Electronic device and control method thereof

Abstract

To perform flicker detection depending on a purpose.SOLUTION: An electronic apparatus comprises: an image sensor having a plurality of pixels which is divided into a plurality of pixel groups including a first region and a second region, and capable of actuating each region with shooting conditions independently set for each region; and control means that switches between a first actuation in which the first region and the second region are actuated with same shooting conditions and a second actuation in which the first region and the second region are actuated with shooting conditions different from each other; detection means that detects flicker on the basis of a signal read out from the image sensor; and in the second actuation, the control means controls to actuate the second region with shooting conditions for detecting the flicker, and the detection means detects the flicker on the basis of a signal for detection read from the second region.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an electronic device capable of capturing images and a control method thereof, and in particular to a technique for detecting flicker. [Background technology]

[0002] When taking pictures with a digital camera, mobile phone, camcorder, etc., the light source in the shooting environment can affect the brightness of a single image or between consecutively taken images. When the light source is lighting that uses commercial power, flickering occurs, which is a phenomenon in which the lighting light periodically fluctuates due to the influence of the commercial power frequency. When taking pictures under a light source that causes such flickering (hereinafter referred to as a "flickering light source"), uneven exposure and color can occur within a single image, and variations in exposure and color temperature can occur between multiple images taken in succession.

[0003] For flicker that occurs when the power supply frequency is 50 Hz, the flicker light source blinks at 100 Hz, so the flicker can be corrected by controlling the charge accumulation time to N / 100 seconds (N is a natural number). For flicker that occurs when the power supply frequency is 60 Hz, the flicker light source blinks at 120 Hz, so the flicker can be corrected by controlling the charge accumulation time to N / 120 seconds. In this way, if it is possible to determine whether the frequency that is occurring is 50 Hz or 60 Hz, the impact of flicker on image quality can be reduced.

[0004] Also, a technique for analyzing the change in the amount of light in continuously captured images and identifying the frequency of the occurring flicker has been known. Patent Document 1 discloses a technique for detecting flicker by switching the shooting conditions such as the driving cycle and exposure conditions of an image capturing device from normal shooting conditions to shooting conditions for flicker detection so that flicker can be detected well. However, since the detection is performed by switching from the normal shooting conditions, it is not possible to detect flicker during video shooting or while displaying a live view image.

[0005] Patent Document 2 discloses a method for detecting the frequency of flicker occurring in a subject while displaying a live view image or shooting a video. In this method, a second pixel row is read out at a different timing and cycle from the first pixel row, separately from the first pixel row used for live view display or motion shooting, and the image signal of the second pixel row is used to analyze the flickering of a light source. For example, the frame rate and exposure time of the second pixel row can be set to conditions that make it easy to detect flicker, and an image signal can be obtained.

[0006] For example, if the flicker frequency is 120 Hz, and the video frame rate is set to 60 fps, it will be synchronized with the 120 Hz flicker, and the effect of blinking between frame images will not change from frame to frame, so flicker cannot be detected from the image signal obtained from the first pixel row. On the other hand, the second pixel row can be set to a condition that allows good flicker detection, so by reading out the image signal at, for example, 90 fps, which is not synchronized with either the 100 Hz or 120 Hz flicker, flicker of either frequency can be detected well. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6225000 [Patent Document 2] JP 2020-80512 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in recent years, the performance of image sensors has improved, and image sensors capable of high-speed image signal readout are now available. For example, in video shooting, it is now possible to record slow motion at 120 fps or more, and in live view display, it is now possible to capture and display smooth images with little delay at 120 fps or 240 fps.

[0009] In such an image sensor, when a video is captured at a frame rate shorter than the flicker period of 100 Hz or 120 Hz, the charge accumulation time of each frame image of the video cannot be set to N / 100 seconds or N / 120 seconds. Therefore, flicker caused by the blinking of the light source cannot be corrected by adjusting the charge accumulation time. Therefore, as shown in Patent Document 2, although it is possible to detect the presence or absence and frequency of flicker by analyzing the change in the image signal from the second pixel row, it is not possible to correct the flicker that appears in the image obtained from the first pixel row.

[0010] Furthermore, the flicker detection method of Patent Document 2 has a problem in that it consumes more power than the method of Patent Document 1 and conventional methods.

