JP2018006804A - Imaging apparatus, control method therefor, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate exposure timing to effectively reduce exposure non-uniformity of a picked-up image caused by a flicker even under a flicker light source having distorted waveform characteristics.SOLUTION: An imaging apparatus comprises: an ICPU 112 for detecting the presence/absence and a frequency of a flicker that is a light quantity change of a light from a subject on the basis of multiple photometric values obtained by performing photometry multiple times by photometric means 108, and further calculating timing of a flicker phase to operate a shutter 104 from at least three photometric values among the multiple photometric values; and a CPU 101 for exposing an imaging device 103 by operating the shutter 104 in the timing of the flicker phase calculated by the ICPU. The ICPU applies a low-pass filter having a tap number corresponding to a shutter speed of the shutter to the multiple photometric values and calculates the timing of the flicker phase from the multiple photometric values to which the low-pass filter is applied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus such as a digital camera, and more particularly to a technique for improving exposure unevenness due to flicker (periodic change in the amount of light from a subject).

  In an imaging apparatus such as a digital camera, with a recent increase in ISO, a high-speed shutter can be released even under an artificial light source in which flicker occurs. While high-speed shutter photography has the advantage of being able to take pictures without blurring, such as indoor sports photography, under flickering light sources, image exposure and color unevenness may occur for each frame or within one frame due to the effect of flicker. May occur.

  To solve such a problem, there is a method of reducing the influence of flicker by detecting flicker and performing exposure at the peak position of the flicker with the least change in brightness. For example, a technique has been proposed in which the output timing of the vertical synchronization signal is adjusted so that the influence of line flicker does not occur during AF so that the exposure of the line including the autofocus (AF) area is performed at the flicker peak timing. (Patent Document 1).

JP 2010-103746 A

  By the way, as the flicker light source, there is a flicker light source (see FIG. 6A) having a distorted waveform characteristic in addition to the flicker light source having an ideal Sin waveform characteristic (see FIG. 5A). In the above-mentioned Patent Document 1, for a flicker light source having a distorted waveform characteristic, the exposure at the peak position is not necessarily the optimal timing, and the exposure unevenness that occurs in the captured image cannot be reduced.

  Therefore, the present invention provides an exposure unevenness reduction technique that can calculate an exposure timing that effectively reduces exposure unevenness of a captured image due to flicker even under a flicker light source having a distorted waveform characteristic. Objective.

  In order to achieve the above object, an imaging apparatus of the present invention includes an imaging unit, a shutter that exposes the imaging unit, a photometric unit, and a plurality of photometric values obtained by performing photometry a plurality of times using the photometric unit. And a flicker phase for operating the shutter based on at least three photometric values of the plurality of photometric values. Calculating means for calculating timing; and control means for exposing the imaging means by operating the shutter at the timing of the flicker phase calculated by the calculating means, wherein the calculating means includes the plurality of times A low pass filter having the number of taps corresponding to the shutter speed of the shutter is applied to the photometric value, and the low pass filter to which the low pass filter is applied is applied. And calculates the timing of the flicker phase from times photometric values.

  According to the present invention, it is possible to calculate an exposure timing that effectively reduces exposure unevenness of a captured image due to flicker even under a flicker light source having a distorted waveform characteristic.

1 is a schematic cross-sectional view of a digital single-lens reflex camera that is an example of an embodiment of an imaging apparatus of the present invention. It is a flowchart figure explaining imaging | photography operation | movement of the digital single-lens reflex camera shown in FIG. FIG. 6 is a graph showing a photometric result obtained by continuously performing accumulation / reading 12 times at a cycle of 600 fps and 1.66 ms in order to detect flicker. It is a graph explaining the frequency determination method of flicker. It is a figure explaining the relationship between the shutter travel timing at the time of the high-speed shutter with the waveform of an ideal flicker, and the exposure nonuniformity produced in an image. It is a figure explaining the relationship between the shutter running timing at the time of the high-speed shutter with the waveform of the distorted flicker, and the exposure nonuniformity produced in an image. It is a figure explaining the relationship between the shutter travel timing at the time of a low-speed shutter with the waveform of the distorted flicker, and the exposure nonuniformity produced in an image. It is a figure which shows the waveform which applied the digital low pass filter with respect to the photometry result for a flicker detection. It is a figure which shows a peak synchronizing signal.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a digital single-lens reflex camera as an example of an embodiment of an imaging apparatus of the present invention.

