JP5215879B2 - Imaging apparatus, control method thereof, and program - Google Patents

Description

  The present invention relates to a technique for controlling an imaging apparatus such as a video camera.

  2. Description of the Related Art Conventionally, an image pickup apparatus starts an accumulation response operation of an image pickup device in synchronization with a second synchronization signal resulting from a shutter operation that is asynchronous with a frame synchronization signal, so that an object can be instantaneously used in actual use. There is a technique for avoiding a situation where an imaging opportunity is missed. This technique is described in Patent Document 1.

  On the other hand, in an imaging apparatus using an XY address type solid-state imaging device typified by a CMOS image sensor, Patent Document 2 discloses the following measures against fluorescent flicker that appears when a subject under fluorescent lamp illumination is photographed. Technology is disclosed. For example, a fluorescent lamp flicker generated under conditions of a commercial power supply frequency of 50 Hz and a vertical synchronization frequency of 60 Hz has an inter-frame periodicity that returns to the original phase every three frames. For this reason, the flicker correction value for correcting the flicker component is generated from the flicker component detected in the current frame, and the flicker correction value for the subsequent frames is generated by adjusting the phase of the flicker correction value. is there.

Patent Document 3 discloses the following technique. That is, the moving speed of the main subject is obtained from the difference between the current frame and the previous frame and the interval between the frame synchronization signals (hereinafter referred to as the frame period). In addition, the position of the main subject in the next frame is predicted from the moving speed, and an evaluation value frame for automatic focusing is set at that position, thereby keeping the main subject in focus.
Japanese Patent Laid-Open No. 9-247556 JP-A-11-313226 JP-A-8-54556

  FIG. 9 is a diagram illustrating an operation example in which the accumulation operation of the image sensor is started in synchronization with the second synchronization signal resulting from the shutter operation, which is asynchronous with the frame synchronization signal.

  VD1 is a frame synchronization signal, and VD2 is a frame synchronization signal resulting from the shutter operation. In the figure, A, B, D, E, F, and G are moving images, and C is a still image, which are continuously captured in a frame cycle. As for sensor accumulation, moving images are fixed at 1/60 sec (Tsa, Tsb, Tsd, Tse, Tsf, Tsg), and still images are variable depending on the shooting mode. Assumed (Tsc).

  The reading of the sensor depends on the reading clock speed and the number of channels, but the moving image is 1/60 sec or less (Tra, Trb, Trd, Tre, Trf). The still image depends on the number of read pixels, but in this example, the frame period is not exceeded (1/60 sec or less, Trc).

  Storage and readout operations of the image sensor are started with VD1 or VD2 as a trigger. Prior to time ta at which the shutter operation is performed, the accumulation and reading operations of the image sensor are started in synchronization with VD1 (Tsa, Tsb, Tra, Trb). Next, when a shutter operation is performed at time ta, VD2 serves as a trigger, and the accumulation operation of the image sensor is started (Tsc). Thereafter, the image sensor is stored and read with reference to VD2 (Tsd, Tse, Tsf, Tsg, Trc, Trd, Tre, Trf).

  Here, when the accumulation operation of the image sensor is started in synchronization with the second synchronization signal resulting from the shutter operation, which is asynchronous with the frame synchronization signal, the frame period shifts between VD1 and VD2 as shown at t2 in FIG. Arise. In Patent Document 2, even in the case of FIG. 9, for example, the flicker correction values of the image B and the image C are generated by shifting the phase of the flicker correction value acquired from the image A based on the timing of VD1. There was a problem that the correction of C was not properly performed.

  Further, in Patent Document 3, for example, in FIG. 9, the moving speed of the main subject is obtained from the difference between the image A and the image B and the frame period, and the evaluation for automatic focusing is performed on the position of the main subject predicted from the moving speed. An attempt is made to acquire an image C by setting a value frame. For this reason, when the frame period is shifted as shown in FIG. 9, the main subject moves more and deviates from the predicted position, that is, there is a possibility that the evaluation value for automatic focusing cannot be acquired from the main subject.