[0011] The present invention has been made in consideration of the above problems, and has an object to perform flicker detection according to a purpose. [Means for solving the problem]

[0012] In order to achieve the above object, the electronic device of the present invention includes an image sensor including a plurality of pixels, the plurality of pixels being divided into a plurality of regions including a first region and a second region, and capable of being driven under a shooting condition set for each region; a control means for switching between a first drive for driving the first region and the second region under the same shooting condition and a second drive for driving the first region and the second region under mutually different shooting conditions; and a detection means for detecting flicker based on a signal read out from the image sensor. a determination unit that determines whether or not the detection unit is capable of detecting flicker based on a signal read from the image sensor by the second driving; having When the determination means determines that flicker can be detected based on the signal read from the image sensor by the second driving,In the second driving, the control means controls to drive the second area under shooting conditions for detecting flicker, and the detection means detects flicker based on a detection signal read out from the second area. Effect of the Invention

[0013] According to the present invention, flicker detection can be performed according to the purpose. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic configuration of a digital mirrorless camera according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of a pixel array in an image sensor according to an embodiment. [Diagram 3] 5A to 5C are diagrams for explaining generation of a moving image and an image for flicker detection from the pixel arrangement of an image sensor in the embodiment. [Figure 4] FIG. 6 is a timing chart of moving image scanning and flicker detection scanning during the second driving mode in the embodiment. [Diagram 5] 5A to 5C are diagrams showing features of flicker detection from a moving image and from a flicker detection image in the embodiment. [Figure 6] 5 is a conceptual diagram showing a method of correcting flicker when an image sensor is driven by a rolling shutter system in the embodiment. [Figure 7] 5 is a conceptual diagram showing a correction method when an image sensor is driven by a global shutter method in the embodiment. [Figure 8] 5 is a flowchart showing a flicker detection control and coping method according to the first embodiment. [Figure 9] 10 is a flowchart showing flicker detection control in the second embodiment. [Figure 10] A diagram summarizing the processing shown in FIG. [Figure 11] 10 is a flowchart showing flicker detection control in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0016] In this embodiment, a digital mirrorless camera will be described as an example, however, the present invention can be applied to various electronic devices that have a live view image display and a video shooting function, such as smartphones, camcorders, and camera-equipped game consoles.

[0017] FIG. 1 is a diagram showing a schematic configuration of a digital mirrorless camera in an embodiment of the present invention, and mainly includes a camera body 100 and a photographing lens 200. In the camera body 100, 101 is an image sensor such as a CCD or CMOS including an infrared cut filter and a low-pass filter, and an image of a subject is formed on a light receiving surface by the photographing lens 200. The image sensor 101 photoelectrically converts the image of the subject that is received, and an image based on the obtained electrical signal is displayed as a live view or recorded as a photographed image. The electrical signal obtained from the image sensor 101 is also used for detecting flicker. A method of detecting flicker using this electrical signal will be described in detail later. The image sensor 101 can control the charge accumulation time according to the shutter speed set as the photographing setting information.

[0018] The display unit 102 is composed of, for example, a TFT liquid crystal panel. During framing, an image acquired by the image sensor 101 and various shooting setting information are displayed in real time to realize a live view. Also, a captured image can be displayed in response to a user's operation so that the user can check it. A touch panel may be disposed on the display unit 102 and used as an operation member, and a function linked to the display of the touched position can be operated by the touch panel detecting a user's touch operation on an icon or the like displayed on the display unit 102.

[0019] The CPU 103 controls each section of the camera body 100. The CPU 103 also controls the image sensor 101 and the display unit .

[0020] Next, the photographing lens 200 will be described. Reference numeral 201 denotes a lens group including a focus lens, and focus can be adjusted by driving the focus lens. In FIG. 1, the lens group 201 is represented by a single lens, but in reality it is made up of multiple lenses. Reference numeral 202 denotes an aperture, which adjusts the amount of light taken into the camera. Reference numeral 203 denotes a CPU that controls each part of the photographing lens 200, and in addition to controlling the lens group 201 and aperture 202, it can exchange information such as the focus position and aperture with the camera body 100 by communicating with the CPU 103 on the camera body 100 side.

