Imaging device, control method of imaging device, and control program of imaging device

Abstract

To appropriately switch an imaging mode in accordance with an ambient brightness.SOLUTION: An imaging device includes a control part that performs a process of switching an imaging mode from a day mode to a night mode when a gain value is equal to or greater than a predetermined value in the case where the imaging mode is the day mode, stores an illuminance value around an imaging unit at the time of the process as a switching threshold in a storage unit, and performs a process of switching the imaging mode from the night mode to the day mode when a detection result of a visible light sensor is equal to or greater than the switching threshold stored in the storage unit in a case where the imaging mode is the night mode. When the process of switching to the night mode is performed in the case where the imaging mode is the day mode, the control part sets, as the switching threshold to be stored in the storage unit, either the detection result of the visible light sensor at the time of the process or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value, in accordance with a change rate of the illuminance around the imaging unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an imaging device, a control method for an imaging device, and a control program for an imaging device. [Background technology]

[0002] BACKGROUND ART In imaging devices such as surveillance cameras, imaging modes are switched depending on the ambient brightness (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-50028 Summary of the Invention [Problem to be solved by the invention]

[0004] In the imaging device described above, it is required to appropriately switch the imaging mode according to the ambient brightness.

[0005] The present invention has been made in consideration of the above, and aims to provide an imaging device, a control method for an imaging device, and a control program for an imaging device that are capable of appropriately switching imaging modes according to ambient brightness. [Means for solving the problem]

[0006] an image signal processing unit that adjusts a gain value so as to maintain a luminance value of an image signal output from the image capturing unit within a certain range and processes the image signal to convert the color of the image signal to color or black and white; a visible light sensor that detects the illuminance around the image capturing unit; and a control unit that, when the image capturing mode is the day mode, performs a process of switching the image capturing mode from the day mode to the night mode if the gain value becomes equal to or greater than a predetermined value, and stores the illuminance value around the image capturing unit at the time of the process as a switching threshold in a memory unit; and, when the image capturing mode is the night mode, performs a process of switching the image capturing mode from the night mode to the day mode if the detection result of the visible light sensor becomes equal to or greater than the switching threshold stored in the memory unit. When the image capturing mode is the day mode and the control unit performs the process of switching to the night mode, the control unit sets, as the switching threshold, either the detection result of the visible light sensor at the time of the process or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value, depending on the rate of change of the illuminance around the image capturing unit,

[0007] a gain value that maintains the luminance value of an image signal output from the imaging unit within a certain range and processes the image signal to convert the color of the image signal to color or black and white; and a visible light sensor that detects illuminance around the imaging unit; wherein, when the imaging mode is the day mode, if the gain value becomes equal to or greater than a predetermined value, a process is performed to switch the imaging mode from the day mode to the night mode, and the illuminance value around the imaging unit at the time of this process is stored in a memory unit as a switching threshold; and, when the imaging mode is the night mode, if a detection result of the visible light sensor becomes equal to or greater than the switching threshold stored in the memory unit, a process is performed to switch the imaging mode from the night mode to the day mode; and when the imaging mode is the day mode and the process of switching to the night mode is performed, the switching threshold is either the detection result of the visible light sensor at the time of this process or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value, depending on the rate of change of illuminance around the imaging unit, and the switching threshold is stored in the memory unit.

[0008] A control program for an imaging device according to the present invention is a control program for an imaging device including an imaging unit capable of capturing images by switching between a day mode and a night mode, an image signal processing unit that adjusts a gain value so as to maintain a luminance value of an image signal output from the imaging unit within a certain range and processes the color of the image signal to be color or black and white, and a visible light sensor that detects illuminance around the imaging unit, wherein when the imaging mode is the day mode, if the gain value becomes equal to or greater than a predetermined value, the imaging mode is switched from the day mode to the night mode, and the illuminance value around the imaging unit at the time of the processing is set as a switching threshold. a process of switching the imaging mode from the night mode to the day mode when the detection result of the visible light sensor becomes equal to or greater than the switching threshold value stored in the storage unit when the imaging mode is the night mode; and a process of setting, when the imaging mode is the day mode and the processing of switching to the night mode is performed, either the detection result of the visible light sensor at the time of the processing or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value, as the switching threshold value to be stored in the storage unit, depending on the rate of change of illuminance around the imaging unit. [Effects of the Invention]

[0009] According to the present invention, it is possible to appropriately switch the imaging mode according to the ambient brightness. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a functional block diagram showing an example of an imaging device according to this embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of an operation when switching from the day mode to the night mode. [Figure 3] FIG. 3 shows an example of operation when the ambient brightness suddenly becomes dark in day mode. [Figure 4]FIG. 4 is a flowchart showing an example of a control method for the imaging device according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of an imaging device, a control method for an imaging device, and a control program for an imaging device according to the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical.