  As shown in FIG. 1, the digital single-lens reflex camera of this embodiment has a replacement lens unit 200 detachably attached to the camera body 100.

  The camera body 100 has a camera CPU 101 that controls the entire camera, and a memory 102 such as a RAM or a ROM is connected to the camera CPU 101. The main mirror 105 and the sub mirror 111 guide the subject luminous flux that has entered the imaging optical path and passed through the lens unit 200 to the focus plate 106 during viewfinder observation, and retract from the imaging optical path to guide the subject luminous flux to the image sensor 103 during imaging. . The main mirror 105 is composed of a half mirror, and the sub mirror 111 reflects a part of the subject light flux that has passed through the main mirror 105 and guides it to the AF unit.

  The penta roof prism 109 converts the subject luminous flux formed on the focusing screen 106 into an erect image of the subject, and the converted subject image is guided to the AE sensor 108 and observed through the optical viewfinder. The display element 107 displays an AF distance measurement frame such as a PN liquid crystal and indicates a position at which the user is focused when looking into the optical viewfinder.

  The image sensor 103 is configured by a CCD sensor, a CMOS sensor, or the like. In the present embodiment, the image sensor 103 has 4000 rows of pixels, and photoelectrically converts a subject image that has passed through the lens unit 200 during imaging to generate an image signal. Output.

  The shutter 104 is controlled by the camera CPU 101 and is closed when not photographing to shield the image sensor 103 and is opened when photographing to guide subject light to the image sensor 103. Further, in this embodiment, the shutter 104 uses a mechanical focal plane shutter that exposes the image sensor 103 by forming a slit in the front curtain and the rear curtain to travel. Here, since the image sensor 103 is composed of 4000 rows of pixels, the front curtain and the rear curtain of the shutter 104 run from the first row to the 4000th row.

  The AE sensor 108 uses not only photometry but also scene recognition such as face detection and flicker detection by using an image sensor such as a CCD sensor or a COMS sensor. Note that flicker detection may be performed by the image sensor 103.

  The ICPU 112 is a CPU for driving control of the AE sensor 108 and image processing / calculation. Based on the photometric results of the AE sensor 108, the ICPU 112 calculates the flicker period and peak timing, which are periodic changes in the amount of light from the subject, in addition to face detection calculations, tracking calculations, photometric calculations, and the like. The light quantity change characteristic is also calculated.

  A memory 113 such as a RAM or a ROM is connected to the ICPU 112. In the present embodiment, the dedicated ICPU 112 for the AE sensor 108 is used. However, all processing of the ICPU 112 may be performed by the camera CPU 101. The LPU 201 is a CPU in the lens unit 200, and sends distance information to the subject to the camera CPU 101.

  Further, in the camera of the present embodiment, when a release button (not shown) is pressed halfway, the release switch SW1 is turned on to perform shooting preparation operations such as AF and AE, and the release button is fully pressed. Then, the release switch SW2 is turned on and the photographing operation is performed.

  Next, with reference to FIGS. 2 to 9, the photographing operation of the digital single-lens reflex camera (hereinafter referred to as a camera) having the above configuration will be described. FIG. 2 is a flowchart for explaining the photographing operation of the camera. 2 are executed by the ICPU 112 by developing a program stored in the ROM or the like of the memory 113 under the control of the camera CPU 101. 2 is executed by the camera CPU 101 by developing a program stored in the ROM or the like of the memory 102 in the RAM.

  In FIG. 2, in step S201, the ICPU 112 performs a photometric operation of the subject using the AE sensor 108, and proceeds to step S202. In the photometry here, it is desirable that the photometric value does not vary with respect to the change in brightness due to the flicker, and the average brightness can be obtained as the photometric value even under a flicker light source.

  Here, the frequency at which the brightness of the flicker light source changes is twice the frequency of the commercial power supply. Therefore, in the power supply region where the power supply frequency is 50 Hz, the frequency is 100 Hz, and the light quantity change period is 10 ms. Similarly, in a region where the power supply frequency is 60 Hz, the frequency is 120 Hz, and the light amount change period is 8.33 ms.

  Even if these flickers exist, if the charge accumulation time is long to some extent, the photometric results are averaged over time, and a stable result can be obtained. On the other hand, when the charge accumulation time is short, the result varies greatly depending on whether the flicker is accumulated at a bright timing or at a dark timing. For this reason, in the case of a short accumulation time equal to or shorter than a predetermined time, a device is required.