[0021] Next, a method for driving the image sensor 101 in this embodiment will be described. FIG. 2 is a diagram showing a pixel arrangement of the image sensor 101, and as an example, the pixel arrangement is a Bayer arrangement. The image sensor 101 of this embodiment has a configuration that can be controlled independently on a row-by-row basis. Then, a first drive in which all pixels of the image sensor 101 are driven under the same shooting conditions, and a second drive in which a first pixel row (first region) and a second pixel row (second region) are driven under different shooting conditions can be selectively performed. In the first drive, driving by a readout method that has been generally performed in the past is possible, and control may be performed to read signals from all pixels, or control may be performed to read signals by thinning and / or adding readout. Specifically, the readout method may be changed depending on the use of the read signal, the resolution and shooting mode set by the user, the standard of the output destination, the power state of the camera body 100, and the like.

[0022] Next, the second driving method will be described with reference to FIG. FIG. 3(a) shows the concept of a method for generating a moving image for recording or display by reading out signals of a first pixel row from the pixel arrangement shown in FIG. 2. FIG. 3(b) shows the concept of a method for generating an image used for detecting flicker (hereinafter referred to as a "flicker detection image" (detection signal)) by reading out signals of a second pixel row from the pixel arrangement shown in FIG. 2. In this embodiment, the same read control is repeated for three pixel rows as one control unit. First, of the first three rows, the first and third rows are read out as the first pixel row, and the second row is read out as the second pixel row. Then, of the next three rows, the fourth and sixth rows are read out as the first pixel row, and the fifth row is read out as the second pixel row.

[0023] By repeating this control, signals are read out from the first pixel row at a 2 / 3 thinning rate, so that signals with the same color arrangement for two consecutive rows are read out, as shown in the center of Figure 3(a). In the following explanation, this readout scanning is called "moving image scanning." If the signals read out by this moving image scanning are added for two rows in the vertical direction, as shown on the right of Figure 3(a), an R' signal is generated from the R signals of two consecutive pixels in the vertical direction, a G' signal is generated from the G signals of two pixels, and a B' signal is generated from the B signals of two pixels. The moving image composed of the R', G', and B' signals generated in this way returns to the Bayer array, making it possible to perform image processing in the same way as for normal images.

[0024] Moreover, signals are read out from the second pixel row at a 1 / 3 reduction rate, resulting in a Bayer array flicker detection image as shown on the right side of Figure 3(b). In the following explanation, this readout scan is called "flicker detection scan."

[0025] Although only the pixel arrangement of the XY address system is mentioned here, the present invention is not limited to this. As long as the image sensor can be controlled independently on a row-by-row basis, the second driving can be performed whether it is a global shutter system such as a CCD or a rolling shutter system such as a CMOS.

[0026] FIG. 4 is a diagram showing an example of the timing of moving image scanning and flicker detection scanning, where the horizontal axis indicates time and the vertical axis indicates the vertical position (row) of the image sensor 101. The solid diagonal lines indicate the timing of moving image scanning, and the dashed diagonal lines indicate the timing of flicker detection scanning. In the example shown in FIG. 4, during one frame period of a moving image, first, moving image scanning is performed once, and then flicker detection scanning is performed multiple times. Note that flicker detection scanning does not necessarily have to be performed in each frame, and may be performed, for example, every several frames. Also, the number of times flicker detection scanning can be performed in each frame varies depending on the shooting conditions and the function of the image sensor 101, but moving image scanning is performed once per frame period. Also, moving image scanning does not necessarily have to be performed first, and may be performed, for example, after flicker detection scanning.

[0027] Next, the features of a flicker detection method from a flicker detection image obtained by flicker detection scanning and a conventional flicker detection method from a moving image will be described with reference to the table in FIG.

[0028] First, regarding the question "Do shooting conditions affect image quality?", flicker detection scanning can be performed using shooting conditions such as exposure time that are different from those for moving image scanning, which makes it easier to detect flicker. Moving image scanning must be performed according to the specifications of the display device and recording method, the camera settings, the user settings, etc., in order to obtain a moving image, but flicker detection images are neither displayed nor recorded, so flicker detection scanning can be performed under any shooting conditions.

[0029] Next, regarding the question "Is 50Hz / 60Hz detectable?", the answer is as follows: For moving images, the mainstream video formats are the NTSC (National Television System Committee) video format and the PAL (Phase Alternating Line) format. NTSC is standardized for transmission of 29.97 frames per second (≒30fps), while PAL is standardized for transmission of 25 frames per second, which are synchronized with 120Hz / 100Hz flickering, respectively. As a result, when detecting flicker using moving images, it is not possible to detect either 100Hz or 120Hz flickering.