[0012] Fig. 1 is a functional block diagram showing an example of an imaging device according to this embodiment. As shown in Fig. 1, the imaging device 100 includes an imaging unit 10, an image signal processing unit 20, a communication unit 30, a visible light sensor 40, an infrared light illumination unit 50, and a control unit 60. The imaging device 100 may be used for any purpose, such as a surveillance camera installed at a predetermined location inside or outside a facility.

[0013] The imaging unit 10 includes an optical element 11, an infrared cut filter 12, and an imaging element 13. The optical element 11 is an element of an optical system such as a lens. There may be one or more optical elements 11.

[0014] The infrared cut filter 12 is a filter that cuts infrared rays. Whether or not the infrared cut filter 12 is inserted into the optical path of the optical element 11 can be selected under the control of the control unit 60. When the infrared cut filter 12 is inserted into the optical path of the optical element 11, light from which infrared light has been cut is incident on the image sensor 13. When the infrared cut filter 12 is not inserted into the optical path of the optical element 11, light from which infrared light has not been cut is incident on the image sensor 13.

[0015] The imaging element 13 is an element that converts light incident through the optical element 11 into an image signal, which is an electrical signal. Examples of the imaging element 13 include a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor. The imaging element 13 outputs the converted image signal to the image signal processing unit 20.

[0016] The image signal processing unit 20 has an AGC unit 21 and a signal processing unit 22. The AGC unit 21 processes the image signal received from the imaging unit 10 so as to maintain a constant brightness level. The AGC unit 21 sends gain information indicating a gain value to the control unit 60.

[0017] The signal processing unit 22 processes the image signal received from the AGC unit 21. Under the control of the control unit 60, the signal processing unit 22 can control whether to process the image signal in color or black and white. The signal processing unit 22 sends luminance information indicating the luminance level of the image signal to the control unit 60. Specifically, the signal processing unit 22 calculates the average value of the luminance level of the entire screen as the luminance information. The signal processing unit 22 may also calculate the average value of the luminance values ​​in a predetermined area within the screen or the luminance value of a specific pixel as the luminance information.

[0018] The communication unit 30 performs wired or wireless communication with external devices and includes an interface such as a network interface card.

[0019] The visible light sensor 40 detects the illuminance in the direction in which the image capture unit 10 captures an image at predetermined time intervals, for example, every 100 msec. The visible light sensor 40 sends the detected illuminance value to the control unit 60.

[0020] The infrared light illumination unit 50 emits infrared light. The infrared light illumination unit 50 is controlled by the control unit 60 to be turned on or off.

[0021] The control unit 60 controls the operation of the imaging device 100. The control unit 60 includes a processing unit 61 and a storage unit 62.

[0022] The processing unit 61 performs various types of information processing and includes a processor such as a CPU (Central Processing Unit) and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0023] The processing unit 61 includes a determination unit 63 and a system control unit 64 .

[0024] The determination unit 63 determines whether to switch the imaging mode of the imaging device 100 based on the gain information received from the AGC unit 21, the luminance information received from the signal processing unit 22, and the illuminance value information received from the visible light sensor 40. The imaging modes include a day mode and a night mode. The detailed operation of the determination unit 63 will be described later.

[0025] The system control unit 64 controls the overall operation of the imaging device 100. In this embodiment, the system control unit 64 controls switching between day mode and night mode based on the determination result of the determination unit 63. If the determination result of the determination unit 63 is day mode, the system control unit 64 inserts the infrared cut filter 12 into the optical path of the optical element 11, turns off the infrared light illuminator 50, and controls the signal processing unit 22 to perform color processing. If the determination result of the determination unit 63 is night mode, the system control unit 64 does not insert the infrared cut filter 12 into the optical path, turns on the infrared light illuminator 50, and controls the signal processing unit 22 to perform black and white processing. The detailed operation of the system control unit 64 will be described later.

[0026] The storage unit 62 stores information such as various programs and data. The storage unit 62 stores a switching threshold set by the system control unit 64. The storage unit 62 includes storage such as an HDD (Hard Disk Drive) and an SSD (Solid State Drive).