  The flicker light amount change period is either 10 ms or 8.33 ms, so when considering about 9 ms between 10 ms and 8.33 ms, the flicker of either frequency is almost in one cycle. Equivalent to. Therefore, when the accumulation time is 9 ms or less, the following processing is performed.

  For example, when it is desired to perform accumulation at an accumulation time of 3 ms, a 9 ms time width corresponding to one flicker cycle is intermittently performed at 3 ms intervals and 1 ms accumulation is performed three times, and an average value thereof is obtained. In this way, by intermittently accumulating, it is not necessary to concentrate on flicker peaks and valleys, so that the average flicker brightness can be obtained as a photometric value even with a short accumulation time. Can do. Here, an example is shown in which 1 ms accumulation is performed three times at an interval of 3 ms and averaged. However, the interval and the number of times are not limited to this, and the time within one cycle of flicker is intermittently accumulated a plurality of times. It is necessary to average the results.

  Based on the photometric value obtained here, the aperture value (AV value), shutter speed (TV value), and ISO sensitivity (ISO value), which are exposure conditions, are determined. The AV value, TV value, and ISO value are determined using a program diagram stored in advance.

  In step S202, the ICPU 112 performs a flicker detection charge accumulation and readout operation, and proceeds to step S203. In the present embodiment, in addition to accumulation for the photometric operation in step S201, accumulation and reading are continuously performed 12 times at a cycle of 600 fps and 1.66 ms as shown in FIG. 3 in order to detect flicker. FIG. 3 shows an ideal 100 Hz flicker with a broken line. If accumulation is performed at an interval of 1.66 ms in this flicker environment, AE (1) to AE (12) which are twelve photometric results are obtained. .

  In step S203, the ICPU 112 determines flicker based on AE (1) to AE (12) that are the photometric results in step S202. In performing flicker determination, a flicker evaluation value is calculated. In this embodiment, the flicker evaluation value used for flicker frequency determination is defined by the following equation using AE (1) to AE (12) obtained in step S202.

  In the above equation, SAD is an abbreviation for Sum of Absolute Difference, and is an index representing the similarity used in the field of pattern matching and the like. For example, when m = 6, the absolute value of the difference between the pair of AE (n) and the six photometric values AE (n + 6) ahead is calculated, and the results for six pairs are added.

  For example, as shown in FIG. 3, if there is a flicker of 100 Hz, the flicker cycle is 10 ms and 10 ms = 1.66 ms × 6, so ideally AE (n) = AE (n + 6 ) Is established. That is, when there is a flicker of 100 Hz, SAD6 = 0. On the other hand, since AE (n) ≠ AE (n + 5), SAD5 when there is a flicker of 100 Hz has a certain large value.

  Similarly, consider 120 Hz flicker. From the relationship of 8.33 ms = 1.66 ms × 5, the relationship of AE (n) = AE (n + 5), AE (n) ≠ AE (n + 6) holds, and when there is a flicker of 120 Hz, SAD5 = 0 , SAD6 has a certain large value.

  On the other hand, in the case of a DC light source that does not have flicker, since the amount of light of the subject is constant, AE (1) = AE (2) = AE (3) = ...... = AE (12) and the 12 photometric values match. To do. That is, SAD6 = SAD5 = 0.

  In addition, it has been assumed that the subject is constant and only the amount of light due to flicker changes so far. For example, when the subject is not constant due to panning or movement of the subject, both SAD6 and SAD5 have large values. Is also possible. In such a case, in the sense of flicker detection error, here, DC determination is performed. Further, since there is no flicker even in sunlight, it is only necessary to be able to determine the presence or absence of flicker. Therefore, here, DC determination is made in the sense that there is no flicker.

  Based on the above characteristics, if the horizontal axis is SAD6 and the vertical axis is SAD5 and the region division shown in FIG. 4 is determined to be 100 Hz / 120 Hz / DC, the presence / absence of flicker and the frequency are detected. Can do.

  Then, according to the flicker determination result, the ICPU 112 proceeds to step S204 if the flicker is 120 Hz, proceeds to step S205 if the flicker is 100 Hz, and proceeds to step S211 if the DC is determined.

  In step S204, the ICPU 112 sets the flicker cycle T = 8.33 ms, and proceeds to step S206. In step S205, the ICPU 112 sets the flicker cycle T = 10 ms, and proceeds to step S206. In step S211, the camera CPU 101 determines whether the release switch SW2 is turned on to give a release instruction. If there is a release instruction, the camera CPU 101 proceeds to step S212, performs an exposure operation by running the shutter 104, and ends the photographing operation. To do.