[0030] On the other hand, in flicker detection scanning, the shooting conditions can be freely determined as described above. Therefore, by driving at, for example, 90 fps or 180 fps that is not synchronized with the 120 Hz / 100 Hz flickering, it is possible to detect both 100 Hz flicker and 120 Hz flicker using the obtained flicker detection image.

[0031] Next, the correction method will be described. As described above, it is known that an image with the influence of flicker suppressed can be captured by setting the charge accumulation time to an integer multiple of the flicker cycle. In other words, whether flicker is detected from a moving image or a flicker detection image, the flicker can be corrected by setting the charge accumulation time of the moving image to an integer multiple of the detected flicker cycle according to the frequency of the detected flicker.

[0032] However, when the frame rate is high, it may not be possible to set it to an integer multiple of the flicker cycle. For example, if flickering of 100 Hz is detected while shooting a moving image at 120 fps, 1 / 100 seconds is longer than the driving cycle of 120 fps, so it is not possible to control the charge accumulation time to an integer multiple of the flicker cycle, which would allow flicker correction. This is also true for even higher speed shooting such as 200 fps or 240 fps. In such cases, flicker can be corrected by applying image correction (gain) to the moving image to cancel the effect of flicker, rather than exposure time. Note that the method of image correction differs between rolling shutter images and global shutter images.

[0033] Figure 6 is a conceptual diagram showing a correction method using image processing for an image captured using the rolling shutter method. With the rolling shutter method, the charge accumulation timing differs for each row, and so the amount of light received by each row differs due to the flickering of the light source. As a result, the brightness fluctuates in the vertical direction of the image, as shown in Figure 6(a). Flicker can be corrected by analyzing this brightness fluctuation (Figure 6(b)) and performing image processing to multiply each row by a digital gain (Figure 6(c)) that is the reciprocal of the vertical brightness change (Figure 6(d)).

[0034] Next, a conceptual diagram of a correction method for video images captured using the global shutter method is shown in Figure 7. In the global shutter method, charge accumulation begins and ends for all lines of each frame image at the same timing, so there is no change in luminance due to flicker within each frame image. However, when analyzing the luminance of multiple images captured continuously in the time direction, the amount of light received differs for each frame image due to the flickering of the light source (Figure 7(a)), so when the captured video images are viewed continuously, the luminance fluctuates between the frame images (Figure 7(b)). Therefore, the fluctuation in luminance between frame images is analyzed (Figure 7(c)), and a correction gain that cancels the effect of flickering (Figure 7(d)) ​​is applied to each frame image to make the brightness between the frame images uniform (Figure 7(e)). This makes it possible to correct the flicker when viewed continuously.

[0035] Here, when flicker is detected using the flicker detection image, it cannot be corrected by gain. This is because the flicker detection image is shot under different shooting conditions than the moving image, and the flicker detection image is affected differently by the flickering of the light source than the moving image. The number and density of stripes differ between the flicker detection image and the moving image if the rolling shutter method is used, and the period of luminance change and the amplitude that appears in the image differ if the global shutter method is used. Therefore, even if the presence or absence of 100 Hz or 120 Hz flickering can be detected from the flicker detection image, it is not possible to calculate the gain (image processing coefficient) to be applied to the moving image.

[0036] Finally, the power consumption is as follows. That is, when comparing the presence and absence of flicker detection scanning, the power consumption of the image sensor 101 increases when flicker detection scanning is performed compared to when it is not performed. Also, when only the first driving or moving image scanning is performed, the power consumption is unchanged compared to the conventional method. Therefore, when flicker detection scanning is performed, the battery will run out faster and the number of shots that can be taken will decrease compared to when flicker detection scanning is not performed.

[0037] Considering the above-mentioned features of flicker detection from a moving image and flicker detection from an image for flicker detection, in the first embodiment, the control shown in Fig. 8 is performed based on whether flicker correction is possible. Fig. 8 is a flowchart showing flicker detection and measures against flicker in still image live view mode or moving image mode. Note that the control shown in Fig. 8 is started when the still image live view mode or moving image mode is started.