  Therefore, the present invention has been made in view of the above-described problems, and its purpose is to use a second synchronization signal resulting from a shutter operation asynchronous to the frame synchronization signal even when the frame period is shifted. It is to be able to appropriately perform processing using the periodicity of the frame.

In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes an imaging element that converts a subject image formed by an optical system that forms a subject image into an image signal, and an external signal . in response to the instruction, the first synchronous signal or the first synchronization signal and a driving means for causing the storage operation on the imaging element based on the second synchronization signal of the asynchronous, the image caused by blinking the light source Flicker detection means for detecting a signal level fluctuation component of the signal, flicker correction value estimation means for generating a correction value for correcting the signal level fluctuation component based on a detection result by the flicker detection means, and the flicker correction the correction value generated by the value estimating means, anda flicker correction means for correcting the variation component of the signal level, the flicker correction value estimation means, the first of the imaging device Depending on the accumulation operation by the synchronization signal switching of accumulation operation by the second synchronization signal, and characterized in that changes the correction value in accordance with the phase shift of the first synchronization signal and the second synchronization signal To do.

An image pickup apparatus control method according to the present invention is a method for controlling an image pickup apparatus having an image pickup element for converting a subject image formed by an optical system for forming a subject image into an image signal, from the outside. depending on the instruction, the drive steps the first synchronization signal or the first synchronization signal to perform a storage operation to the image pickup device based on the second synchronization signal of asynchronous, the resulting flashing light source A flicker detection step for detecting a fluctuation component of the signal level of the image signal, a flicker correction value estimation step for generating a correction value for correcting the fluctuation component of the signal level based on a detection result in the flicker detection step, and the flicker A flicker correction step of correcting the fluctuation component of the signal level by the correction value generated in the correction value estimation step. In the flicker correction value estimation step, the imaging In response to the switching of the storage operation by the accumulation operation by the first synchronization signal of the child said second synchronizing signal, the correction value according to the phase shift of the first synchronization signal and the second synchronization signal It is characterized by changing .

  According to the present invention, even when the frame period is shifted by using the second synchronization signal resulting from the shutter operation asynchronous with the frame synchronization signal, it is possible to appropriately perform processing using the periodicity of the frame. It becomes.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to the first embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes an optical system including a lens and an aperture for forming a subject image, 2 an image sensor, 3 an image sensor drive unit, 4 an analog front end unit (AFE) including a CDS circuit and an A / D converter. Is illustrated). Reference numeral 5 denotes a flicker detection unit that detects a flicker component from an image signal that is an output signal of the image sensor 2, and reference numeral 6 denotes a flicker correction value estimation unit that estimates a flicker correction value of the next V (frame) from the detected flicker component. . 7 is a flicker correction unit that corrects flicker using the estimated correction value, 8 is a camera signal processing unit, and 9 is a memory. Reference numeral 11 denotes a recording medium that can be removed from the imaging apparatus, and reference numeral 10 denotes a recording processing unit that records the image data subjected to the inter-frame predictive encoding process on the recording medium 11. Reference numeral 13 denotes a system control unit that controls the entire imaging apparatus and detects external signals, and 12 denotes a bus that communicates between the system control unit 13 and each block in the imaging apparatus. A nonvolatile memory (ROM) 15 stores a program describing a control method executed by the system control unit 13 and control data such as parameters and tables used when the program is executed. Reference numeral 14 denotes a volatile memory (RAM) that transfers and stores the program and control data stored in the nonvolatile memory 15 and is used when the system control unit 13 controls the imaging apparatus.

  Hereinafter, a photographing operation in the imaging apparatus configured as described above will be described.

