JP6789672B2 - Imaging device, its control method and program - Google Patents

Description

The present invention relates to an imaging device that performs intermittent imaging, and a control method and program thereof.

Conventionally, a technique for intermittently imaging a subject (so-called interval shooting) has been known. According to Patent Document 1, when a plurality of images are acquired by intermittently performing imaging at preset shooting intervals, the subject light is metered immediately before each imaging, and the photometric value is obtained. A technique for performing automatic exposure photography using an automatically calculated exposure value has been proposed.

JP-A-2015-139029

In the technique described in Patent Document 1, since the exposure is automatically changed according to the change of the subject light for each of a plurality of images taken, the brightness of the entire image of each image is the subject light in the acquired plurality of images. The brightness will change according to the change. However, in such a state, by adjusting the brightness of the entire image of the plurality of images according to the change in the subject light, the brightness of the subject in the image varies among the plurality of images. It ends up.

Here, in the case of acquiring a moving image (so-called time-lapse moving image) by joining a plurality of intermittent images acquired by using the technique described in Patent Document 1, it is caused by the variation in the brightness of the subject among the plurality of images. As a result, the quality of time-lapse movies deteriorates.

An object of the present invention is to prevent deterioration of the quality of a moving image obtained by joining a plurality of images acquired by performing intermittent imaging.

The imaging device of the present invention that achieves the above object is an imaging device that performs intermittent imaging in order to acquire a moving image in which a plurality of images are joined, and is an imaging means for capturing a subject and the imaging means. The brightness value acquisition means for acquiring the brightness value of the subject to be imaged, the exposure control means for controlling the exposure according to the brightness value acquired by the brightness value acquisition means, and the brightness value acquisition means in the exposure control means. It has a range setting means for setting a non-exposure tracking range that does not change the exposure according to a change in the acquired brightness value, and the range setting means is based on information on the time for performing intermittent imaging. , The non-exposure tracking range is set.

According to the present invention, it is possible to suppress the deterioration of the quality of a moving image obtained by joining a plurality of acquired images by performing intermittent imaging.

It is a block diagram which shows the structural example of the digital camera 100 which is the embodiment of the image pickup apparatus which carried out this invention. It is an external view of the digital camera 100 which is the embodiment of the image pickup apparatus which carried out this invention. It is a flowchart explaining the imaging process which concerns on embodiment of this invention. It is a figure which illustrates the change of the luminance value at the time of performing an intermittent image pickup. It is a figure which illustrates the change of the brightness between images acquired when the non-exposure tracking range ΔBvTH is set and intermittent imaging is performed. It is a figure exemplifying the change of the brightness value and the change of the brightness of a plurality of images when the imaging time interval is 1 hour in the time-lapse moving image mode. It is a figure which exemplify the change of the brightness of a plurality of images acquired by the imaging process which concerns on embodiment of this invention.

(Embodiment)
(Basic configuration of digital camera 100)
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration example of a digital camera (hereinafter, simply referred to as a camera) 100 which is an embodiment of an imaging device according to the present invention. One or more of the functional blocks shown in FIG. 1 may be realized by hardware such as an ASIC or a programmable logic array (PLA), or may be realized by a programmable processor such as a CPU or MPU executing software. You may. It may also be realized by a combination of software and hardware. Therefore, in the following description, the same hardware can be realized as the main body even if different functional blocks are described as the main body of operation.

As shown in FIG. 1, the image pickup lens group 101 is an optical member including a focus lens, a zoom lens, a shift lens, and the like. The diaphragm 102 is a light amount adjusting member that adjusts the light amount of the light flux of the subject passing through the image pickup lens group 101. The sensor 103 is a charge storage type solid-state image sensor such as a CCD or CMOS, and is an image pickup means that generates analog image data by photoelectric conversion (imaging) of the luminous flux of a subject incident on the image sensor group 101. .. The A / D conversion unit 104 is a conversion means for converting the analog image data output from the sensor 103 into digital image data. The image processing unit 105 is an image processing means that performs various processes such as WB adjustment processing and gradation processing on the digital image data output from the A / D conversion unit 104.

The memory 106 is a storage means that can be electrically erased and stored, such as an EEPROM represented by a flash memory, and can record data related to the operation of the camera 100 and various data acquired by the camera 100. In the memory 106, constants for operations executed by the camera 100, various exposure conditions, calculation formulas, and the like are recorded in advance. The encoder unit 107 is a conversion means for converting digital image data into a recording format. The recording control unit 108 is a control means for controlling the recording of image data in the camera 100, and controls the conversion of digital image data in the encoder unit 107 based on a preset recording format. The display unit 109 is a display means composed of a TFT type LCD (thin film transistor drive type liquid crystal display) or the like for displaying the acquired image data, and the digital image data is converted by the D / A conversion unit (not shown). It can display analog image data for display.

The camera control unit 110 is a control means that comprehensively controls the operation of the camera 100. The camera control unit 110 is also a luminance value acquisition means for acquiring the luminance value of the image data based on the acquired image data. Specifically, the camera control unit 110 divides the acquired image data into a plurality of blocks and calculates the average luminance value of the luminance values of each block. Then, the camera control unit 110 integrates the average luminance value of each block to acquire the representative luminance value. In the following description, this representative luminance value is simply referred to as the luminance value and used for various processes and controls such as exposure control. In the present embodiment, the brightness value is acquired based on the image data acquired by using the sensor 103, but the brightness value may be acquired by using a so-called photometric sensor other than the sensor 103.

The exposure control unit 111 is an exposure control means for controlling the exposure when acquiring image data using the sensor 103, and can control the exposure according to the brightness value acquired by the camera control unit 110. In the present embodiment, as exposure, the exposure control unit 111 controls the aperture value related to the opening degree of the aperture 113, the shutter speed related to the charge accumulation time of the sensor 103, the shooting sensitivity related to the analog and digital gain amounts, and the like. Information (table data, etc.) regarding exposure (appropriate exposure) with respect to the luminance value is stored in the memory 106 in advance. The exposure control unit 111 can set an appropriate exposure according to the brightness value based on this information. The exposure control unit 111 is also a range setting means for setting the non-exposure tracking range ΔBvTH, which will be described later. This detail will be mentioned later in the description of the acquisition method of the time-lapse movie.