[0038] First, in S100, it is determined whether the second drive is possible. As described above with reference to Figs. 2 to 4, the second pixel row not used for generating the moving image is used for generating the image for flicker detection. However, in an all-pixel readout mode, for example, a high-resolution 4K moving image mode, the second pixel row cannot be secured, and therefore the second drive cannot be performed. In such a case, the first drive is started in S107, flicker detection is performed using the obtained moving image in S108, and the presence or absence of flicker is determined in S109. Note that this includes both a case where there is no actual flicker and a case where the flicker cannot be detected even if there is a flicker, as described above.

[0039] If flicker is detected, the process proceeds to S110, where the flicker in the moving image is corrected by the charge accumulation time or gain. On the other hand, if no flicker is detected, the process proceeds to S112, where it is determined whether or not to end the shooting. If the shooting is not to end, the process returns to S108, and the next input image is Above The above process is repeated, and when shooting is to be ended, the process is ended.

[0040] On the other hand, if it is determined in S100 that the second driving is possible, the second driving is started in S101. Then, from the flicker detection image acquired by the second driving, flicker detection is performed in S102 to determine whether or not flicker is present. If no flicker is detected, the process proceeds to S111.

[0041] If flicker is detected in S102, the process proceeds to S103, where it is determined whether the flicker can be corrected by controlling the charge accumulation time. Whether the flicker can be corrected by controlling the charge accumulation time is determined by the frame rate of the moving image scanning and the frequency of the detected flicker. For example, if the frame rate of the moving image scanning is 120 fps and a flicker of 120 Hz is detected, the flicker can be corrected by setting the charge accumulation time to 1 / 120 seconds. On the other hand, if a flicker of 100 Hz is detected at 120 fps, it is determined that the flicker cannot be corrected because the charge accumulation time cannot be set to 1 / 100 seconds. In other words, the flicker cycle is compared with the frame rate, and if the flicker cycle is equal to or less than the frame rate, it is determined that the flicker can be corrected by controlling the charge accumulation time. If the answer is YES in S103, the charge accumulation time of the moving image scanning is set to a charge accumulation time (an integer multiple of the flicker cycle) that allows the flicker to be corrected in S104, and the process proceeds to S111.

[0042] On the other hand, if it is determined in S103 that the flicker cannot be corrected even if the charge accumulation time is controlled, in S105, the luminance of the moving image is analyzed to detect the flicker, and a gain value to be applied to the moving image by image processing is calculated. Then, in S106, the flicker of the moving image is corrected by image processing using the calculated gain value, and the process proceeds to S111.

[0043] In S111, it is determined whether or not to end the shooting. If not, the process returns to S102, and flicker detection is performed on the next input flicker detection image. If it is to end, the process ends.

[0044] As described above, according to the first embodiment, when the image sensor has a configuration capable of acquiring a flicker detection image from a partial region thereof, the flicker detection method is changed in accordance with the flicker correction method, which makes it possible to obtain moving images with less flicker effects under a wider range of shooting conditions.

[0045] <Second embodiment> Next, a second embodiment of the present invention will be described. Note that the device configuration in the second embodiment is similar to that in the first embodiment, so the description will be omitted.

[0046] In the second embodiment, the control for switching the driving method from the viewpoint of power consumption described with reference to FIG. 5 will be described with reference to the flowchart of FIG.

[0047] First, in S200, it is determined whether the second drive is possible. For example, in the case of a setting related to a drive for reading out a moving image such as a 4K video mode, the second drive for performing a scan for detecting flicker cannot be performed. In addition, since the second drive accompanied by a scan for detecting flicker consumes a large amount of power, in the second embodiment, the second drive is not performed in the case of a camera setting that prioritizes saving power such as a power saving priority setting.

[0048] If the second driving cannot be performed, the process proceeds to S211 and the first driving is started. As described above, in the first driving, all pixels of the image sensor 101 are driven under the same shooting conditions, but it is not necessary to read out all pixels, and thinning-out reading or additive reading may be performed according to the required resolution. In the next S212, flicker detection is performed using the moving image obtained by the first driving, and the process proceeds to S213.

[0049] On the other hand, if the second drive is possible, the power status of the camera is checked in S202 and S203. If power is being supplied from an external source via a power cable, USB cable, etc. (YES in S202), there is no problem with power consumption due to the second drive, so the process proceeds to S205 and the second drive is started. Here, for example, flicker detection scanning is performed at 0.2 second intervals. Then, the process proceeds to S208.