  Prior to the photographing operation, necessary programs, control data, and correction data are transferred from the nonvolatile memory 15 to the volatile memory 14 and stored at the start of the operation of the system control unit 13 such as when the imaging apparatus is turned on. Shall. These programs and data are used when the system control unit 13 controls the imaging apparatus, and additional programs and data are transferred from the nonvolatile memory 15 to the volatile memory 14 as necessary. Shall. Further, it is assumed that the system control unit 13 directly reads out and uses data in the nonvolatile memory 15.

  First, light from the subject is incident on the image sensor 2 by the optical system 1 and is driven by a drive pulse based on the first synchronization signal from the image sensor drive unit 3 controlled by the system control unit 13. Is converted into an electric signal by photoelectric conversion. The electric signal converted by the image sensor 2 is read out in a raster scan form and converted into a digital image signal by the AFE 4. The digital image signal converted by the AFE 4 uses the flicker correction value calculated by the flicker detection unit 5 and the flicker correction value estimation unit 6 for detecting flicker which is a fluctuation component of the image signal level caused by the blinking light source, and uses the flicker correction value. Flicker correction is performed by the correction unit 7 and output to the camera signal processing unit 8. The image signal that has been subjected to the flicker correction by the flicker correction unit 7 is converted by the camera signal processing unit 8 into an image signal having a luminance color difference. The memory 9 is a part that holds an image subjected to camera signal processing, and is recorded at the synchronization timing from the camera signal processing unit 8 and read out at the synchronization timing of the recording processing unit 10. The recording processing unit 10 compresses and encodes the image signal, converts it into data suitable for the recording medium 11 (for example, file system data having a hierarchical structure), and records the data on the recording medium 11. The system control unit 13 controls the image sensor driving unit 3, the camera signal processing unit 8, and the recording processing unit 10 via the bus 12. Information such as control parameters necessary for each signal processing circuit and a program for controlling the circuit is read from the nonvolatile memory 15 connected to the system control unit 13.

  Next, FIG. 2 shows the configuration of the flicker detection unit 5.

  In FIG. 2, reference numeral 100 denotes a block division unit that sets areas to be detected in the horizontal direction and vertical direction with respect to an image signal, and 101 denotes an addition average part that calculates an average value of each luminance level in the set detection area. . The subtractor 102, the multiplier 103, the adder 104, and the memory 105 form a so-called cyclic low-pass filter by the following calculation.

... (1)
Here, ave represents the output of the averaging unit 101, and mout represents the output from the memory 105. mem indicates an output from the adder 104 and indicates a value newly stored in the memory 105. K is a filter coefficient of the cyclic low-pass filter.

  A divider 106 calculates a flicker component by dividing the image signal and the output from the memory 105.

  Next, flicker correction value estimation when the accumulation operation of the image sensor is started in synchronization with a second synchronization signal that is asynchronous with the first synchronization signal resulting from the shutter operation, which is a characteristic part of the present embodiment. The operation of the unit 6 (operation for changing control) will be described with reference to FIGS.

  First, FIG. 3 is a diagram showing a configuration of the flicker correction value estimation unit 6.

  Reference numeral 200 denotes a flicker characteristic parameter extraction unit that calculates a flicker characteristic parameter from the flicker component (detection result) detected by the flicker detection unit 5. The flicker characteristic parameter is a parameter representing the characteristic of a specific flicker component, and here indicates the phase, amplitude, and frequency of a specific flicker component. Reference numeral 201 denotes a phase adjustment value calculation unit that calculates a phase amount necessary for calculating a flicker correction value for the subsequent frames from the flicker component detected in the current frame. A flicker correction value calculation unit 202 calculates a flicker correction value from the flicker characteristic parameter from the flicker characteristic parameter extraction unit 200 and the phase amount from the phase adjustment value calculation unit 201.

  Next, FIG. 4 shows the control operation of the flicker characteristic parameter extraction unit 200.

  First, in step S100, the detected flicker component is subjected to, for example, Fourier transform represented by Expression (2), Expression (3), and Expression (4).

