JP6997544B2 - Imaging device and its control method, program, storage medium - Google Patents

Description

The present invention relates to an image pickup apparatus capable of taking an image with reduced the influence of exposure unevenness due to flicker.

Generally, in an image pickup device such as a digital camera, when a subject is imaged in a state where a periodic change in the amount of light (so-called flicker) of an artificial light source occurs, the captured image is exposed or uneven in color due to the influence of flicker. May occur.

To solve this problem, for example, in Patent Document 1, an image not affected by flicker and an image affected by flicker are acquired, and the light intensity change cycle and peak position of flicker are detected based on the comparison result of the two images. The technology to do is proposed. Further, Patent Document 1 discloses that an image that is not affected by flicker is used for displaying a live view (hereinafter, simply referred to as LV) on a monitor.

On the other hand, in an image pickup device capable of reading out a specific area, a magnified image (so-called digitally zoomed image) can be acquired by setting the read-out area to a smaller area than the entire area constituting the image pickup element. (Enlarged image display). For example, Patent Document 2 proposes a method of performing high-resolution zooming by changing the reading range and the driving method of the image pickup device.

Japanese Unexamined Patent Publication No. 2015-888917 Japanese Unexamined Patent Publication No. 2002-314868

However, in the prior art disclosed in the above-mentioned patent document, the following problems occur when the light amount change cycle and the peak position of the flicker are detected while reading out a specific region.

For example, if the image magnified display as described above is performed in order to confirm the in-focus state on the subject during LV display, flicker is correctly detected when the flicker light source exists outside the area where the image signal is read out. It may not be possible. In this case, it is difficult to correctly reduce the influence of flicker.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image pickup apparatus capable of accurately reducing the influence of flicker even while enlarging an image of a specific area by a live view. That is.

The image pickup apparatus according to the present invention has an image pickup means for photographing a subject, a first display mode for displaying an image signal of a predetermined screen corresponding to the image pickup means on the display means, and the predetermined display mode corresponding to the image pickup means. Flicker detection that detects flicker of the illumination light of the subject by using the switching means for switching between the second display mode for displaying a part of the image signal on the screen on the display means and the image signal output from the image pickup means. Means, setting means for setting a flicker-reducing shooting mode for capturing an image of a subject and acquiring an image in which the influence of the flicker is reduced, and exposure control means capable of controlling the exposure time and exposure timing of the imaging means. The flicker detecting means is a first flicker that detects flicker using a part of the image signal in a state where the flicker reduction shooting mode is set and the second display mode is set. The detection is executed, and when the flicker is detected by the first flicker detection, the exposure control means controls so as to match the exposure timing of the image pickup means with the peak of the light amount change of the flicker. When flicker is not detected by the flicker detection of 1, it is characterized in that the exposure time of the image pickup means is controlled to be longer than the light amount change cycle of the flicker.

According to the present invention, it is possible to accurately reduce the influence of flicker even while enlarging an image in a specific area by live view.

The figure which shows the structure of the digital single-lens reflex camera system which is 1st Embodiment of the image pickup apparatus of this invention. The figure which shows the read area in LV and the display state. The figure which shows the processing example of the flicker detection of the first method. The flowchart which shows the operation of the flicker detection of the first method. The figure which shows the processing example of the flicker detection of the 2nd method. A flowchart showing the operation of the second method of flicker detection. The figure which shows the shutter control for flickerless shooting. A flowchart showing the operation of flickerless shooting. The flowchart of the flickerless shooting operation during LV expansion in 1st Embodiment. The flowchart of the flickerless shooting operation during LV expansion in the 2nd Embodiment. The flowchart of the flickerless shooting operation during LV expansion in the 3rd Embodiment. The flowchart of the flickerless shooting operation during LV expansion in 4th Embodiment. The flowchart of the flickerless shooting operation during LV expansion in the 5th Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First Embodiment)
FIG. 1 is a diagram showing a configuration of a digital single-lens reflex camera system according to a first embodiment of the image pickup apparatus of the present invention.

In FIG. 1, a digital single-lens reflex camera system includes a camera body 101 and a photographing lens 102 interchangeably attached to the camera body 101. The camera body 101 and the photographing lens 102 are mechanically and electrically connected to each other. The photographing lens 102 has a focusing lens 103 and an aperture 104, and is controlled from the camera body 101 via the lens mount contact group 105.