[0050] On the other hand, if there is no external power supply and the remaining battery power is below a predetermined threshold T b1If it is less than 10%, for example (YES in S203), it is assumed that there is no power margin, and the process proceeds to S211, where the first driving described above is started. Then, in S212, flicker detection is performed using the moving image obtained by the first driving, and the process proceeds to S213.

[0051] In S213, it is determined whether or not to end the shooting. If the shooting is not to be ended, the process returns to S212, where flicker is detected in the next input image, and if the shooting is to be ended, the process ends.

[0052] In addition, in S203, even if there is no power supply from the outside, the remaining battery power is determined to be equal to or lower than a predetermined threshold T b1 If the battery level is greater than 10%, for example (NO in S203), the battery is not in a particularly low power state, so the process proceeds to S204 to further determine the remaining battery level. b2 If the power state has more margin (for example, 50%) (in the range of 50 to 100%), the process proceeds to S206, where the second driving is started. Here, for example, flicker detection scanning is performed at one second intervals. Then, the process proceeds to S208.

[0053] In S208, flicker detection is performed using only the flicker detection image, and the process proceeds to S210.

[0054] On the other hand, when the remaining battery power exceeds a predetermined threshold T b2 In the following cases (range of 10 to 50%) (YES in S204), since there is some power margin but it is desired to reduce power consumption, the process proceeds to S207 and the second drive is started. Here, for example, flicker detection scanning is performed at intervals of 10 seconds. Then, the process proceeds to S209. In S209, flicker detection is performed using the flicker detection image when there is a flicker detection image, and using a moving image when there is no flicker detection image, and then the process proceeds to S210.

[0055] In S210, it is determined whether or not to end the shooting. If the shooting is not to be ended, the process returns to S202 and the above-mentioned processing is repeated, and if the shooting is to be ended, the process ends.

[0056] The process of FIG. 9 described above is summarized in FIG. 10. When power is being supplied from an external source, there is no need to worry about the remaining battery charge, so flicker detection scanning is performed in the second drive at a first interval (e.g., 0.2 second intervals) which is more frequent. Then, flicker detection is performed using only the flicker detection image. On the other hand, when there is sufficient battery charge (e.g., 50% to 100%) even if there is no external power supply, flicker detection scanning is performed in the second drive at a second interval (e.g., 1 second intervals) which is less frequent than when power is being supplied from an external source. Then, flicker detection is performed using only the flicker detection image.

[0057] Furthermore, when there is no external power supply and the remaining battery level is low (10% to 50%), the interval for performing flicker detection scanning in the second drive is further extended to a third interval (for example, 10 seconds) to prioritize power consumption reduction. Then, when a flicker detection image is generated, flicker detection is performed using the flicker detection image, and during that time, flicker detection is performed using a moving image.

[0058] As explained in Figure 5, flicker detection using moving images can only detect either 50 Hz or 60 Hz, and if images for flicker detection cannot be acquired, there will always be frequencies that cannot be detected. Therefore, by periodically performing flicker detection scanning even at longer intervals and constantly performing detection from moving images during that time, it is possible to achieve well-balanced flicker detection that reduces power consumption while not drastically reducing detection accuracy.

[0059] In addition, when there is no external power supply, the remaining battery charge is extremely low (10% or less), and the second operation is not possible, the reduction of power consumption is given top priority, so the second operation is not performed and flicker detection is performed using moving images obtained by normal shooting.

[0060] In the second embodiment, an example is shown in which the flicker detection scan is performed periodically at a fixed time interval, but it does not necessarily have to be performed periodically. For example, a control may be adopted in which a change in the subject is determined from a moving image and the flicker detection scan is resumed when the change occurs, or a control may be adopted in which a change in the flicker level is determined from the flicker detection result using the moving image and the flicker detection scan is resumed. By performing the flicker detection scan constantly or depending on the conditions while flicker detection using the moving image is being performed, it is possible to realize a relatively good flicker detection performance while suppressing power consumption.

[0061] In addition, in the present embodiment, 10% and 50% of the remaining battery capacity are given as examples of threshold values ​​for switching the flicker detection control, but other percentages may be used. Also, the percentage may be switched depending on the camera settings, for example, between video mode and still image mode.

[0062] As described above, according to the second embodiment, the flicker detection method is changed depending on the power supply state, thereby making it possible to perform good flicker detection according to the power supply state.

[0063] Depending on the cycle of the detected flicker, correction can be performed as described in S103 and subsequent steps in FIG. 8 of the first embodiment.