  In step S206, the ICPU 112 applies a low-pass filter and proceeds to step S207. In step S207, the ICPU 112 performs peak timing calculation processing, and proceeds to step S208. Details of the processing in step S206 and step S207 will be described later with reference to FIGS.

  Steps S206 and S207 are steps for calculating the travel timing of the shutter 104 that can reduce the influence of flicker from the results of AE (1) to AE (12) obtained in step S202. First, the concept of the optimal travel timing of the shutter 104 will be described.

  FIG. 5A is a graph showing the relationship between light quantity and time when observing an ideal 100 Hz Sin waveform flicker, and FIG. 5B is a shutter when exposure is performed at a shutter speed of 1/1000 (1 ms). It is a graph showing driving | running | working.

  When the camera body 100 is held at the normal position, the shutter 104 travels in the order of the front curtain and the rear curtain with the image sensor 103 facing from the top to the bottom. In FIG. 5B, the vertical axis represents the row number of the image sensor 103, and the solid line represents the travel of the leading curtain. As can be seen from the figure, the curtain speed of 3 ms is taken from the first row of the image sensor 103. It is assumed that the vehicle travels a distance up to 4000th line. On the other hand, the broken line in FIG. 5B represents the running of the rear curtain, and the first line of the image sensor is similarly driven at the curtain speed of 3 ms by following the front curtain after a shutter speed of 1 ms. To the 4000th line.

  In this embodiment, the shutter 104 is described as an example of a mechanical shutter, but the same concept can be applied to an electronic rolling shutter. In this case, the curtain speed at the mechanical shutter corresponds to the readout time of the electronic rolling shutter, and the timing of the accumulation operation and readout operation of each row of the image sensor 103 is expressed in the same manner as in FIG. It can be considered in the same way as a mechanical shutter.

  In the exposure of the shutter 104 having the characteristics as shown in FIG. 5B, in this embodiment, the center time of the period during which the 2000th row of the image sensor 103 is exposed is defined as the exposure center. When the exposure center is set to the flicker peak timing t = 5 ms, as shown in FIG. 5A, the exposure amount of the first row of the image sensor 103 and the exposure amount of the 4000th row match, The exposure unevenness due to the inner row is minimized.

  In the example of FIG. 5, the shutter speed was 1/1000 (1 ms), but the flicker light amount waveform is symmetrical with respect to the peak timing. For this reason, the same result is obtained if the exposure center is set to the flicker peak timing of t = 5 ms without depending on the shutter speed. In general, the mechanical shutter does not travel at a constant speed, but gradually accelerates while traveling. Therefore, when the center of the period during which the 2000th row of the image sensor 103 is exposed is the exposure center, the image sensor. The exposure unevenness in the first and 4000th rows increases. Therefore, in consideration of the running characteristics of the mechanical shutter, the row of the image sensor 103 defined as the exposure center may be set so that the exposure unevenness due to the row in the screen is minimized.

  Next, FIGS. 6A and 6B are graphs in the case where there is flicker having a distorted waveform of 100 Hz and the shutter speed is 1/1000 (1 ms). Considering the same as in FIG. 5, when the exposure center is set to t = 6.367 ms, the exposure amounts of the first row and the 4000th row of the image sensor 103 coincide, and the exposure unevenness due to the rows in the screen is minimized. It can be seen that t = 6.367 ms is substantially the same as the peak timing of the light amount shown in FIG.

  On the other hand, FIGS. 7A and 7B are graphs in the case where flicker having a distorted waveform is present and the shutter speed is 1/125 (8 ms). In FIG. 7A, the exposure amount of the first row of the image sensor 103 is indicated by a horizontal line pattern, and the exposure amount of the 4000th row is indicated by a vertical line pattern. Therefore, the partially overlapping region has a lattice pattern. In this case, when the exposure center is set to the time of t = 5.922 ms, the exposure unevenness due to the lines in the screen is minimized. Since this timing is different from the case of FIG. 6, it can be seen that the optimum timing of shutter travel changes depending on the shutter speed.

  Regarding this, in the example of FIG. 6, the shutter speed is relatively high, and the exposure end of the 4000th row from the exposure start of the first row of the image sensor 103 is finished in a short time of 4 ms. Although the flicker waveform in FIG. 6 is distorted, if it is in the vicinity of the peak timing, the light quantity change characteristic is relatively symmetric with respect to the peak timing. Therefore, at the time of high-speed shutter, the exposure center is simply aligned with the peak timing. Thus, almost ideal shutter travel timing is obtained.