The main mirror 106 is a half mirror, and a sub mirror 107 is arranged on the back surface. In the state where the mirror is not raised as shown in FIG. 1, a part of the light flux from the photographing lens 102 is reflected by the main mirror 106 and incident on the upper finder screen 109. A part of the light flux transmitted without being reflected by the main mirror 106 is reflected by the sub mirror 107 and incident on the lower AF device (autofocus device) 108. The AF device 108 includes a phase difference detection type focus detection sensor. The focus detection sensor converts the light collected by the photographing lens 102 and incident through the submirror 107 into an electric signal, and outputs an image signal in each focus detection region.

The luminous flux reflected by the main mirror 106 is formed on the finder screen 109 to form a subject image. The subject image formed on the finder screen 109 is guided to the photographer's eyes through the pentaprism 111 and the eyepiece 110, and is visually recognized by the photographer. Further, the subject image formed on the finder screen 109 is guided to the AE device (automatic exposure device) 112 via the pentaprism 111.

The AE device 112 has a photometric sensor and converts an optical viewfinder image into a photometric image. Further, the AE device performs an automatic exposure calculation based on the photometric images continuously read from the photometric sensor and outputs the automatic exposure calculation to the CPU 116. The CPU 116 controls the opening amount of the aperture 104 of the photographing lens 102 based on the output result of the automatic exposure calculation, and adjusts the amount of light incident through the photographing lens 102. Further, the CPU 116 uses the photometric image generated by the photometric sensor to perform photometric calculation, subject tracking, flicker detection calculation, and the like. The camera body 101 is provided with a non-volatile memory 117 such as a ROM and a system memory 118 such as a RAM. Then, a program or the like stored in the non-volatile memory 117 is expanded in the system memory 118, and the CPU 116 controls the entire camera system by executing the expanded program. The system memory 118 is also used as a work area for the CPU 116. Further, a recording medium 119 such as a memory card is detachably arranged on the camera body 101, and captured image data and the like are recorded.

The image pickup element 113 includes a CMOS image sensor, a CCD image sensor, or the like in which a plurality of pixels having a photoelectric conversion element are arranged. When shooting, the main mirror 106 and the sub mirror 107 are moved from the shooting optical path, and the focal plane shutter 114 is opened to expose the image sensor 113 and image the subject image. The image pickup element 113 converts the light incident through the photographing lens 102 during exposure into an electric signal at each pixel, further performs A / D conversion to form image data, and outputs the image data to the CPU 116. The CPU 116 performs predetermined image processing or the like on the image data output from the image pickup element 113, and displays the image data on the monitor 115 or the like. Further, the image data is used for metering calculation, subject tracking, and flicker detection calculation, which is a characteristic operation of the present embodiment.

In the case of normal LV display (live view display), the signals from all the pixels arranged on the image pickup surface of the image pickup element 113 are not image-processed and displayed on the monitor 115. In order to display the entire surface at a fixed frame rate, pixel signals are added or thinned out based on the signal reading speed from each pixel of the image sensor 113, the processing speed of the CPU 116, the display rate of the monitor 115, etc., and relatively Display low resolution images.

The monitor 115 displays not only the captured image but also a GUI for making various settings and controls of the camera system. In the present embodiment, the enlargement setting / enlargement release button for confirming the focus is displayed, and the enlargement display and the enlargement display cancellation are performed by the operation from the user. When performing enlarged LV display (enlarged live view display), a specific area to be enlarged is to be expanded based on the signal reading speed corresponding to each pixel of the image sensor 113, the processing speed of the CPU 116, the display rate of the monitor 115, and the like. Only the signals of some pixels arranged in are read out. Then, image processing is performed on the read pixel data, and a partial but high-resolution image is displayed. Further, the GUI of the monitor 115 also displays a button for the user to select and switch between a normal shooting mode and a flicker reduction mode for shooting in which the flicker of the light source is reduced.

Here, the influence of the flicker of the light source (illumination light) in the camera system of the present embodiment will be described.