[0064] <Modification> In the first and second embodiments, the process of performing flicker detection scanning while capturing a moving image has been described, but flicker detection may be performed while the camera is in a blackout state. For example, it may be performed during a blackout immediately after powering on, or during a blackout while capturing a still image by pressing the release button. In detecting flicker during a blackout, since the captured image is not displayed on the display unit 102, detection may be performed using a moving image, detection may be performed using an image for flicker detection, or flicker detection may be performed using another method.

[0065] Books Variations Now, including such a case, the overall flow of flicker detection control processing from power-on to camera state transition will be described with reference to the flowchart of FIG.

[0066] First, in S300, flicker detection is performed during blackout at startup. Next, in S301, it is determined whether the mode after startup is still image mode or video mode. In the case of still image mode, in S302, the frame rate of the live view display is determined, and if the frame rate is 120 fps or higher, in S305, the second drive is performed in which the above-mentioned flicker detection scan is performed at a third interval, and both flicker detection using a video image and flicker detection using an image for flicker detection are performed to determine whether flicker exists.

[0067] Also, the frame rate of the live view display on the S302 is 120fps. s If it is less than this, the power state is determined in S303. If power is being supplied from an external source or there is sufficient battery power remaining, the process proceeds to S304, where the second drive is performed in which the above-mentioned flicker detection scan is performed at the first interval or the second interval, and flicker detection is performed using only the flicker detection image. If power is not being supplied from an external source but there is a certain amount of battery power remaining, the second drive is performed in S305 in which the above-mentioned flicker detection scan is performed at a third interval, and flicker detection is performed using both the flicker detection image and the moving image. If power is not being supplied from an external source and there is not sufficient battery power remaining, the first drive is performed in S306, and flicker detection is performed using only the moving image.

[0068] If a still image capture instruction is received during live view display in S307, flicker detection is performed at the timing when the live view display switches to still image capture in S308, and then still image capture is performed in S309. After still image capture is completed, the process returns to S301 again to determine whether the mode is still image or video mode.

[0069] Next, a case where the video mode is determined in S301 will be described. In the video mode, since flicker detection scanning is not possible in a driving mode that does not allow thinning readout, such as 4K video, it is determined in S310 whether flicker detection scanning is possible. If flicker detection scanning is not possible, the first driving is performed in S315, and flicker detection is performed using only the video image.

[0070] If it is determined in S310 that flicker detection scanning is possible, it is determined in S311 whether the frame rate of the live view display is less than 120 fps. If it is determined that it is 120 fps or more, in S314 Above The second driving is started in which the above-mentioned flicker detection scanning is performed at a third interval, and flicker detection is performed using both the flicker detection image and the moving image.

[0071] If the frame rate is less than 120 fps, the power state is determined in S312. As in the case of still image live view display, if power is being supplied from an external source or if there is sufficient battery power remaining, the process proceeds to S313, where the second drive is started to perform the above-mentioned flicker detection scan at a first interval or a second interval, and flicker detection is performed using only the flicker detection image. If power is not being supplied from an external source but there is sufficient battery power remaining, the second drive is started in S314 to perform the above-mentioned flicker detection scan at a third interval, and flicker detection is performed using both the flicker detection image and the moving image. If power is not being supplied from an external source and there is not sufficient battery power remaining, the first drive is performed in S315, and flicker detection is performed using only the moving image.

[0072] While performing the flicker detection process, the process returns to S301 again to check the still image / moving image mode, and the flicker detection process continues.

[0073] <Other embodiments> In addition, the present invention includes a plurality of functions. Vessel? Even if applied to a system consisting of several devices, Place May be applied.

[0074] The present invention can also be realized by supplying a program for implementing one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0075] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0076] 100: camera body, 101: imaging element, 102: display unit, 103: CPU, 200: photographing lens, 201: lens group, 202: aperture, 203: CPU

Claims

1. an image sensor including a plurality of pixels, the plurality of pixels being divided into a plurality of regions including a first region and a second region, and capable of being driven under a shooting condition set for each of the regions; a control means for switching between a first drive for driving the first region and the second region under the same shooting conditions and a second drive for driving the first region and the second region under different shooting conditions; A detection means for detecting flicker based on a signal read out from the imaging element; the detection means has a determination means for determining whether or not flicker can be detected based on a signal read from the image sensor by the second driving, An electronic device characterized in that, when the determination means determines that flicker detection is possible based on the signal read out from the imaging element by the second drive, in the second drive, the control means controls to drive the second area under shooting conditions for detecting flicker, and the detection means detects flicker based on the detection signal read out from the second area.