The lens driving unit 112 is a driving means that operates the image pickup lens group 101 in response to an instruction from the camera control unit 110. The aperture drive unit 113 is a drive means for driving the aperture 102 in response to an instruction from the exposure control unit 111. The operation unit 114 is an operation means capable of inputting operations related to each operation of the camera 100. FIG. 2 is an external view of the camera 100, which is an embodiment of the image pickup apparatus according to the present invention. As shown in FIG. 2, the operation unit 114 includes a release switch 114a capable of instructing an image pickup preparation operation of a subject and an instruction to start an image pickup operation, and an operation button 114b capable of inputting an operation related to each operation of the camera 100. ing. The display unit 109 may be configured to employ a so-called touch panel or the like that can be operated by the user, and the display unit 109 is also used as the operation unit 114.

The light emission control unit 115 determines the amount of light emitted by the light emitting unit 116 and the amount of light emitted from the light emitting unit 116 when taking an image of a subject (hereinafter referred to as light emission imaging) accompanied by the light emission of the light emitting unit 116 based on the light emission determination by the camera control unit 110. It is a control means for controlling light emission timing and the like. The external I / F 117 is a connection means for controlling the connection between the camera 100 and an external device (not shown) or an external memory (not shown) provided outside the camera 100. The above is the basic configuration of the camera 100 of the present embodiment.

(Imaging operation)
Hereinafter, the image capturing operation of the subject using the camera 100 will be described. First, the camera control unit 110 detects that the release switch 114a has been operated while power is being supplied to each unit of the camera 100, and starts an imaging operation of the subject. In the imaging operation, first, a shutter (not shown) provided between the imaging lens group 101 and the sensor 103 is retracted from the optical path, and the light flux incident through the imaging lens group 101 is imaged on the sensor 103. .. Next, in response to an instruction from the camera control unit 110, the exposure control unit 111 operates each unit of the camera 100 based on the information recorded in advance in the memory 106 to set the exposure for acquiring the brightness value. Then, the camera control unit 110 executes imaging, reads out the electric charge accumulated in the sensor 103, and outputs analog image data. The A / D conversion unit 104 performs sampling adjustment, gain adjustment, and A / D conversion on the analog image data output from the sensor 103, and outputs the digital image data. The image processing unit 105 performs various image processing on the digital image data output from the A / D conversion unit 104, and outputs the processed digital image data.

The camera control unit 110 acquires a luminance value (representative luminance value) based on the acquired (digital) image data. Then, the exposure control unit 111 executes exposure control and sets an appropriate exposure for the acquired luminance value. Further, the camera control unit 110 calculates the distance information (subject distance) from the camera 100 to the subject based on the acquired image data. Then, the camera control unit 110 sets the lens position of the focus lens of the image pickup lens group 101 to be in focus on the subject based on the calculated subject distance (AF (AutoForcus) control). In the present embodiment, the image processing unit 105 acquires an evaluation value for focus detection (hereinafter, referred to as a contrast evaluation value) based on the contrast information of the image data acquired while shifting the lens position of the focus lens. Then, the camera control unit 110 calculates the subject distance based on the acquired contrast evaluation value. The method of calculating the subject distance is not limited to this. For example, a sensor for AF control may be provided separately, or pixels for detecting the phase difference may be provided in a plurality of pixels constituting the sensor 103, and the subject distance may be calculated by a so-called phase difference detection method. The above is the image pickup preparation operation of the camera 100.

When the image pickup preparation operation of the camera 100 is completed, the camera control unit 110 executes imaging at the previously set exposure and the lens position of the focus lens to acquire analog image data. Since the operation up to the image processing by the image processing unit 105 is as described above, the description thereof will be omitted. The digital image data subjected to various image processing is converted into a recording format by the recording control unit 108 via the encoder unit 107 and recorded in the memory 106. Further, the camera control unit 110 converts the digital image data into analog image data for display by the D / A conversion unit (not shown), and then displays the image data on the display unit 109. The above is the basic imaging operation of the camera 100. In the above description, a series of operations from preparation for imaging to recording and display of image data are continuously performed according to the operation of the release switch 114a by the user, but the present invention is not limited to this. Absent. For example, the imaging preparation operation is executed according to the SW1 state (for example, half-pressed) of the release switch 114a, and the actual imaging operation is executed according to the SW2 state (for example, fully pressed) of the release switch 114a. It may be.

(How to get time-lapse video)
The camera 100 of the present embodiment can set a plurality of modes such as a normal moving image mode and a time-lapse moving image mode as an imaging mode for acquiring a moving image. The normal moving image mode is an imaging mode in which a plurality of image data acquired by executing charge accumulation (imaging) a plurality of times per second using the sensor 103 are sequentially connected and displayed. On the other hand, the time-lapse movie mode is a mode in which a plurality of images acquired by performing charge accumulation (imaging) at intervals of at least about 1 second or more using the sensor 103 are sequentially connected and displayed. is there. The moving image acquired by this configuration is a moving image compressed with temporal changes (hereinafter referred to as a time-lapse moving image), and the (playback) time of the moving image is relative to the total imaging time for acquiring one time-lapse moving image. short. Each imaging mode can be set by the user operating the operation button 114b. Hereinafter, the operation of the camera 100 when the time-lapse moving image mode is set will be described.