As described above, in general, in an image pickup device such as a digital camera, when a subject is imaged in a state where a periodic change in the amount of light of an artificial light source (so-called flicker) occurs, the effect of the flicker on the captured image. Exposure and color unevenness may occur due to. In such a case, an imaging device that detects flicker and adjusts the imaging timing or shutter speed so as not to be affected by the flicker has been conventionally proposed.

However, as in the present embodiment, in a camera system capable of magnifying and displaying an image in order to confirm the in-focus state of the subject during LV (live view) display, the flicker is correctly corrected during the magnified display. It may not be detected. That is, if the flicker light source exists outside the specific area from which the image signal is read, the influence of the flicker may not appear in the specific area, and the flicker cannot be detected correctly. If flicker cannot be detected correctly during the enlarged display in the LV operation, exposure unevenness due to the influence of flicker occurs in the image during the subsequent still image shooting accompanied by full-page readout.

This issue will be described in more detail. FIG. 2 is a diagram showing a read area in LV and a display image thereof. It is assumed that the region A-1 affected by the flicker light source and the region A-2 not affected by the flicker light source exist in the entire region A. The area B represents a read area and a display image thereof when a certain area of the area A-1 is enlarged and displayed. The area C represents a read area and a display image thereof when a certain area of the area A-2 is enlarged and displayed. Flicker detection is possible because the read area has light and darkness due to the influence of the flicker light source during the enlarged display of the area B. However, during the enlarged display of the area C, since there is no light and darkness due to the flicker light source in the read area, the flicker light source existing in the area B cannot be detected. That is, when the entire area A is photographed by the release operation during the enlarged display of the area C, the camera determines that there is no influence of the flicker, so that the flickerless photography for reducing the influence of the flicker light source is not performed.

In the camera system of the present embodiment, the user can switch between a normal shooting mode and a flicker-reduced shooting mode for shooting in which the flicker of the light source is reduced. Then, when the user selects the flicker-reduced shooting mode, the camera body 101 performs an operation peculiar to the present embodiment as described in detail later.

Next, although the first and second types of flicker detection are performed in the present embodiment, the flicker detection of the first method in the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing an example of shutter drive and flicker detection processing in the flicker detection of the first method in the present embodiment. FIG. 4 is a flowchart showing the operation of the flicker detection of the first method during the LV display (including the normal display (first display mode) and the enlarged display (second display mode)) in the present embodiment. Is. Here, a case where 100 Hz flicker is generated will be described as an example. The operation shown in the flowchart of FIG. 4 is performed by the CPU 116 executing a program stored in the non-volatile memory 117.

First, in step S401, the CPU 116 controls the image pickup device 113 to perform the first storage, and acquires an image (FIG. 3: image A). At this time, by controlling the accumulation time to be 10 ms, which is the same as the flicker cycle, an image that is not affected by the flicker is acquired. The acquired image is used for displaying the monitor 115 in the next step S402.

Subsequently, in step S403, the CPU 116 controls the image sensor 113 to perform the second storage and acquire an image (FIG. 3: image B). At this time, by controlling the accumulation time to be sufficiently shorter than the flicker cycle, for example, 1 ms, an image affected by the flicker is acquired.

In step S404, the CPU 116 generates an image B'from which the flicker component is extracted from the image B by calculating the ratio of the image A to the image B as shown in the lower part of FIG. The flicker waveform is obtained from the generated image B', and the peak timing of the intensity of the light source is calculated in step S405. At this time, if the peak timing is calculated for the first time, the determination in step S406 becomes NO, and the process returns to step S401. By executing steps S405 from step S401 again, the images C and D of FIG. 3 are acquired, and the image D'is generated from the ratio of the two images. Then, the flicker waveform is obtained from the generated image D', and the peak timing of the intensity of the light source is calculated. When the second peak timing calculation is completed, the determination in step S406 becomes YES, and the process proceeds to step S407.

In step S407, the CPU 116 determines the flicker cycle from the time difference between the two calculated peak timings and ends. The detailed algorithm / calculation method for flicker detection of the first method is disclosed in Patent Document 1 and the like, and since it is a known technique, detailed description thereof will be omitted here. Further, in the flicker detection of the first method in the present embodiment, the in-plane of the acquired image is divided into a plurality of regions, and the flicker detection is performed based on the ratio of each region. As a result, flicker can be detected even when flicker occurs only in a part of the screen (left part in FIG. 3) as in the images E, F, and E'shown in the lower part of FIG. Is possible.