  In contrast, in the example of the shutter speed 1/125 (8 ms) in FIG. 7, the time from the start of exposure of the first row of the image sensor 103 to the end of exposure of the 4000th row is as long as 11 ms. In this case, since the influence of the asymmetry of the light quantity change characteristic of flicker has been seen, it can be considered that the optimum timing for shutter travel is deviated from that for high-speed shutter.

  As described above, in the distorted flicker waveform as shown in FIG. 7, the optimal timing for shutter travel may be the flicker peak timing during high-speed shutter. However, as the shutter speed becomes low, it is necessary to observe the change in the amount of flicker light with a wider time width, and to determine the travel timing on that basis.

  Considering the above, in step S206, a moving average or a weighted moving average value is calculated for AE (1) to AE (12) acquired in step S202 according to the TV value (shutter speed) determined in step S201. Then, the peak timing may be calculated.

  Referring to FIG. 8, various low-pass filters (hereinafter referred to as filters) representing moving average and weighted moving average processing are added to AE (1) to AE (12) obtained by measuring the distorted flicker waveform of FIG. An example of calculation when applied will be described.

  In FIG. 8, the waveform S1 is the same as AE (1) to AE (12) (no filter). Waveform S2 is obtained by applying filter coefficients (0, 0.33, 0.33, 0.33, 0) to AE (1) to AE (12). A waveform S3 is obtained by applying filter coefficients (0.125, 0.25, 0.25, 0.25, 0.125) to AE (1) to AE (12).

  For example, if the shutter speed SS is determined to be a high value of SS ≦ 1/500 in step S201, the peak timing of the light amount change may be simply obtained. For this reason, the peak timing is obtained using the values of AE (1) to AE (12) as they are without taking the weighted moving average (waveform S1). As an example of a specific peak timing calculation method, AE (max) obtained the maximum photometric value among AE (2) to AE (11), AE (max-1) one time before and after that, AE Approximate and complement with a quadratic function from the three photometry results of (max + 1). Thereby, the peak timing can be calculated.

  On the other hand, if the shutter speed SS is determined to be a value between 1/500 <SS ≦ 1/160 in step S201, the filter coefficient (0, 0.33, 0.33, 0.33, 0) is determined. ) Is applied (waveform S2). Thereafter, the peak timing may be obtained by complementing with quadratic function approximation.

  Furthermore, when the shutter speed SS is 1/160 <SS of the low-speed shutter in step S201, a filter coefficient (0.125, 0.25, 0.25, 0.25, 0.125) is applied, and the same Perform the calculation.

  When the peak timing t (peak) is obtained by interpolating with the quadratic function approximation for each of the waveforms S1 to S3 in FIG. 8, t (peak) = 6.375 ms when there is no filter of the waveform S1. Further, in the case of the filter coefficient (0, 0.33, 0.33, 0.33, 0) of the waveform S2, t (peak) = 6.137 ms, and the filter coefficient (0.125, 0.25) of the waveform S3. , 0.25, 0.25, 0.125), t (peak) = 5.933 ms. Here, the peak timing t (peak) to be approximately interpolated corresponds to the timing of the flicker phase for operating the shutter of the present invention.

  On the other hand, the optimal shutter travel timing at a shutter speed of 1/1000 is 6.367 ms (≈6.375 ms (waveform S1)), and the optimal shutter travel timing at a shutter speed of 1/250 is 6.221 ms (≈6 .137 ms (waveform S2)). The optimum shutter travel timing at the shutter speed 1/125 is 5.922 ms (≈6.933 ms (waveform S3)). Therefore, it can be seen that by switching the filter, a value closer to the optimum shutter travel timing is obtained according to the shutter speed.

  Although the case where the filter is switched only by the shutter speed is illustrated here, the curtain switching speed of the shutter 104 may be included in the filter switching condition. In addition, although the case where the curtain speed of the shutter 104 is fixed to 3 ms has been described, the curtain speed of the shutter 104 may be changed with the number of times the shutter 104 is used (the number of times of travel).

  In such a case, the curtain speed may be predicted from the relationship between the cumulative number of times the shutter travels and the curtain speed measured in advance, or the curtain speed during shutter travel may be measured for each shutter travel. The curtain speed can be actually measured from the output if a photo interrupter is mounted on the shutter unit, for example. When the curtain speed is known in this way, the value of “shutter speed + curtain speed” may be used as a filter switching condition.

