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

  Further, the CPU 116 obtains a ratio between the image B1 and the image D1 (step S803). Then, the CPU 116 generates an 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 an image C2. These images C1 and C2 show flicker components obtained by continuous accumulation and readout.

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

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

  In the processing of step S805, since the flicker peak is less than twice in the accumulation and readout cycle, the CPU 116 performs flicker peak timing obtained based on the image C1 and flicker peak timing obtained based on the image C2. According to the above, the time difference between peak timings is obtained. 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 predetermined image processing using the image D or the image D1, For example, an image (for example, a live view image) to be displayed on the display 115 is obtained. In this way, it is not necessary to separately obtain an image used in 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 processing other than flicker detection, in addition to display processing for displaying a live view image, for example, photometry processing for subject photometry, color measurement processing for subject color measurement, tracking processing for subject tracking, There is an AF process for focusing on the subject.

  In addition, after performing the process of step S206, the process returns to the process of step S201, and accumulation and reading are performed again. At this time, if it is determined that the flicker is not generated by the process of step S204 or S205, the CPU 116 subsequently reduces the execution frequency of the flicker detection process (that is, lengthens the execution period of the flicker detection (that is, the detection period)). To do).

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

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

  In the above-described embodiment, an image used for processing other than flicker detection and flicker detection is obtained using two images obtained by two accumulations and readouts. However, a plurality of accumulations and readouts are performed. You may make it perform flicker detection. Further, during the flicker detection, a process other than the flicker detection may be performed using the image D1 obtained in the flicker detection process.

  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. Furthermore, although the flicker component is extracted according to the ratio between images, the flicker component may be extracted according to the difference between images.

  In the above-described embodiment, flicker detection is performed using an image obtained from the photometric sensor. However, flicker detection may be performed using an 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 image acquisition means. The CPU 116 functions as a detection unit and a processing unit.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the function of the above embodiment may be used as a control method, and this control method may be executed by the imaging apparatus. 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 apparatus. The control program is recorded on a computer-readable recording medium, for example.

[Other Embodiments]
The present invention supplies a program that realizes 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 This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 102 Shooting lens 103 Focusing lens 104 Aperture 106 Main mirror 108 AF apparatus 109 Viewfinder screen 112 AE apparatus 113 Imaging element 115 Display 116 CPU

Claims (12)

Image acquisition means for capturing the subject at a predetermined first timing to obtain a first image, and capturing the subject at a second timing different from the first timing to obtain a second image When,
When detecting the presence of flicker according to the first image and the second image, when a frame rate for obtaining the first image and the second image exceeds a preset frame rate, Detecting means for detecting the flicker cycle based on the first image, the second image, and a third image obtained as a result of adding the first image and the second image; ,
An imaging device comprising:   The image acquisition means obtains the first image and the second image by controlling the timing of accumulation and readout of the image in an image sensor that outputs an image corresponding to the image of the subject. The imaging apparatus according to claim 1, wherein the timing of 1 and the second timing are in a substantially opposite phase relationship.   When the flicker peak is less than twice in the accumulation and readout cycle in the image acquisition unit, the detection unit sets the frame rate for obtaining the first image and the second image in advance. The imaging apparatus according to claim 2, wherein it is determined that the frame rate exceeds the specified frame rate.   The detection means detects the flicker period based on the first image and the second image when the flicker peak is twice or more in the accumulation and readout period in the image acquisition means. The imaging apparatus according to claim 2 or 3, wherein   5. The image pickup apparatus according to claim 1, wherein when the flicker is not detected, the detection unit lengthens a detection cycle for flicker detection.   The imaging apparatus according to claim 1, further comprising a processing unit that performs other processing using the third image.   The other processing includes photometry processing for measuring the subject, color measurement processing for measuring the subject, tracking processing for tracking the subject, AF processing for focusing on the subject, and live view image display The imaging apparatus according to claim 6, wherein the imaging apparatus performs at least one of display processing.   The imaging apparatus according to any one of claims 1 to 7, wherein the image acquisition unit equalizes an accumulation time when the first image and the second image are obtained.   In the case where the flicker cycle is detected by the detection unit, the image acquisition unit sets the accumulation time for obtaining the first image and the second image to ½ times the flicker cycle. The imaging apparatus according to claim 8, wherein:   When the flicker cycle is not detected by the detection means, the image acquisition means sets an accumulation time for obtaining the first image and the second image to be 1/200 seconds and 1/240 seconds. The imaging apparatus according to claim 8, wherein the time is between. An image acquisition step of capturing the subject at a predetermined first timing to obtain a first image, and capturing the subject at a second timing different from the first timing to obtain a second image When,
When detecting the presence of flicker according to the first image and the second image, when a frame rate for obtaining the first image and the second image exceeds a preset frame rate, A detection step of detecting the flicker cycle based on the first image, the second image, and a third image obtained as a result of adding the first image and the second image; ,
A control method characterized by comprising: A control program used in an imaging apparatus,
In the computer provided in the imaging device,
An image acquisition step of capturing the subject at a predetermined first timing to obtain a first image, and capturing the subject at a second timing different from the first timing to obtain a second image When,
When detecting the presence of flicker according to the first image and the second image, when a frame rate for obtaining the first image and the second image exceeds a preset frame rate, A detection step of detecting the flicker cycle based on the first image, the second image, and a third image obtained as a result of adding the first image and the second image; ,
A control program characterized by causing