Next, the flicker detection of the second method in the present embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 is a diagram showing an example of shutter drive and flicker detection processing in the flicker detection of the second method in the present embodiment. FIG. 6 is a flowchart showing the operation of the flicker detection of the second method in the present embodiment. The operation shown in the flowchart of FIG. 6 is performed by the CPU 116 executing the program stored in the non-volatile memory 117.

First, in step S601, the CPU 116 controls the image sensor 113 to acquire images 12 times in succession at a predetermined frame rate. Here, the predetermined frame rate is about 600 Hz. That is, 6 images are acquired in 1 cycle of flicker 10 ms, and 12 images are acquired in 2 cycles. Subsequently, the integrated value of the brightness of the entire screen is obtained for each image acquired in step S602. Next, in step S603, the flicker cycle is determined from the transition of the integrated value obtained for each image. Next, in step S604, the peak timing of the flicker is calculated from the integrated value, and the process ends.

The detailed algorithm / calculation method for flicker detection of this second method is disclosed in Patent Document 1 and the like, and since it is a known technique, detailed description thereof will be omitted here. Further, in the second flicker detection in Patent Document 1, a plurality of images are acquired at a predetermined frame rate, and the flicker waveform is calculated from the change in the brightness of the entire screen. However, in the present embodiment, the in-plane of the acquired image is divided into a plurality of regions, and flicker detection is performed based on the change in brightness for each region. This makes it possible to detect flicker even when flicker occurs only in the lower part of the plane as shown in the lower part of FIG.

Next, exposure control for flickerless shooting in the camera system of the present embodiment will be described with reference to FIG. 7. FIG. 7 is a diagram showing shutter control for capturing an image that is not affected by flicker according to the flicker waveform. Here, a case where the flicker detection is completed before the shooting instruction is given by pressing the release switch (not shown) will be described. When flicker is detected by the flicker detection process, the peak timing of the flicker is detected, and the flicker tuning signal for synchronizing the peak of the flicker and the shooting timing is continuously output accordingly. If a shooting instruction is given by pressing the release switch during that time, the exposure is not performed as shown by the broken line S1 at the timing immediately after the shooting instruction shown by R in FIG. 7, but the flicker shown by the solid line S2 in FIG. The shutter is driven and exposure is performed at a timing that matches the output of the tuning signal F. As a result, the exposure timing is controlled according to the peak timing of the flicker each time shooting is performed, and it is possible to suppress the variation in exposure. In other words, shooting that is not affected by flicker can be realized.

Here, a case where flicker is detected before the release switch is pressed has been described. However, even when the flicker detection process is performed after the release switch is pressed, a tuning signal is output after the flicker is detected, and the shutter and exposure are controlled according to the signal.

Next, the flickerless shooting in the present embodiment will be described with reference to the flowchart of FIG. The operation shown in the flowchart of FIG. 8 is performed by the CPU 116 executing the program stored in the non-volatile memory 117.

First, in step S801, the CPU 116 performs the first method of flicker detection. The flicker detection of the first method is as already described with reference to FIGS. 3 and 4. Next, in step S802, the CPU 116 uses the GUI of the monitor 115 to determine whether or not the LV enlarged display for confirming the focus is set. If it is determined that the LV enlarged display is not set, the process proceeds to step S809.

In step S809, the CPU 116 determines whether or not the release switch (not shown) is pressed, and if it is determined that the release switch is not pressed, the process returns to step S801 and repeats the processes after step S801. If it is determined that the button has been pressed, the process proceeds to step S810. In step S810, the CPU 116 determines whether or not the result of the flicker detection of the first method is under the flicker light source. If it is determined that the light source is under the flicker light source, the process proceeds to step S811. In step S811, the flickerless shooting process is performed based on the result of the flicker detection of the first method, and the process ends. This flickerless shooting process has already been described with reference to FIG. 7.

If it is determined in step S810 that the flicker is not under the flicker light source by the flicker detection of the first method, the process proceeds to step S812. In step S812, since there is no influence of flicker, normal shadow processing is performed and the process ends.