[0027] The storage unit 62 may be configured to control an imaging device including, for example, an imaging unit 10 capable of capturing images by switching between a day mode and a night mode, an image signal processing unit 20 that adjusts a gain value so as to maintain the luminance value of an image signal output from the imaging unit 10 within a certain range and processes the color of the image signal to be color or black and white, and a visible light sensor 40 that detects the illuminance around the imaging unit 10, and when the imaging mode is the day mode, if the gain value becomes equal to or greater than a predetermined value, the imaging mode is switched from the day mode to the night mode, and the illuminance value around the imaging unit 10 at the time of the processing is stored in the storage unit 62 as a switching threshold value. a process of switching the imaging mode from the night mode to the day mode when the detection result of the visible light sensor 40 is equal to or greater than the switching threshold stored in the storage unit 62 when the imaging mode is the night mode; and a process of setting, when the imaging mode is the day mode and the processing of switching to the night mode, either the detection result of the visible light sensor 40 at the time of the processing or an illuminance value calculated based on a virtual gain value, which is a virtual value for the gain value, as the switching threshold to be stored in the storage unit 62, depending on the rate of change in the illuminance around the imaging unit.

[0028] In the control unit 60, the processor in the processing unit 61 reads out various programs and loads them into memory, thereby executing information processing corresponding to the functions of the above-mentioned units. Examples of the various programs include programs received by the communication unit 30, programs stored in the storage unit 62, and programs recorded on an external recording medium. The control unit 60 functions as an information processing device (computer) that executes various information processes. Note that the various programs may be executed by an information processing device other than the control unit 60, or the control unit 60 and the other information processing device may cooperate to execute the various programs.

[0029] Next, a method for switching between image capture modes will be described. The imaging device 100 captures images in day mode when the imaging environment is bright, and captures images in night mode when the imaging environment is dark. In other words, the control unit 60 automatically switches the imaging mode between day mode and night mode depending on the brightness of the imaging environment, thereby capturing images in the imaging mode that corresponds to the brightness of the imaging environment.

[0030] The determination unit 63 can determine whether to switch between day mode and night mode based on the gain value of the AGC unit 21 or the detection value of the visible light sensor 40. In day mode, the gain value of the AGC unit 21 makes it easier to detect changes due to the brightness of the imaging environment than the detection value of the visible light sensor 40. For this reason, the determination unit 63 performs switching control based on the gain value. The gain value of the AGC unit 21, which is the basis for performing switching control, can be set arbitrarily by the user.

[0031] In night mode, the infrared cut filter 12 is removed, so the gain value of the AGC unit 21 tends to be small due to light that includes infrared light (morning sun, infrared lighting), and the operation of switching the imaging mode may not be stable if the decision to switch to day mode is made based on the gain value of the AGC unit 21. For this reason, the decision unit 63 controls the switching based on the detection value of the visible light sensor 40.

[0032] In this embodiment, when switching from day mode to night mode based on the threshold gain value of the AGC unit 21 set by the user, the system control unit 64 stores the detection value of the visible light sensor 40 at the time of switching from day mode to night mode as a switching illuminance value in the storage unit 62. The system control unit 64 switches from night mode to day mode based on the switching illuminance value stored in the storage unit 62. In practice, to provide hysteresis to the switching of the imaging mode, the system control unit 64 can set an illuminance value obtained by adding a predetermined value to the stored switching illuminance value as the illuminance threshold value when switching from night mode to day mode.

[0033] 2 is a diagram illustrating an example of operation when switching from day mode to night mode, and shows graphs G1 to G5.

[0034] Graph G1 shows the change in brightness in the actual imaging environment of the imaging device 100. Graph G1 shows how the brightness of the imaging environment gradually becomes darker.

[0035] Graph G2 shows the luminance value of the image signal converted by the image sensor 13. Graph G2 shows that although the shooting environment is dark, the luminance value of the image signal falls within the control range (Tar_Y±α) of the AGC unit 21 due to the operation of the AGC unit 21.

[0036] Graph G3 shows the illuminance detected by the visible light sensor 40. Graph G3 shows how the detected illuminance decreases as the brightness of the shooting environment changes. The visible light sensor 40 detects the illuminance at a predetermined time interval. The predetermined time may be, for example, 100 msec.

[0037] Graph G4 shows the gain value of the AGC unit 21. As shown in graph G4, as the brightness of the shooting environment decreases, the gain of the AGC unit 21 increases. Therefore, the gain of the AGC unit 21 increases over time.

[0038] Graph G5 shows the intensity of the infrared light illumination unit 50. In the day mode, the infrared light illumination unit 50 is turned off, and therefore the intensity of the infrared light illumination unit 50 is low.

[0039] When the gain of the AGC unit 21 reaches a predetermined threshold (a threshold set by the user: Set_AGC), at time t1 when the gain reaches the predetermined threshold, the determination unit 63 determines to switch to night mode. At time t2, a predetermined time after the determination, the system control unit 64 controls the switching to night mode. Specifically, the system control unit 64 removes the infrared cut filter 12 from the optical path of the optical element 11, turns on the infrared light illumination unit 50, and controls the signal processing unit 22 to perform black and white processing.