In the time-lapse movie mode, the camera 100 may perform intermittent imaging based on the imaging time interval and the total number of imaging times (or the total imaging time, etc.) preset by the user in response to the user's imaging start instruction. it can. By executing this continuous imaging, the camera 100 can acquire a plurality of temporally continuous image data (hereinafter, simply referred to as an image) used for acquiring a moving image in which a plurality of images are joined. Then, the camera control unit 110 can connect the plurality of images to each other and acquire a time-lapse moving image which is a moving image compressed with temporal changes. The above-mentioned imaging time interval is a time interval for executing continuous imaging in intermittent imaging related to the generation of one time-lapse moving image. In other words, the above-mentioned imaging time interval is a time interval for executing continuous imaging for acquiring a plurality of images (still images) used for generating one time-lapse moving image. In the present embodiment, the imaging time interval is preset to 1 second, 30 seconds, 1 minute, 15 minutes, 30 minutes, 1 hour, 3 hours, 5 hours, 10 hours, and 24 hours. The user can set any time interval. The imaging time interval that can be set is not limited to this, and for example, an arbitrary time interval may be freely set by the user. Further, the total number of imagings described above is an intermittent number of imagings for acquiring a plurality of images used for generating one time-lapse moving image. Therefore, the total number of images captured matches the total number of multiple images used to generate one time-lapse movie. The camera 100 of the present embodiment can set the total number of imaging times from 2 times to infinity (for example, until the power is turned off).

The imaging time interval and the total number of imagings can be set by the user operating the operation button 114b, and the information regarding the set imaging time interval and the total number of imagings is recorded in the memory 106. The camera control unit 110 reads out information on the imaging time interval and the total number of imagings recorded in the memory 106, and executes intermittent imaging in the time-lapse moving image mode. Then, the camera control unit (moving image acquisition means) 110 joins (combines) a plurality of images acquired in the time-lapse moving image mode in the order in which they are captured (acquired order) to generate a time-lapse moving image.

Hereinafter, a process related to an imaging operation for acquiring a plurality of images for a time-lapse moving image (hereinafter, simply referred to as an imaging process) will be described with reference to FIG. FIG. 3 is a flowchart illustrating an imaging process according to an embodiment of the present invention. In the following description, it is assumed that the imaging time interval and the total number of imagings are set in advance by the user.

As shown in FIG. 3, when the user gives an instruction to start imaging in the time-lapse moving image mode, the camera control unit 110 reads out the information regarding the imaging time interval and the total number of imagings recorded in the memory 106 in step S301. Next, in step S302, the camera control unit (luminance value acquisition means) 110 acquires the brightness value and the subject distance based on the image acquired by using the sensor 103. Next, in step S303, the exposure control unit 111 executes exposure control based on the previously acquired luminance value, and sets an appropriate exposure for the luminance value. Further, the camera control unit 110 executes the AF control operation based on the previously acquired subject distance. Information such as the acquired luminance value, exposure, and subject distance is recorded in the memory 106 by the recording control unit 108. Next, in step S304, the camera control unit 110 executes imaging (main imaging) using the sensor 103. By this main imaging, the first image used for the generation of the time-lapse movie is acquired. Further, in step S304, the camera control unit 110 starts time measurement by a timer (not shown) provided inside the camera control unit 110.

Here, a method of setting the non-exposure tracking range ΔBvTH in the time-lapse moving image mode will be described. As described above, the camera 100 has a configuration in which the acquisition of the luminance value and the exposure control based on the luminance value are executed each time each imaging in the intermittent imaging is executed in the time-lapse moving image mode. That is, the camera 100 of the present embodiment can automatically change the exposure (hereinafter, referred to as exposure tracking) according to the change in the brightness value each time the continuous imaging is performed. By executing this exposure tracking, it is possible to acquire a brightness image according to a change in the brightness value in each of the continuous imaging, so that the brightness of the entire image is obtained between a plurality of images acquired by the continuous imaging. It is possible to make the brightness according to the change in the brightness value. However, when exposure tracking is simply executed, the brightness of the entire image is set to the brightness according to the change in the brightness value between the plurality of images, so that the brightness of the subject in the image is adjusted between the plurality of images. There will be variations.

FIG. 4 illustrates this situation exemplarily. FIG. 4 is a diagram illustrating a change in the luminance value when performing intermittent imaging, and shows a case where the imaging time interval is set to 30 seconds. In the graph of FIG. 4, the horizontal axis shows the elapsed time, the vertical axis shows the luminance value, and the solid line shows the change in the luminance value. Further, the lower part of FIG. 4 shows images continuously acquired in the range surrounded by the broken line.

As shown in FIG. 4, when exposure tracking is performed in intermittent imaging, for example, the brightness of a person other than the person (building, background, etc.) in the image is also changed according to a change in the brightness of the person in the image. It will change. That is, when the exposure tracking is performed, the brightness of another subject (other part) also changes according to the change in the brightness of a predetermined subject (part) in the image.

Therefore, simply executing exposure tracking in the time-lapse moving image mode causes variations in the brightness of the subject in each image among a plurality of images acquired by continuous imaging. In this case, by stitching together a plurality of images in which the brightness of the subject varies, a time-lapse movie in which the brightness flickers between frames is acquired. That is, the quality of the time-lapse moving image is deteriorated due to the variation in the brightness of the subject among the plurality of images.

In order to solve this problem, it is conceivable to set a range (non-exposure tracking range) ΔBvTH in which the exposure is not changed (exposure tracking is not performed) according to the change in the brightness value. This non-exposure tracking range ΔBvTH is a range (related to the brightness value) set based on the brightness value acquired by the camera control unit 110. In the present embodiment, the exposure control unit 111 sets the range of the brightness value based on the acquired brightness value as the non-exposure tracking range BvTH. For example, when the non-exposure tracking range ΔBvTH is ± 1.0 step, the range of ± 1 Bv in APEX units with respect to the acquired luminance value is a range (dead zone) in which the exposure is not changed according to the change of the luminance value. By adopting this configuration, it is possible to prevent the brightness of each subject from fluctuating (frequently changing) among a plurality of images. This situation will be exemplarily described with reference to FIG. FIG. 5 is a diagram illustrating a change in brightness between images acquired when the non-exposure tracking range ΔBvTH is set and intermittent imaging is performed. As shown in FIG. 5, by not changing the exposure until the brightness value changes beyond the non-exposure tracking range ΔBvTH, it is possible to suppress the variation in the brightness of the subject among a plurality of images acquired in the time-lapse movie mode. ..