On the other hand, if it is determined in step S802 that the LV enlarged display is set, the process proceeds to step S803. In step S803, the CPU 116 performs a storage process of flicker information before LV expansion. In the flicker information storage process before the LV expansion, the process of storing the information of the result of the flicker detection of the first method performed in step S801 in the storage area in the CPU 116 is performed.

Next, in step S804, the CPU 116 performs the flicker detection of the first method in the LV expanded state. In the flicker detection of the first method during the LV enlargement, the flicker detection of the first method described with reference to FIGS. Flicker detection is performed. As described above, in the flicker detection of the first method during LV expansion, even if there is actually flicker, there may be no light or darkness due to the flicker light source in the read specific area, and the flicker light source is correctly detected as the entire screen. May not be possible.

Next, in step S805, the CPU 116 determines whether or not the release switch (not shown) is pressed, and if it is determined that the release switch is not pressed, the process proceeds to step S808. In step S808, the CPU 116 uses the GUI of the monitor 115 to determine whether or not the release of the LV enlarged display for confirming the focus is set. If it is determined that the cancellation of the LV enlarged display is set, the processing after step S801 is repeated, and if it is determined that the cancellation of the LV enlarged display is not set, the processing after step S804 is repeated.

On the other hand, if it is determined in step S805 that the release switch has been pressed, the process proceeds to step S806. In step S806, the CPU 116 performs a storage process of flicker information during LV expansion. In the flicker information storage process during LV expansion, the process of storing the result information of the flicker detection of the first method during LV expansion performed in step S804 in the storage area in the CPU 116 is performed.

Next, in step S807, the CPU 116 performs flickerless shooting during LV expansion and ends. The above is the procedure of the operation of flickerless shooting in this embodiment.

Next, FIG. 9 is a flowchart showing the operation of flickerless shooting during LV enlargement in step S807 of FIG.

First, in step S901, the CPU 116 sets the shutter speed to a time that is always longer than the flicker cycle. Specifically, by setting the exposure time to be longer than 1/50 (seconds), the shutter speed is set to be unaffected by either the 60 Hz flicker light source or the 50 Hz flicker light source. By doing so, even if the peak timing of the flicker cannot be detected, it is possible to take an image that is not affected by the flicker.

Next, in step S902, the CPU 116 opens the focal plane shutter 114 to execute a shooting process for exposing the image pickup device 113 at the shutter speed set in step S901, and ends.

As described above, according to the first embodiment, it is possible to accurately reduce the influence of flicker even while enlarging the image of a specific area by the live view. Further, since the flicker detection process is not performed again during the LV expansion, the time lag until the actual shooting when the release switch is pressed can be reduced.

(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described. In this second embodiment, the configuration and operation of the digital single-lens reflex camera system are substantially the same as those in the first embodiment, and only the operation of flickerless imaging during LV enlargement in step S807 of FIG. 8 is different. Therefore, the description of the common parts with the first embodiment will be omitted, and only the different parts will be described.

FIG. 10 is a flowchart showing the operation of flickerless shooting during LV expansion in the second embodiment.

First, in step S1001, the CPU 116 acquires the LV expanding flicker information stored in step S806 of the flowchart of FIG. 8 from the storage area. Next, in step S1002, it is determined from the acquired flicker light source information during LV expansion whether or not there is a flicker light source during LV expansion. If it is determined that there is a flicker light source, the process proceeds to step S1003. In step S1003, based on the flicker light source information during LV expansion, the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1002 that there was no flicker light source during LV expansion, the process proceeds to step S1004. In this case, as already described with reference to FIG. 2, even if flicker is not detected in the enlarged region, it is not determined that there is no flicker light source. Further, since the flicker is not detected in step S1001, even if the flicker actually occurs, the peak timing is unknown. That is, here, the flickerless shooting described with reference to FIG. 7 cannot be performed. Therefore, in step S1004, the CPU 116 sets the shutter speed to a time that is always longer than the flicker cycle. Specifically, by setting the exposure time to be longer than 1/50 (seconds), the shutter speed is set to be unaffected by either the 60 Hz flicker light source or the 50 Hz flicker light source.