                                                  ... (2)

                                                  ... (3)

(4)
Here, h indicates a detection frame number in the vertical direction, and y (h) indicates a flicker component value in the h-th detection frame. F represents a frequency, and YRe (f) and YIm (f) represent a real part and an imaginary part when Fourier transform is performed, respectively. Y (f) represents an amplitude component.

  Next, in step S101, f = 50 is applied to the equation (4) to calculate a 50 Hz amplitude component Y50 among the detected flicker components.

  Next, in step S102, f = 60 is applied to Expression (4), and the 60 Hz amplitude component Y60 in the detected flicker component is calculated.

  Next, in step S103, Y50 and Y60 are compared. If Y60 is larger than Y50, the process proceeds to step S104, and the amplitude is set to Y60 and the frequency is set to 60 Hz, and the result is output to the flicker correction value calculation unit 202. On the other hand, if Y60 is Y50 or less, the process proceeds to step S105, where the amplitude is set to Y50 and the frequency is set to 50 Hz, and output to the flicker correction value calculation unit 202.

  The detected flicker component shows a sinusoidal value with the flicker component value 1 as a boundary, for example, as shown in FIG. 5 for each flicker detection frame. Therefore, in step S106, first, the flicker component value for each flicker detection frame is approximated by a straight line. Next, in step S107, all the vertical line number numbers V1, V2, V3,... Where the flicker component waveform approximated by a straight line and the flicker component value 1 intersect are obtained. Next, in step S108, the difference between V1 and V2 is obtained, and it is determined whether the difference is between the threshold values VTh1 and VTh2 (VTh1 <VTh2). If the difference is between the threshold values VTh1 and VTh2, the process proceeds to step S109. In step S109, the inclination of the flicker component waveform at V1 and V2 is obtained. Next, in step S110, the line number indicating a positive value for the obtained slope is output to the flicker correction value calculation unit 202 as a phase.

  On the other hand, if the difference is not between the threshold values VTh1 and VTh2 in step S108, the process proceeds to step S111. In step S111, it is determined whether there is a third intersection V3. If there is V3, the process proceeds to step S112. In step S112, the second intersection point V2 is set as the first intersection point V1, and the third intersection point V3 is set as the second intersection point V2, and the process proceeds to step S108.

  On the other hand, if there is no V3 in step S111, the process proceeds to step S113, where line number 0 is selected as the phase and output to the flicker correction value calculation unit 202.

  Next, FIG. 6 shows the control operation of the phase adjustment value calculation unit 201.

  First, in step S200, it is determined whether a shooting instruction has been detected. If a shooting instruction is detected, the process proceeds to step S201. In step S201, the shift amount of the frame period is acquired from the system control unit 13, and the process proceeds to step S202. In step S202, the amount of phase adjustment is calculated using, for example, the calculation shown in equation (5) using the amount of deviation of the frame period, and the process proceeds to step S204.

Formula (5)
Here, a represents the phase adjustment amount [line], t1 represents the frame period [sec], t2 represents the frame period shift amount [sec], and l represents the total number of lines [line] in the vertical direction. For example, it is assumed that the frame period is shifted by 1/120 [sec] in an imaging apparatus having a frame period of 1/60 [sec] and a total number of vertical lines of 1080 lines. In this case, based on Expression (5), a = ((1/120) × 1080) / (1/60) = 540 [line], and the flicker component is shifted by 540 lines. Therefore, the flicker correction value needs to be shifted by 540 lines. It will be.

  On the other hand, if no photographing instruction is detected in step S200, the process proceeds to step S203. In step S203, since the frame period is not shifted, the phase adjustment amount a = 0 is set, and the process proceeds to step S204. In step S204, the prediction of the phase amount of the flicker correction value using the periodicity for each frame is calculated using, for example, equation (6), and the process proceeds to step S205.