However, when intermittent imaging is performed, the degree of change in the brightness value differs depending on the imaging time interval of continuous imaging. Therefore, if the magnitude of the non-exposure tracking range ΔBvTH is set without considering the imaging time interval, the brightness between a plurality of images may change unnaturally. The details will be described with reference to FIG. FIG. 6 is a diagram illustrating a change in the brightness value and a change in the brightness of a plurality of images when the imaging time interval in the time-lapse moving image mode is 1 hour. As shown in FIG. 6, when the imaging time interval is relatively long, such as 1 hour, there is a high probability that the brightness of the entire image will change due to the change in ambient light. In other words, when the imaging time interval of intermittent imaging is relatively long, there is a high probability that the change in brightness value that occurs between continuous imaging will occur due to the change in ambient light. Therefore, when the imaging time interval is relatively long in the time-lapse moving image mode, if the non-exposure tracking range ΔBvTH is wide, the brightness of the entire image changes stepwise until the brightness value changes beyond the non-exposure tracking range ΔBvTH. To do. Then, the brightness of the entire image suddenly changes according to the change in the brightness value beyond the non-exposure tracking range ΔBvTH.

On the other hand, when the imaging time interval in intermittent imaging is relatively short, such as 30 seconds, there is a high probability that the change in the brightness value is caused by the instantaneous change in the brightness of the subject. In other words, in this case, the probability that the brightness value changes according to the change in ambient light is low. In this case, if the non-exposure tracking range ΔBvTH is narrow, the brightness of the subject varies among a plurality of images each time the brightness value changes beyond the non-exposure tracking range ΔBvTH.

To summarize the above, when the imaging time interval of intermittent imaging is relatively long, if a wide non-exposure tracking range ΔBvTH is set, a plurality of images in which the brightness of the entire image changes unnaturally are acquired. It ends up. In addition, when the imaging time interval of intermittent imaging is relatively short, if a narrow non-exposure tracking range ΔBvTH is set, a plurality of images in which the brightness of the subject in the image changes unnaturally are acquired. It ends up. Therefore, if a time-lapse movie is generated using a plurality of images acquired in the above-mentioned state, a video with reduced quality due to brightness flicker between frames will be acquired, so that the user who viewed the video will be notified. It gives a sense of discomfort. Therefore, the camera 100 of the present embodiment solves the above-mentioned problem by controlling the magnitude of the non-exposure tracking range BvTH based on the information regarding the time for performing the intermittent imaging when the intermittent imaging is performed. Correspond. The details will be described below.

Returning to FIG. 3, in step S305, the camera control unit (determining means) 110 determines whether or not the (main) subject to be imaged is located indoors. Any method may be adopted for the process of step S305 as long as it can be determined whether or not the subject to be imaged is located indoors. In the present embodiment, the camera control unit 110 determines whether or not the subject to be imaged is located indoors by determining whether or not the camera 100 is located indoors. Specifically, in the camera control unit 110, the camera 100 is located indoors when the previously acquired luminance value is Bv4 or less in APEX units and the subject distance is smaller than 5 m, and the camera 100 is otherwise. Determined to be located outdoors. Based on the result of the determination, the camera control unit 110 determines that the subject to be imaged is located indoors when the camera 100 is determined to be located indoors, and determines that the camera 100 is not located indoors. In this case, it is determined that the subject to be imaged is located outdoors. The brightness value and the subject distance used for the above determination are not limited to those described above, and any value may be adopted as long as it can be determined that the camera 100 is located indoors. In addition, the determination may be executed based on at least the previously acquired luminance value.

The process of step S305 may be executed by the camera control unit 110 based on the position information of the camera 100 acquired by using a positioning system such as GPS (Global Positioning System). Further, the process of step S305 may be executed based on the information manually input by the user. That is, the position of the subject to be imaged may be determined based on the information about the position of the subject to be imaged manually set by the user.

When the camera control unit 110 determines that the subject to be imaged is located indoors, it is considered that the fluctuation of the ambient light is small around the subject. Therefore, in step S306, the exposure control unit 111 sets the non-exposure tracking range ΔBvTh to ± 1.0 steps. The non-exposure tracking range ΔBvTH set in step S306 may be any value as long as it is a relatively wide fixed value. With this configuration, in the time-lapse moving image mode, it is possible to prevent the quality of the acquired moving image from deteriorating when the subject located indoors where the fluctuation of the ambient light is small is imaged.

Next, in step S307, the camera control unit 110 determines whether or not the set imaging time interval is 30 seconds or less. When the camera control unit 110 determines that the imaging time interval is 30 seconds or less (YES in step S207), the exposure control unit (range setting unit) 111 sets the non-exposure tracking range ΔBVTH by ± 1.0 steps in step S308. Set to. In this case, as shown in FIG. 5, the brightness value corresponding to the second imaging performed in pairs at a predetermined time interval after the first imaging is set with respect to the brightness value corresponding to the first imaging. The exposure at the time of the second imaging is not changed until the change is larger than 1 Bv. Therefore, as shown in the lower part of FIG. 5, the camera 100 can suppress variations in the brightness of the subject among a plurality of images acquired by performing continuous imaging.

Similar to steps S307 to S308 described above, in the subsequent processes of steps S309 to S316, the exposure control unit (range setting unit means) 111 sets the non-exposure tracking range ΔBvTH based on the previously set imaging time interval. .. For example, when the imaging time interval is longer than 30 seconds and 30 minutes or less, the exposure control unit 111 sets the non-exposure tracking range ΔBvTH to ± 0.5 steps (steps S309 to S310). When the imaging time interval is longer than 30 minutes and 1 hour or less, the exposure control unit 111 sets the non-exposure tracking range ΔBvTH to ± 0.3 steps (steps S311 to S312). When the imaging time interval is longer than 1 hour and 5 hours or less, the exposure control unit 111 sets the non-exposure tracking range ΔBvTH to ± 0.1 steps (steps S313 to S314). Further, when the imaging time interval is longer than 5 hours and 24 hours or less, the exposure control unit 111 sets the non-exposure tracking range ΔBvTH to 0 stage (steps S315 to S316). That is, in this case, the non-exposure tracking range ΔBvTH is not set.