2. The control means controls to perform the first drive when the determination means determines that flicker detection is not possible based on the signal read out from the image sensor by the second drive, The detection means detects flicker based on an image read from the image sensor when the first driving is performed.

2. The electronic device according to claim 1 .

3. The electronic device according to claim 2, characterized in that the determination means determines that flicker detection is not possible based on the signal read out from the imaging element by the second drive when the resolution of the image read out from the imaging element is higher than a predetermined threshold value.

4. 4. The electronic device according to claim 1, wherein, when flicker is detected and the period of the flicker is equal to or less than the frame rate of the image read from the image sensor, the control means sets the shooting conditions for the first area so that the charge accumulation time of the image sensor is an integer multiple of the period of the flicker.

5. a correction unit for correcting flicker in an image read from the imaging element, When a flicker is detected and a period of the flicker is longer than a frame rate of an image read from the imaging element, the detection means detects a change in luminance within an image or between images based on the image read from the imaging element in the first driving or the signal read from the first region in the second driving, 5. The electronic device according to claim 1, wherein the correction means applies a gain to the image that is set so as to correct the change in luminance.

6. The electronic device described in Claim 1, characterized in that the control means further switches between the first drive and the second drive depending on a power state.

7. The electronic device according to claim 6, characterized in that the determination means determines that flicker detection is not possible based on the signal read out from the imaging element by the second drive when the resolution of the image read out from the imaging element is higher than a predetermined threshold value.

8. The electronic device according to claim 6, characterized in that the determination means determines that flicker detection is not possible based on the signal read out from the imaging element by the second drive when a power saving priority setting that prioritizes saving power consumption is set.

9. The electronic device according to any one of claims 6 to 8, characterized in that, when performing the second driving, the control means drives the second area more frequently when the power state is a first state than when the power state is a second state lower than the first state.

10. The control means In a first power state in which power is supplied from an external source, the second driving is controlled so that the second region is driven at a first frequency; When power is not being supplied from an external source and the power state is a second power state that is greater than a predetermined first threshold, control is performed so that the second driving is performed at a second frequency that is lower than the first frequency, When power is not being supplied from an external source and the power state is a third power state that is equal to or lower than the first threshold and is higher than a second threshold that is lower than the first threshold, the second driving is controlled so that the driving of the second region is performed at a third frequency that is lower than the second frequency; When power is not being supplied from an external source and the power state is a fourth power state equal to or lower than the second threshold, the first driving is performed.

10. The electronic device according to claim 9.

11. The detection means includes: Detecting flicker based on the detection signal in the first power state and the second power state; In the third power state, detecting flicker based on the detection signal and the signal read from the first region; In the fourth power state, flicker is detected based on the signal obtained in the first driving.

11. The electronic device according to claim 10.

12. 12. The electronic device according to claim 1, wherein the control unit controls the image sensor by the first driving or the second driving during a period from when the electronic device is turned on until it becomes possible to capture an image.

13. 13. The electronic device according to claim 1, wherein the control means, when instructed to capture a still image, controls the image sensor by the first driving or the second driving before starting to capture the still image.

14. A method for controlling an electronic device having an image sensor including a plurality of pixels, the plurality of pixels being divided into a plurality of regions including a first region and a second region, the image sensor being capable of being driven under a shooting condition set for each of the regions, the method comprising the steps of: a control step in which a control unit switches between a first drive for driving the first region and the second region under the same shooting conditions and a second drive for driving the first region and the second region under different shooting conditions; a detection step in which a detection means detects flicker based on a signal read out from the image sensor; a determination step of determining whether or not flicker can be detected based on a signal read out from the image sensor by the second driving, A control method characterized in that, when it is determined in the determination step that flicker detection is possible based on the signal read out from the imaging element by the second driving, in the second driving, the control step controls to drive the second region under shooting conditions for detecting flicker, and in the detection step, flicker is detected based on the detection signal read out from the second region.

15. A program for causing a computer to function as each of the means other than the imaging element of the electronic device according to any one of claims 1 to 13.

16. A computer-readable storage medium storing the program according to claim 15.

Images