Formula (6)
Here, n is an integer indicating how many frames ahead the flicker correction value calculated from the current frame is applied, where n = 1 for the next frame and n = 2 for the next frame. K represents the total number of lines in the vertical direction. In step S <b> 205, the total amount of phase adjustment is calculated by adding the phase adjustment amount “a” due to the frame period shift and the phase prediction amount “b” due to the periodicity of each frame, and the flicker correction value calculation unit 202 receives the calculation result. Output.

  Also, the flicker correction value calculation unit 202 in FIG. 3 uses, for example, an equation that uses the total amount of phase, amplitude, and frequency output from the flicker characteristic parameter extraction unit 200 and the phase adjustment value from the phase adjustment value calculation unit 201. The flicker correction value Fm is generated using an operation as shown in (7).

Formula (7)
Here, A represents the amplitude, and f represents the frequency of the flicker component. Further, y represents the pixel position in the vertical direction, and l represents the phase. Further, a represents the amount of phase adjustment caused by the frame period shift, and b represents the predicted amount of phase predicted from the periodicity of each frame.

  As described above, in the imaging apparatus using the second synchronization signal resulting from the shutter operation asynchronous with the frame synchronization signal, by generating the flicker correction value in consideration of the frame period deviation amount, Even if the flicker correction values for the next and subsequent frames are calculated from the flicker components detected in step 1, they can be corrected appropriately.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS.

  The configuration of the apparatus according to the present embodiment is substantially the same as that of the first embodiment, and the same members are denoted by the same reference numerals, and the description of the overlapping configuration is omitted.

  The difference from the first embodiment is that instead of the flicker detection unit 5, the flicker correction value calculation unit 6, and the flicker correction unit 7, a mask unit 16, a subject detection unit 17, a mask area estimation unit 18, a memory 19, The AF evaluation value acquisition unit 20 is provided.

  The mask unit 16 is a portion that masks the periphery of the specific subject so that the specific subject is continuously detected, and is a portion that masks the input image according to the position and size from the mask area estimation unit 18 described later. . The subject detection unit 17 is a portion that detects a front face or an oblique face of a person based on the arrangement of facial organs such as both eyes, nose and mouth from the masked input image, and outputs the position and size thereof. is there. The memory 19 holds information on the position and size of the subject (subject information) from the subject detection unit 17 for a predetermined period. The AF evaluation value acquisition unit 20 is a part that sets an evaluation value frame according to the position and size of the subject from the subject detection unit 17 and generates an evaluation value for automatic focusing from within the frame. The mask area estimation unit 18 outputs information about the position and size of the subject from the subject detection unit 17 and information about the position and size to be masked according to the frame period information from the system control unit 13 (detection region). Setting) part.

  Next, refer to FIG. 8 for the control operation of the mask region estimation unit 18 when the accumulation operation of the image sensor is started in synchronization with the second synchronization signal resulting from the shutter operation, which is a characteristic part of the present embodiment. While explaining.

  First, in step S300, since the subject detection operation and the mask area estimation operation are not yet performed, the position Mp (0, 0), the size Ms, which is the same as not masking in the mask unit 16, is performed. Mask by (hmax, vmax). Here, the masking position is represented by the x-coordinate and y-coordinate of the image, and is represented by Mp (x, y). The size to be masked is represented by Ms (v, h) in the vertical v and horizontal h of the area not masked. Hmax and vmax represent the maximum values of the x coordinate and the y coordinate, respectively. Next, in step S301, the subject is detected from the masked input image, and the subject position Fp (x, y) and size Fs (v, h) are output. Here, the position of the subject is expressed as Fp (x, y) in the x and y coordinates of the image, and the size of the subject is expressed as Fs (v, h) in the vertical and horizontal directions. Next, in step S302, it is determined how many subjects are detected as a result of detection by the subject detection unit 17.

  In step S302, if the number is zero, the process returns to step S300, and subject detection is performed again using an unmasked input image. If one person is detected in step S302, the process proceeds to step S304. If two or more people are detected in step S302, the process proceeds to step S303. In step S303, from among the detected two or more subjects, for example, the one close to the center of the image and having the largest size is selected as the specific subject.