In the processing of steps S306 to S316 described above, the range (magnitude) of the non-exposure tracking range ΔBvTH that can be set is set to ± 1.0 step (large), ± 0.5 step (medium), and ± 0.3. The steps are (small), ± 0.1 steps (minimum), and 0 steps, but the present invention is not limited to these. The magnitude of the non-exposure tracking range ΔBvTH that can be set by the camera 100 may be other than those described above. Further, the time interval used for comparison with the imaging time interval set by the user is not limited to the above-mentioned one, and may be configured to adopt another time interval. For example, the exposure control unit 111 sets the non-exposure tracking range ΔBvTH to ± 2.0 steps when the imaging time interval is 1 minute or less, and is non-exposure when the imaging time interval is 8 hours or more and 24 hours or less. The follow-up range ΔBvTH may be set to 0.05 steps. For the camera 100 of the present embodiment, at least, the longer the imaging time interval in intermittent imaging, the narrower (smaller) the non-exposure tracking range ΔBvTH is set, and the shorter the imaging time interval, the wider (larger) the non-exposure tracking range ΔBvTH. ) Any configuration may be used. That is, the exposure control unit 111 is more likely to have a second interval set, which is a longer time interval than the first interval, than when the imaging time interval is set to the first interval. , The non-exposure tracking range ΔBvTH is narrowed (reduced). With this configuration, the camera 100 of the present embodiment can perform exposure control so that the brightness of the entire screen and the subject can be smoothly changed between a plurality of images when performing intermittent imaging. Therefore, the camera 100 of the present embodiment can acquire a moving image in which brightness flicker is suppressed by joining a plurality of images acquired in this state. FIG. 7 is a diagram for exemplifying this situation, and is a diagram for exemplifying changes in the brightness of a plurality of images acquired by the imaging process according to the embodiment of the present invention. The change in the luminance value in FIG. 7 is substantially the same as the change in the luminance value in FIG. 6 described above. As shown in FIG. 7, the camera 100 of the present embodiment sets the magnitude of the non-exposure tracking range ΔBvTH according to the imaging time interval of intermittent imaging, so that the brightness varies for time-lapse moving images. It is possible to acquire a plurality of suppressed images. Therefore, the camera 100 of the present embodiment can suppress deterioration of the quality of a moving image obtained by joining a plurality of acquired images by performing intermittent imaging.

Return to FIG. In step S317, when the previously set imaging time interval is 24 hours or more, the camera control unit 110 determines the magnitude of the non-exposure tracking range ΔBvTH based on the difference between the imaging time interval and the predetermined time interval. Set. Specifically, the camera 100 subtracts approximately 24 hours from the imaging time interval set by the user, and returns to the process of step S307. When imaging is performed outdoors, there is a high probability that substantially the same change in ambient light will occur in a cycle of one day (24 hours). Therefore, the camera 100 of the present embodiment uses the time interval obtained by subtracting approximately 24 hours from the imaging time interval when the imaging time interval of continuous imaging is 24 hours or more by executing the process of step S317. The non-exposure tracking range ΔBvTH is set. For example, when the previously set imaging time interval is 25 hours, the time interval obtained by subtracting 24 hours from 25 hours is 1 hour, so the exposure control unit 111 sets the non-exposure tracking range ΔBvTH to ± 0.3 steps. To do. In step S317, the predetermined time interval to be subtracted from the imaging time interval does not have to be exactly 24 hours, and for example, 24 hours ± 5 minutes may be set as the predetermined time interval. Further, since the change cycle of the ambient light differs depending on the region and the date and time, in step S317, the predetermined time interval to be subtracted from the imaging time interval may be a time interval other than 24 hours.

Next, in step S318, the camera control unit 110 determines whether or not the time measurement by the timer (not shown) has reached the next imaging time. Specifically, the camera control unit 110 determines whether or not the elapsed time from the previous imaging time has reached a time obtained by subtracting a predetermined preparation time (for example, 10 seconds) from the previously set time interval. It is determined whether or not the next imaging time has been reached. The process of step S318 is repeated until the time measurement by the timer reaches the next imaging time.

Next, in step S319, the camera control unit 110 newly acquires the luminance value based on the image acquired by using the sensor 103. Next, in step S320, the camera control unit 110 determines whether or not the current luminance value acquired in step S319 is included in the currently set non-exposure control range ΔBvTH. If the camera control unit 110 determines that the current luminance value is not included in the non-exposure tracking range ΔBvTH (NO in step S320), the process proceeds to step S321. In step S321, the exposure control unit 111 executes exposure control and changes the exposure based on the brightness value acquired in step S319. Then, a new non-exposure tracking range ΔBvTH is set based on the luminance value acquired in step S319. The new non-exposure tracking range ΔBvTH is set to have the same magnitude as the previously set non-exposure tracking range ΔBvTH (for example, by the processing of steps S306 to S316). Further, in step S321, the exposure control unit 111 changes the exposure by giving priority to changing the shooting sensitivity and the shutter speed. With this configuration, it is possible to suppress variations in the depth of field and minute differences in brightness due to the mechanical operation of the aperture 102 among the acquired plurality of images.

If the camera control unit 110 determines that the current luminance value is included in the non-exposure tracking range ΔBvTH (YES in step S320), the process proceeds to step S322. In step S322, the exposure control unit 111 proceeds to the process of step S323 without changing the exposure that has already been set. That is, in step S322, the camera 100 maintains the exposure set at the time of the previous step imaging. In the present embodiment, the lens position of the focus lens is not changed in one continuous imaging, but the AF control may be executed again by the process of step S321 or step S322.