Next, in step S1005, the CPU 116 executes a shooting process of exposing the image pickup element 113 at the exposure time set in step S1004 by opening the focal plane shutter 114, and ends.

As described above, also in this second embodiment, it is possible to accurately reduce the influence of flicker even while enlarging the image of a specific area by the live view. Further, by using the information of the flicker detection process during the LV expansion in step S804 without performing the flicker detection process again during the LV expansion, the time lag until the actual shooting when the release switch is pressed is reduced. can do.

(Third embodiment)
Also in this third embodiment, the configuration and operation of the digital single-lens reflex camera system are substantially the same as those in the first embodiment, and only the operation of flickerless imaging during LV enlargement in step S807 of FIG. 8 is different. Therefore, the description of the common parts with the first and second embodiments will be omitted, and only the different parts will be described.

FIG. 11 is a flowchart showing the operation of flickerless shooting during LV expansion in the third embodiment.

First, in step S1101, the CPU 116 acquires the LV expanding flicker information stored in step S806 of the flowchart of FIG. 8 from the storage area. Next, in step S1102, it is determined from the acquired flicker light source information during LV expansion whether or not there is a flicker light source during LV expansion. If it is determined that there is a flicker light source, the process proceeds to step S1103. In step S1103, based on the flicker light source information during LV expansion, the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1102 that there was no flicker light source during LV expansion, the process proceeds to step S1104. In this case, as already described with reference to FIG. 2, even if flicker is not detected in the enlarged region, it is not determined that there is no flicker light source. Therefore, in step S1104, the CPU 116 ends the LV enlarged display and switches to the full screen display, and performs the flicker detection of the second method described with reference to FIGS. 5 and 6. This is a process of confirming the presence or absence of flicker using the entire area again even if it is determined that there is no flicker during LV expansion. Here, the flicker detection of the second method does not involve the display operation as in the flicker detection of the first method. Also, instead of determining the flicker waveform, the flicker is determined based on the transition of brightness. Therefore, the number and time of processing until the flicker determination can be shortened, the accurate determination can be made, and the flicker detection time can be shortened.

In step S1105, the CPU 116 determines whether or not there is a flicker light source from the result of the flicker detection of the second method in step S1104. If it is determined that there is a flicker light source, the process proceeds to step S1106. In step S1106, based on the flicker light source information obtained by the flicker detection of the second method, the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1105 that there is no flicker light source, the process proceeds to step S1107. In step S1107, since flicker was not detected in the flicker detection for the entire screen in step S1104, it is determined that there is no influence of flicker, and normal shooting processing is performed to end the process.

As described above, also in this third embodiment, it is possible to accurately reduce the influence of flicker even while enlarging the image of a specific area by the live view. Further, by using the information of the flicker detection process during LV expansion in step S804 or by performing the flicker detection of the second method, an image that is not affected by the flicker is taken without slowing down the shutter speed. Is possible.

(Fourth Embodiment)
Also in this fourth embodiment, the configuration and operation of the digital single-lens reflex camera system are substantially the same as those in the first embodiment, and only the operation of flickerless imaging during LV enlargement in step S807 of FIG. 8 is different. Therefore, the description of the parts common to the first to third embodiments will be omitted, and only the different parts will be described.

FIG. 12 is a flowchart showing the operation of flickerless shooting during LV expansion in the fourth embodiment.

First, in step S1201, the CPU 116 acquires the LV expanding flicker information stored in step S806 of the flowchart of FIG. 8 from the storage area. Next, in step S1202, it is determined from the acquired flicker light source information during LV expansion whether or not there is a flicker light source during LV expansion. If it is determined that there is a flicker light source, the process proceeds to step S1203. In step S1203, based on the flicker light source information during LV expansion, the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1202 that there was no flicker light source during LV expansion, the process proceeds to step S1204. In step S1204, the flicker information before LV expansion stored in step S803 of the flowchart of FIG. 8 is acquired from the storage area. Next, in step S1205, it is determined from the acquired flicker light source information before LV expansion whether or not there is a flicker light source before LV expansion. If it is determined that there is a flicker light source, the process proceeds to step S1203, and the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7 based on the flicker light source information before LV enlargement. ..