  Next, in step S304, an AF evaluation value acquisition frame (frame for generating an evaluation value) is set for the input image according to the position and size from the subject detection unit 17, and the process proceeds to step S305. In step S305, it is determined whether or not the memory 19 holds information on the position and size of the subject before a predetermined time (for example, 1 V (vertical synchronization period)) necessary for estimating the mask area. In step S305, if not held, the process proceeds to step S306, and if held, the process proceeds to step S307.

  In step S306, since the information on the position and size of the subject before a predetermined time (for example, 1V) is not held in the memory 19, a mask area is set by multiplying the size by m at the detected position of the subject. In step S307, information on the position and size of the subject before a predetermined time (for example, 1V) is held in the memory 19, so that the next frame is calculated using the calculations shown in, for example, Expression (8) and Expression (9). The moving speed of the subject is calculated, and the process proceeds to step S308.

                                                Formula (8)

Formula (9)
Here, Eps represents the change speed of the subject position per frame, x and y are the x and y coordinates of the subject position of the current frame, and x ′ and y ′ are the x coordinates of the subject position of the previous frame. And y coordinate. t1 represents a frame period. Ess represents the change speed of the subject size per frame, and v and h represent the vertical and horizontal sizes of the current frame. Further, v ′ and h ′ represent the vertical and horizontal sizes of the previous frame.

  Next, in step S308, it is determined whether a shooting instruction has been detected. If a shooting instruction is detected, the process proceeds to step S309. If a shooting instruction is not detected, the process proceeds to step S310. In step S309, the position and size of the subject of the next frame are calculated using, for example, calculations shown in equations (10) and (11), and the process proceeds to step S312.

                                                Formula (10)

Formula (11)
Here, Eps ′ represents the position of the subject in the next frame, and Ess ′ represents the size of the subject in the next frame. T2 represents the amount of deviation of the frame period.

  In step S310, since no shooting instruction is detected and there is no shift in the frame period, for example, in the calculations shown in Equation (10) and Equation (11), t2 = 0 and the position of the subject in the next frame And size is calculated and it progresses to step S311. In step S311, the calculated position and size of the subject are held in the memory 19, and the process proceeds to step S312. In step S312, a mask area is set using the calculated position and size of the subject, and the process returns to step S301.

  As described above, the second synchronization signal resulting from the shutter operation that is asynchronous with the frame synchronization signal can be obtained by setting the mask region for detecting a specific subject in consideration of the shift amount of the frame period. In the used imaging apparatus, it is possible to perform AF control (focus adjustment control) following a specific subject with high accuracy.

(Other embodiments)
The object of each embodiment is also achieved by the following method. That is, a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded is supplied to the system or apparatus. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but the present invention includes the following cases. That is, an operating system (OS) running on a computer performs part or all of actual processing based on an instruction of a program code, and the functions of the above-described embodiments are realized by the processing.

  Furthermore, the following cases are also included in the present invention. That is, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion card or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the above storage medium, the storage medium stores program codes corresponding to the procedure described above.

1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the flicker detection part of 1st Embodiment. It is a block diagram which shows the structure of the flicker correction value estimation part of 1st Embodiment. It is a flowchart which shows the control operation of the flicker characteristic parameter extraction part of 1st Embodiment. It is a figure which shows an example of the flicker component detected by the flicker detection part. It is a flowchart which shows the control operation of the phase adjustment value calculation part of 1st Embodiment. It is a block diagram which shows the structure of the imaging device concerning the 2nd Embodiment of this invention. It is a flowchart which shows the control operation of the mask area | region estimation part of 2nd Embodiment. It is a figure which shows the operation example which starts the accumulation | storage operation | movement of an image pick-up element synchronizing with the 2nd synchronizing signal resulting from shutter operation asynchronous with a frame synchronizing signal.