Next, in step S323, the camera control unit 110 executes imaging using the sensor 103, and ends the time measurement currently being processed by the timer (not shown). Then, the recording control unit 108 records the image acquired by imaging in the memory 106. Next, in step S324, the camera control unit 110 determines whether or not the number of imagings up to now has reached the previously set total number of imagings. When the camera control unit 110 determines that the total number of imaging times has been reached (YES in step S324), the camera control unit 110 ends the current imaging process. If the camera control unit 110 determines that the total number of imaging times has not been reached (NO in step S324), the camera control unit 110 starts a new time measurement using the timer and returns to the process of step S318. The above is the imaging process of the present embodiment.

When a plurality of images that are continuous in time are acquired by the imaging process, the camera control unit (moving image acquisition means) 110 acquires (generates) a time-lapse moving image by joining the plurality of images in the order in which the images were taken. To do. The acquired time-lapse movie is recorded in the memory 106 by the recording control unit 108. The time-lapse moving image may be acquired after the imaging process is completed, or may be acquired in parallel with the imaging process. Further, a plurality of images acquired by the imaging process may be sent to an external device or the like provided outside the camera 100, and the external device may generate a time-lapse moving image. In this case, the camera control unit (moving image acquisition means) 110 may acquire the time-lapse moving image generated by an external device or the like.

As described above, the camera 100 of the present embodiment sets the non-exposure tracking range ΔBvTH based on the imaging time interval of intermittent imaging. With this configuration, the camera 100 of the present embodiment can set the non-exposure tracking range ΔBvTH having an optimum size based on the imaging time interval, so that the brightness of the entire image and the subject changes unnaturally. It is possible to acquire a plurality of images in which the image is suppressed. Therefore, the camera 100 of the present embodiment can suppress deterioration of the quality of a moving image obtained by joining a plurality of acquired images by performing intermittent imaging.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and modifications can be made within the scope of the gist thereof. For example, in the above-described embodiment, the size of the non-exposure tracking range ΔBvTH once set in a series of intermittent imaging is not changed, but the present invention is not limited to this. For example, in response to a change in the imaging time interval by the user while the imaging process is in progress and the non-exposure tracking range ΔBvTH has already been set, the non-exposure tracking range ΔBvTH is based on the changed imaging time interval. The size of the above may be changed. Further, in the above-described embodiment, the non-exposure tracking range ΔBvTH is set after performing the first imaging in the intermittent imaging, but the present invention is not limited to this. For example, the exposure control unit 111 may be configured to set the non-exposure tracking range ΔBvTH based on the information regarding the time for executing continuous imaging before executing the first imaging of the intermittent imaging. ..

Further, in the above-described embodiment, when the imaging time interval is longer than 5 hours and is 24 hours or less, the non-exposure tracking range is uniformly set to 0 (ΔBvTH = 0). It is not limited. That is, in the above-described embodiment, the predetermined one cycle in which the change in the ambient light is assumed to change in a certain direction is set to 24 hours, but the present invention is not limited to this.

For example, a predetermined cycle may be set to a time interval other than 24 hours. Specifically, when a predetermined cycle is set to 17 hours, the non-exposure tracking range ΔBvTH is gradually set smaller as the imaging time interval becomes longer while the imaging time interval is up to 17 hours. Then, when the imaging time interval exceeds 17 hours, a determination for setting the non-exposure tracking range ΔBvTH is executed again using the value obtained by subtracting 17 hours from the imaging time interval (imaging time interval).

With this configuration, for example, when the brightness of the ambient light changes almost the same during the day, such as at sunrise and sunset, appropriate non-exposure tracking according to the imaging time interval is supported. The range ΔBvTH can be set. The predetermined period in which the change in ambient light is expected to change in a certain direction may be set based on a manual operation by the user, or a default value preset inside the camera 100 may be used. You may.

As described above, as the imaging apparatus according to the above-described embodiment, at least, the longer the imaging time interval in a predetermined cycle, the narrower the non-exposure tracking range ΔBvTH is set, and the shorter the imaging time interval, the wider the non-exposure tracking range ΔBvTH is set. Any configuration may be used. Further, in the above-described embodiment, the non-exposure tracking range ΔBvTH is set based on the continuous imaging time interval as the information regarding the time for executing the intermittent imaging, but the present invention is limited to this. is not. For example, as the information regarding the time for executing the intermittent imaging, the non-exposure tracking range ΔBvTH in the time-lapse moving image mode may be set based on the information regarding the time zone for executing the continuous imaging. Hereinafter, this configuration will be specifically described.

For example, in the memory 106, 24 hours are divided into 1 minute units in the morning (5: 00 to 6:59), noon (7: 00 to 15:59), evening (16:00 to 18:59), and night (19: Data divided into four time zones (00 to 4:59) is stored in advance. When performing intermittent imaging, the camera control unit 110 sets the non-exposure tracking range ΔBvTH based on the difference between the time zones in which continuous imaging is executed among the plurality of time zones described above. For example, when a continuous first imaging and a second imaging are continuously performed in the "day" and "evening" time zones, the difference between the time zones in which the continuous imaging is executed is one step (first). The difference). On the other hand, when the first imaging and the second imaging are continuously performed in the "day" and "night" time zones, the difference between the two time zones is two steps (second difference). It becomes.

As described above, when the difference between the time zones in which continuous imaging is executed is one step, the probability that the brightness value changes due to the change in ambient light is relatively small, so that the exposure control unit 111 has The non-exposure tracking range ΔBvTH is set to ± 0.5 steps. Further, when the difference between the time zones for executing continuous imaging is two steps, the probability that the brightness value changes due to the change in the ambient light is relatively large, so that the exposure control unit 111 follows the non-exposure. The range ΔBvTH is set to ± 0.1 steps. That is, the exposure control unit 111 narrows (reduces) the non-exposure tracking range ΔBvTH as the difference between the time zones in which continuous imaging is executed increases. Even with an imaging device that employs the configuration described above, it is possible to suppress an unnatural change in the brightness of a moving image obtained by joining a plurality of acquired images by performing intermittent imaging.