On the other hand, if it is determined in step S1205 that there was no flicker light source before the LV expansion, the process proceeds to step S1206. In step S1206, the CPU 116 sets the shutter speed to a time that is always longer than the flicker cycle. Specifically, by setting the exposure time longer than 1/50 (seconds), the shutter speed is set to be unaffected by either the 60 Hz flicker light source or the 50 Hz flicker light source.

Next, in step S1207, the CPU 116 executes a shooting process for exposing the image pickup element 113 at the exposure time set in step S901 by opening the focal plane shutter 114, and ends the process.

In the flickerless shooting during LV enlargement in the fourth embodiment, it is possible to shoot an image that is not affected by flicker even for a subject that is partially affected by the flicker light source.

As described above, also in the fourth embodiment, it is possible to accurately reduce the influence of flicker even while enlarging the image of a specific area by the live view. Further, the flicker detection process during the LV expansion is not performed again during the LV expansion, and the information of the flicker detection process during the LV expansion in step S804 or the information of the flicker detection process before the LV expansion in step S801 is used to release the flicker. It is possible to reduce the time lag until the actual shooting when the switch is pressed.

(Fifth Embodiment)
Also in this fifth embodiment, the configuration and operation of the digital single-lens reflex camera system are substantially the same as those in the first embodiment, and only the operation of flickerless imaging during LV enlargement in step S807 of FIG. 8 is different. Therefore, the description of the parts common to the first to fourth embodiments will be omitted, and only the different parts will be described.

FIG. 13 is a flowchart showing the operation of flickerless shooting during LV expansion in the fifth embodiment.

First, in step S1301, the CPU 116 acquires the LV expanding flicker information stored in step S806 of the flowchart of FIG. 8 from the storage area. Next, in step S1302, it is determined from the acquired flicker light source information during LV expansion whether or not there is a flicker light source during LV expansion. If it is determined that there is a flicker light source, the process proceeds to step S1303. In step S1303, based on the flicker light source information during LV expansion, the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1302 that there was no flicker light source during LV expansion, the process proceeds to step S1304. In step S1304, the flicker information before LV expansion stored in step S803 of the flowchart of FIG. 8 is acquired from the storage area. Next, in step S1305, it is determined from the acquired flicker light source information before LV expansion whether or not there is a flicker light source before LV expansion. If it is determined that there is a flicker light source, the process proceeds to step S1303, and based on the flicker light source information before the LV enlargement, the flickerless shooting process is performed and ends according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1305 that there was no flicker light source before the LV expansion, the process proceeds to step S1306. In this case, as already described with reference to FIG. 2, even if flicker is not detected in the enlarged region, it is not determined that there is no flicker light source. Therefore, in step S1306, the CPU 116 ends the LV enlarged display and switches to the full screen display, and performs the flicker detection of the second method described with reference to FIGS. 5 and 6. This is a process of confirming the presence or absence of flicker using the entire area again even if it is determined that there is no flicker during LV expansion. Here, the flicker detection of the second method does not involve the display operation as in the flicker detection of the first method. Also, instead of determining the flicker waveform, the flicker is determined based on the transition of brightness. Therefore, the number and time of processing until the flicker determination can be shortened, the accurate determination can be made, and the flicker detection time can be shortened.

In step S1307, the CPU 116 determines whether or not there is a flicker light source from the result of the flicker detection of the second method in step S1306. If it is determined that there is a flicker light source, the process proceeds to step S1308. In step S1308, based on the flicker light source information obtained by the flicker detection of the second method, the flickerless shooting process is performed and terminated according to the flickerless shooting operation already described with reference to FIG. 7.

On the other hand, if it is determined in step S1307 that there is no flicker light source, the process proceeds to step S1309. In step S1309, since flicker was not detected in the flicker detection for the entire screen in step S1306, it is determined that there is no influence of flicker, and normal shooting processing is performed to end the process.