  Furthermore, in the above description, a filter is applied to the photometric values of AE (1) to AE (12) acquired at intervals of 1.66 ms, and 2 is obtained from the maximum photometric result and the photometric results of three points before and after that. The method of calculating the peak timing by approximating and complementing with the following function was shown.

  However, for example, even when the sampling pitch is doubled and AE (1) to AE (24) are acquired at intervals of 0.833 ms, it can be dealt with. That is, the number of taps of the filter is increased by the amount of sampling, and the peak timing is calculated not only for the three-point photometry results but also for the maximum photometry result and the two points before and after that. A method of interpolating with a spline curve from the result is also conceivable.

  That is, the interpolation algorithm for obtaining the filter coefficient, the number of taps, and the peak timing is not limited to the example shown here, and various other algorithms can be considered. By changing the number of taps of the filter and the interpolation algorithm, it is possible to set the filter characteristics more finely, and it can be expected to improve the interpolation accuracy. Then, the ICPU 112 applies the filter in step S206, and when the peak timing calculation ends in step S207, the process proceeds to step S208.

  In step S208, the ICPU 112 generates a flicker synchronization signal from the flicker cycle T set in step S204 or step S205 and the peak timing t (peak) obtained in step S207, and the process proceeds to step S209. As shown in FIG. 9, the flicker synchronization signal is a signal representing the timing of the flicker peak generated at every flicker cycle T with reference to t (peak) obtained in step S207, and is t (peak) + mx. It rises and changes at the timing of T (m is an arbitrary natural number). The ICPU 112 is configured to generate this flicker synchronization signal and transmit it to the camera CPU 101.

  In step S209, the camera CPU 101 determines whether the release switch SW2 is turned on and a release instruction is issued. If there is a release instruction, the process proceeds to step S210.

  In step S210, the camera CPU 101 performs the exposure operation by causing the shutter 104 to travel at a timing such that the exposure center coincides with the rising timing of the flicker synchronization signal (FIG. 9) sent from the ICPU 112, and the photographing operation is performed. finish.

  As described above, in the present embodiment, it is possible to calculate an exposure timing that effectively reduces exposure unevenness of a captured image due to flicker even under a flicker light source having a distorted waveform characteristic.

  In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  The present invention can also be realized by executing the following processing. That is, 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 the computer of the system or apparatus read the program. It can also be realized by processing to be executed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

101 Camera CPU
104 Shutter 108 AE sensor 112 ICPU

Claims (6)

Imaging means;
A shutter for exposing the imaging means;
Photometric means;
Detecting means for detecting the presence and frequency of flicker, which is a change in the amount of light from the subject, based on a plurality of photometric values obtained by performing photometry a plurality of times by the photometric means;
Calculating means for calculating a flicker phase timing for operating the shutter from at least three photometric values of the plurality of photometric values;
Control means for exposing the imaging means by operating the shutter at the flicker phase timing calculated by the calculation means,
The calculating means applies a low-pass filter with the number of taps corresponding to the shutter speed of the shutter to the plurality of photometric values, and calculates the flicker phase timing from the plurality of photometric values to which the low-pass filter is applied. An imaging apparatus characterized by calculating.   The imaging apparatus according to claim 1, wherein the low-pass filter is a moving average or weighted moving average process.   The imaging apparatus according to claim 1, wherein the shutter is a mechanical shutter, and the number of taps of the low-pass filter is determined according to a curtain speed and a shutter speed of the mechanical shutter.   The said shutter is an electronic rolling shutter using the said imaging means, The tap number of the said low-pass filter is determined according to the read-out time and shutter speed of the said electronic rolling shutter, It is characterized by the above-mentioned. The imaging device described. An imaging device control method comprising: an imaging unit; a shutter that exposes the imaging unit; and a photometric unit,
A detection step of detecting the presence and frequency of flicker, which is a change in the amount of light from the subject, based on a plurality of photometric values obtained by performing photometry a plurality of times by the photometric means;
A calculation step of calculating a flicker phase timing for operating the shutter from at least three photometric values of the plurality of photometric values;
A control step of exposing the imaging means by operating the shutter at the flicker phase timing calculated in the calculation step,
The calculating step applies a low-pass filter having the number of taps corresponding to the shutter speed of the shutter to the plurality of photometric values, and calculates the timing of the flicker phase from the plurality of photometric values to which the low-pass filter is applied. A control method for an imaging apparatus, characterized by:   A program for causing a computer to execute each step of the method for controlling an imaging apparatus according to claim 5.