For example, when the first imaging is performed in the "morning" time zone and the second imaging is performed in the "night" time zone, the difference between the time zones in which continuous imaging is performed is one step. To do. That is, the difference between the time zones in which continuous imaging is executed is set based on the absolute value of the difference between the time zones in which continuous imaging is executed in 24 hours. Further, the plurality of time zones described above are not limited to morning, noon, evening, and night, and other time zones may be adopted. Further, the time zones of morning, noon, evening, and night are not limited to the above-mentioned time setting. Since the time during which the ambient light changes within 24 hours changes depending on the area, the date and time, etc., for example, the morning time zone may be set from 5 o'clock to 7 o'clock.

When the imaging time interval set by the user is 3 hours, if the imaging is performed at 8 o'clock, the next imaging is performed at 11 o'clock, so that the change in the environment is considered to be relatively small. On the other hand, even if the imaging time interval is the same for 3 hours, if the imaging is performed at 15:00, the next imaging is performed at 18:00, so that the change in ambient light is considered to be relatively large. That is, even if the imaging time intervals are the same, the degree of change in the ambient light differs depending on the difference between the time zones in which continuous imaging is performed. Therefore, the camera 100 may be configured to set the exposure tracking range ΔBvTH based on both the imaging time interval for performing intermittent imaging and the information regarding the time zone for performing imaging. As the camera 100 adopting this configuration, for example, even if the imaging time intervals are the same, the magnitude of the non-exposure tracking range ΔBvTH is changed according to the time for starting continuous imaging. Specifically, when the imaging time intervals are the same, the exposure control unit 111 is the first of continuous imaging than when the first imaging of continuous imaging is started in the "morning" or "evening" time zone. The exposure tracking range ΔBvTH is set wider when the imaging of the image is started at “day” or “night”.

As described above, the camera 100 according to the embodiment of the present invention has a configuration in which the non-exposure tracking range is set at least based on information on the continuous imaging time when performing intermittent imaging. It should be. The camera 100 adopting this configuration can suppress unnatural changes in the brightness (flickering) of a moving image obtained by joining a plurality of acquired images by performing intermittent imaging. Therefore, the camera 100 can suppress the deterioration of the quality of the moving image obtained by joining the plurality of images acquired by performing the intermittent imaging.

Further, in the above-described embodiment, the non-exposure tracking range ΔBvTH is set as the range of the luminance value, but the present invention is not limited to this. For example, the non-exposure tracking range ΔBvTH may be set to a range based on the exposure (exposure control value) corresponding to the acquired luminance value.

Further, in addition to the above-described embodiment, for example, when the exposure control unit 111 detects that the brightness value exceeds the non-exposure tracking range ΔBvTH and continuously changes in the same brightness direction a plurality of times, It may be configured to change the exposure. The camera 100 adopting this configuration can accurately determine whether or not the brightness value has changed due to a change in ambient light, and can perform exposure control. The camera 100 adopting this configuration more accurately determines that the change in the brightness value is caused by the change in the ambient light by increasing the number of acquisitions of the brightness value more than the total number of times of imaging. be able to. For example, when the camera control unit 110 executes intermittent imaging, and the total number of imaging times is set to 10 and the imaging time interval is set to 1 hour, 30 after the first imaging is started. Get the brightness value at minute intervals. In this case, the brightness value is acquired only twice the total number of times of imaging (20 times). Then, the exposure control unit 111 changes the acquired luminance value beyond the non-exposure tracking range ΔBvTH as the exposure control at the time of each imaging, and the change of the luminance value and the luminance value acquired immediately before the exposure changes in the same direction. If so, change the exposure. The camera 100 adopting this configuration can shorten the time required from the change in the brightness value to the change in the exposure when performing intermittent imaging.

Further, the camera 100 may be configured to shift the state of the camera 100 to a standby state (power saving state) during continuous imaging in the imaging process in addition to the above-described embodiment. Specifically, the camera control unit 110 sets the state of the camera 100 to the standby state during the period from the setting of the non-exposure tracking range ΔBvTH to the completion of the processing of S318. In this standby state, for example, the supply of electric power to each unit other than the camera control unit 110 is stopped, and only the operation of the camera 100 related to the processing of step S318, such as time measurement by a timer, is performed. The camera 100 adopting the above configuration can suppress power consumption in the time-lapse moving image mode.

Further, in the above-described embodiment, in order to acquire the luminance value and the subject distance, preliminary imaging is performed before the main imaging (image acquisition for time-lapse moving image generation), but the present invention is not limited to this. Absent. For example, the camera 100 may be configured to acquire information on the luminance value and the subject distance based on the image acquired in the previous main imaging in the imaging process. In particular, when the imaging time interval for performing intermittent imaging is relatively short (for example, 5 minutes or less), the probability that the brightness value changes due to the change in ambient light is low. Therefore, in this case, even if the exposure control is performed using the brightness value based on the image acquired in the previous main imaging without executing the preliminary imaging, the image with appropriate brightness according to the change in the brightness value is used. Can be obtained.

In the above-described embodiment, a configuration in which a subject is imaged at each imaging time interval in order to acquire an image for a time-lapse moving image has been described, but the present invention is not limited to this. For example, in a configuration in which a moving image is continuously acquired from the start of imaging and an image for a time-lapse movie is set (thinned out) from a plurality of images (frames) constituting the moving image based on an imaging time interval. Also, the characteristic configuration of the present invention described above is applicable. In this case, at least, as the frame rate of the moving image, a frame rate for acquiring the image at a cycle shorter than the imaging time interval that can be set as a time-lapse moving image is set.

Further, in the above-described embodiment, the image processing unit 105, the memory 106, the recording control unit 108, the camera control unit 110, the exposure control unit 111, and the like operate in cooperation with each other to control the operation of the camera 100. There was, but it is not limited to this. For example, a (computer) program according to the flow shown in FIG. 2 is stored in the memory 106 in advance, and the camera control unit 110 including the microcomputer executes the program to control the operation of the camera 100. It may have such a configuration.