As described above, also in the fifth embodiment, it is possible to accurately reduce the influence of flicker even while enlarging the image of a specific area by the live view. Further, the shutter speed is increased by using the information of the flicker detection process during LV expansion in step S804, the information of the flicker detection process before LV expansion in step S801, or by performing the flicker detection of the second method. It is possible to shoot an image that is not affected by flicker without delaying.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

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

101: Camera body, 102: Shooting lens, 103: Focusing lens, 104: Aperture, 105: Lens mount contact group, 106: Main mirror, 107: Sub mirror, 108: AF device, 112: AE device, 113: Image sensor, 114: Focal plane shutter, 115: Monitor

Claims (11)

An imaging means that captures the subject,
A first display mode for displaying an image signal of a predetermined screen corresponding to the image pickup means on the display means, and a second display mode for displaying a part of the image signal of the predetermined screen corresponding to the image pickup means on the display means. Switching means to switch between display modes and
A flicker detecting means for detecting the flicker of the illumination light of the subject by using the image signal output from the imaging means, and the flicker detecting means.
A setting means for setting a flicker reduction shooting mode for capturing an image of a subject and acquiring an image in which the influence of the flicker is reduced, and
An exposure control means capable of controlling the exposure time and exposure timing of the image pickup means is provided.
The flicker detecting means executes a first flicker detection that detects flicker by using a part of the image signals in a state where the flicker reduction shooting mode is set and the second display mode is set. ,
When the flicker is detected by the first flicker detection, the exposure control means controls so as to match the exposure timing of the imaging means with the peak of the light amount change of the flicker, and the first flicker detection causes the exposure control means to adjust the exposure timing of the image pickup means. When flicker is not detected, the image pickup apparatus is characterized in that the exposure time of the image pickup means is controlled to be longer than the light amount change cycle of the flicker. The image pickup apparatus according to claim 1, wherein in the first display mode, the image pickup means outputs a predetermined pixel by thinning out a predetermined pixel from the pixel of the predetermined screen corresponding to the image pickup means. The image pickup apparatus according to claim 1 or 2, wherein in the second display mode, the image pickup means outputs a part of the image signals without thinning out. The image pickup apparatus according to any one of claims 1 to 3, wherein in the second display mode, a part of the image signal is enlarged and displayed on the display means. The flicker detecting means detects flicker based on an image signal in a region wider than the image signal of the part of the predetermined screen in a state where the first display mode is set. The image pickup apparatus according to any one of claims 1 to 4, wherein the flicker detection is performed. When the flicker reduction shooting mode is set, the flicker detecting means executes the first flicker detection after switching from the first display mode to the second display mode by the switching means. The image pickup apparatus according to claim 5. When the flicker is not detected by the first flicker detection, the exposure control means refers to the result of the second flicker detection executed before switching to the second display mode, and refers to the second flicker detection. If flicker is detected by the detection, the exposure timing of the image pickup means is controlled to match the peak of the light amount change of the flicker, and if the flicker is not detected by the second flicker detection, the flicker The image pickup apparatus according to claim 6, wherein the exposure time of the image pickup means is controlled to be longer than the light amount change cycle. The flicker detecting means is characterized in that the flicker is detected by dividing an image taken with an exposure time shorter than the flicker cycle by an image taken with the same exposure time as the flicker cycle. Item 6. The image pickup apparatus according to any one of Items 1 to 7 . It is a control method of an image pickup device provided with an image pickup means for photographing a subject.
A first display mode for displaying an image signal of a predetermined screen corresponding to the image pickup means on the display means, and a second display mode for displaying a part of the image signal of the predetermined screen corresponding to the image pickup means on the display means. Switching process to switch between display mode and
A flicker detection step of detecting flicker of the illumination light of the subject using an image signal output from the image pickup means, and a flicker detection step.
A setting process for setting a flicker reduction shooting mode for capturing an image of a subject and acquiring an image in which the influence of the flicker is reduced, and
It has an exposure control step of controlling the exposure time and the exposure timing of the image pickup means.
In the flicker detection step, in a state where the flicker reduction shooting mode is set and the second display mode is set, the first flicker detection for detecting flicker using a part of the image signals is executed. ,
In the exposure control step, when flicker is detected by the first flicker detection, the exposure timing of the imaging means is controlled to match the peak of the light amount change of the flicker, and the first flicker detection is used. A control method for an image pickup apparatus, characterized in that when flicker is not detected, the exposure time of the image pickup means is controlled to be longer than the light amount change cycle of the flicker. A program for causing a computer to execute each step of the control method according to claim 9 . A computer-readable storage medium that stores a program for causing a computer to execute each step of the control method according to claim 9 .

Images