DESCRIPTION OF SYMBOLS 1 Optical system 2 Image pick-up element 3 Image pick-up element drive part 4 AFE
DESCRIPTION OF SYMBOLS 5 Flicker detection part 6 Flicker correction value estimation part 7 Flicker correction part 8 Camera signal processing part 9 Memory 10 Recording processing part 11 Recording medium 12 Bus 13 System control part 14 RAM
15 ROM
DESCRIPTION OF SYMBOLS 16 Mask part 17 Subject detection part 18 Mask area | region estimation part 19 Memory 20 AF evaluation value production | generation part 100 Block division part 101 Addition averaging part 102 Subtractor 103 Multiplier 104 Adder 105 Memory 106 Divider 200 Flicker characteristic parameter extraction part 200 Flicker correction value calculation unit 200 Phase adjustment value calculation unit

Claims (9)

An image sensor that converts a subject image formed by an optical system that forms a subject image into an image signal;
In response to an instruction from the outside, a drive means for causing the storage operation on the imaging element based on the second synchronization signal of the asynchronous to the first synchronization signal or the first synchronization signal,
Flicker detection means for detecting a fluctuation component of the signal level of the image signal caused by the blinking light source;
Flicker correction value estimating means for generating a correction value for correcting the fluctuation component of the signal level based on a detection result by the flicker detecting means;
Flicker correction means for correcting the fluctuation component of the signal level by the correction value generated by the flicker correction value estimation means,
The flicker correction value estimating unit is configured to switch the first synchronization signal and the second synchronization signal in accordance with switching between the accumulation operation by the first synchronization signal and the accumulation operation by the second synchronization signal of the image sensor. An image pickup apparatus, wherein the correction value is changed according to a phase shift. The imaging apparatus according to claim 1, wherein the second synchronization signal is a signal resulting from a shutter operation. The imaging apparatus according to claim 1, wherein the second synchronization signal is a signal resulting from a shooting instruction. 4. The imaging apparatus according to claim 1, wherein the first synchronization signal is a frame synchronization signal of a frame that is repeatedly output from the image sensor at a predetermined cycle. 5. A subject detecting means for detecting a specific subject information from the previous SL image signal, a detection area setting means for setting a region for detecting the specific subject information, the predetermined time period specific subject information detected by the subject detecting means Holding means for holding, evaluation value generating means for generating an evaluation value for focus adjustment of the optical system, and focus adjustment control means for controlling the focus adjustment based on the evaluation value, and the subject detecting means, the first sync signal according to the accumulation operation and switching of the accumulation operation by the second synchronization signal by, wherein the benzalkonium change the region to detect the specific subject information of the imaging device The imaging apparatus according to claim 1. The change of the area for detecting the specific subject information is to change the size of the area to be detected according to a phase shift between the first synchronization signal and the second synchronization signal. The imaging device according to claim 5 . The change of the area for detecting the specific subject information is to change the position of the area to be detected according to a phase shift between the first synchronization signal and the second synchronization signal. The imaging device according to claim 5 . A method for controlling an image pickup apparatus having an image pickup element for converting a subject image formed by an optical system for forming a subject image into an image signal,
In response to an instruction from the outside, and a driving step for performing the storage operation on the imaging element based on the second synchronization signal of the asynchronous to the first synchronization signal or the first synchronization signal,
A flicker detection step of detecting a fluctuation component of the signal level of the image signal caused by the blinking light source;
A flicker correction value estimation step for generating a correction value for correcting the fluctuation component of the signal level based on the detection result in the flicker detection step;
A flicker correction step of correcting the fluctuation component of the signal level by the correction value generated in the flicker correction value estimation step,
In the flicker correction value estimation step, the first synchronization signal and the second synchronization signal according to switching of the accumulation operation by the first synchronization signal and the accumulation operation by the second synchronization signal of the image sensor. A method for controlling an imaging apparatus, wherein the correction value is changed according to a phase shift. A program for causing a computer to execute the control method according to claim 8 .

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