Further, as long as it has a program function, the form of the program such as object code, a program executed by an interpreter, script data supplied to the OS, etc. does not matter. Further, the recording medium for supplying the program may be, for example, a hard disk, a magnetic recording medium such as a magnetic tape, or an optical / optical magnetic recording medium.

Further, in the above-described embodiment, the digital camera has been described as an example of the image pickup apparatus for carrying out the present invention, but the present invention is not limited thereto. For example, a configuration may employ an imaging device other than a digital camera, such as a portable device such as a digital video camera or a smartphone, or a security camera.

(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 read 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.

100 Digital camera 103 Sensor 110 Camera control unit 111 Exposure control unit

Claims (20)

An imaging device that performs intermittent imaging in order to acquire a moving image in which a plurality of images are stitched together.
An imaging means that captures the subject,
A luminance value acquisition means for acquiring a luminance value of a subject to be imaged by the imaging means,
An exposure control means that controls exposure according to the brightness value acquired by the brightness value acquisition means, and
A range setting means for setting a non-exposure tracking range in the exposure control means that does not change the exposure according to a change in the brightness value acquired by the brightness value acquisition means.
Have,
The range setting means is an imaging device characterized in that the non-exposure tracking range is set based on information regarding a time for performing intermittent imaging. The imaging apparatus according to claim 1, wherein the information regarding the time for executing the intermittent imaging is information regarding the time interval for executing the continuous imaging in the intermittent imaging. When performing intermittent imaging, the range setting means has a second interval in which the time interval is longer than the first time interval than in the case where the time interval is the first interval. The imaging apparatus according to claim 2, wherein the non-exposure tracking range is set to be smaller. When the range setting means performs intermittent imaging and the time interval exceeds a predetermined time interval, the range setting means follows the non-exposure based on the difference between the time interval and the predetermined time interval. The imaging apparatus according to claim 3, wherein a range is set. The imaging device according to claim 4, wherein the predetermined time interval is a time interval in which a change in ambient light is in a fixed direction. The imaging device according to claim 4 or 5, wherein the predetermined time interval is approximately 24 hours. The imaging device according to claim 1, wherein the information regarding the time for performing the intermittent imaging is information regarding the time zone for performing the intermittent imaging. The time zone for performing the intermittent imaging is a plurality of time zones obtained by dividing a predetermined time.
When performing intermittent imaging, the range setting means is more intermittent than the case where the difference between the time zones during which the intermittent imaging is performed in the intermittent imaging is the first difference. The imaging according to claim 7, wherein the non-exposure tracking range is set smaller when the difference between the time zones in which the imaging is performed is a second difference larger than the first difference. apparatus. The imaging device according to claim 8, wherein the time zone for performing the intermittent imaging is a plurality of time zones including morning, noon, evening, and night. When the range setting means performs the intermittent first imaging and the second imaging, the range setting means is based on the first luminance value corresponding to the first imaging and is based on the first luminance value. The imaging apparatus according to any one of claims 1 to 9, wherein the non-exposure tracking range, which is a range of the obtained luminance values, is set. When the second luminance value corresponding to the second imaging is included in the non-exposure tracking range, the exposure control means does not change the exposure according to the second luminance value, and the second exposure control means does not change the exposure. The imaging apparatus according to claim 10, wherein the exposure is changed according to the second luminance value when the luminance value is not included in the non-exposure tracking range. The range setting means corresponds to the first luminance value based on the first luminance value corresponding to the first imaging when performing the intermittent first imaging and the second imaging. The imaging apparatus according to any one of claims 1 to 8, wherein the non-exposure tracking range, which is an exposure range based on exposure, is set. When the exposure based on the second luminance value corresponding to the second imaging is included in the non-exposure tracking range, the exposure control means does not change to the exposure based on the second luminance value. The imaging apparatus according to claim 12, wherein when the exposure corresponding to the second luminance value is not included in the non-exposure tracking range, the exposure is changed to the exposure based on the second luminance value. .. Claims 1 to 13 are characterized in that the moving image in which the plurality of images are joined is a moving image in which the temporal change is compressed by joining the plurality of images continuously and intermittently. The imaging apparatus according to any one of the above. The moving image obtained by joining the plurality of images is a moving image obtained by joining the plurality of images obtained by performing imaging with a time interval of at least about 1 second or more using the imaging means. The imaging apparatus according to any one of claims 1 to 14, which is characterized. The claim is characterized in that it has a moving image acquisition means for acquiring a moving image in which a plurality of images obtained by executing intermittent imaging are joined in the order in which the imaging is executed. The imaging apparatus according to any one of 1 to 15. The exposure control means can change the exposure by changing the aperture value, the shutter speed, and the shooting sensitivity, and when performing intermittent imaging, the shutter speed and the above are described according to the change in the brightness value. The imaging apparatus according to any one of claims 1 to 16, wherein the exposure is changed by giving priority to the shooting sensitivity. It has a determination means for determining whether or not the subject to be imaged is located indoors.
The range setting means is a case where intermittent imaging is performed, and when the determination means determines that the subject to be imaged is located indoors, the non-exposure tracking range is set to a predetermined range preset. When the subject to be imaged is not determined to be located indoors by the determination means, the non-exposure tracking range is set based on the information regarding the time for performing the intermittent imaging. The imaging apparatus according to any one of claims 1 to 17. It is a control method of an imaging device that includes an imaging means for imaging a subject and executes intermittent imaging in order to acquire a moving image in which a plurality of images are stitched together.
It has a range setting step of setting a non-exposure tracking range without changing the exposure according to a change in the brightness value of the subject acquired in correspondence with the imaging using the imaging means.
The range setting step is a control method for an imaging device, which comprises setting the non-exposure tracking range based on information about a time for performing intermittent imaging. A computer-readable program for causing a computer to execute the control method of the imaging device according to claim 19.

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