[0040] When the gain of the AGC unit 21 reaches a predetermined threshold value Set_AGC at time t1, the system control unit 64 stores in the memory unit 62 a value (V11+a) obtained by adding a predetermined value (a) to the illuminance value V11 detected by the visible light sensor 40 at the first timing after time t1 as a threshold value for switching from night mode to day mode.

[0041] In the night mode, when it is detected that the illuminance value of the visible light sensor 40 has reached the switching threshold value (V11+a), at the time t3 at which this detection is made, the determination unit 63 determines that switching to the day mode should be performed. At a time (not shown) a predetermined time after the switching determination, the system control unit 64 controls switching to the day mode. Specifically, the system control unit 64 inserts the infrared cut filter 12 into the optical path of the optical element 11, turns off the infrared light illumination unit 50, and controls the signal processing unit 22 to perform color processing.

[0042] In this embodiment, when the environmental brightness changes suddenly, the switching from day mode to night mode and the illuminance setting at the time of switching are performed based on the virtual gain value, not the actual gain value of the AGC unit 21.

[0043] FIG. 3 shows an example of operation in day mode when the ambient brightness suddenly becomes dark. Specifically, this may occur when the imaging device 100 is capturing images in day mode in a room with the lights on at night and then the lights are turned off. Note that FIG. 3 shows graphs G6 to G10. In FIG. 3, graph G6 shows the change in brightness in the actual imaging environment of the imaging device 100. Graph G7 shows the luminance value of the image signal converted by the imaging element 13. Graph G8 shows the illuminance detected by the visible light sensor 40. Graph G9 shows the gain value of the AGC unit 21. Graph G10 shows the intensity of the infrared light illumination unit 50.

[0044] First, let us consider a case where only actual gain values ​​are used, without using virtual gain values. When the lights are turned off at time t11 in FIG. 3, the ambient illuminance suddenly becomes dark. The AGC unit 21 operates to increase the gain so as to control the image luminance within the control range (Tar_Y±α), but the increase is gradual compared to the change in ambient illuminance (see graph G9). As a result, the luminance value of the image signal drops sharply at time t11, and then gradually increases (see graph G7).

[0045] Thereafter, when the gain of the AGC unit 21 reaches a predetermined threshold Set_AGC (see graph G9), at time t12 when the gain reaches the predetermined threshold, the determination unit 63 determines to switch the imaging mode from day mode to night mode. The system control unit 64 adds a predetermined value (denoted as a) to the illuminance value V12 detected by the visible light sensor 40 at the first timing after time t12, and stores the resulting value (V12+a) in the storage unit 62 as a threshold for switching from night mode to day mode.

[0046] Subsequently, the ambient brightness gradually increases (see graph G6), and when the value of the visible light sensor 40 reaches the stored value (V12+a) (see graph G8), the determination unit 63 determines to switch to day mode at time t13. When the determination unit 63 determines to switch to day mode, the system control unit 64 controls each unit to switch to day mode. However, when the lights are turned off at time t11, the gain increase operation of the AGC unit 21 is gradual relative to the change in ambient illuminance, and the operation is unable to keep up. Therefore, the detected value of the visible light sensor 40 is detected at time t12, which is later than the intended detection time of time t11, and the detected illuminance value is low. As a result, the detected illuminance at the time of switching to night mode is a low value of V12, and the system switches to day mode at a lower illuminance than expected. For this reason, the gain value of the AGC unit 21 when switching to the day mode at time t13 may be higher than Set_AGC (see graph G9). In this case, the determination unit 63 will again determine that the mode should be switched to the night mode, and the operation of switching the imaging mode will not be stable.

[0047] Next, an example of operation when using a virtual gain value in this embodiment will be described. In this embodiment, a virtual gain value is calculated by correcting the gain value according to the rate of change in environmental illuminance, and a decision to switch from day mode to night mode is made based on the result of comparing the virtual gain value with a threshold value.

[0048] Specifically, in day mode, if the brightness value of the image signal is within the control target range, a switching decision is made based on the actual gain value, and if the brightness value of the image signal is smaller than the control target range, it is determined that the AGC unit 21 operation is not keeping up, and a switching decision is made based on the virtual gain value (Vir_gain: see the dotted line in graph G9).

[0049] where: The Y level (brightness level of the entire screen) at the current time is Y(t), The target value of the Y level is Tar_Y, Let α be the hysteresis with respect to Tar_Y (the width of the control target of the AGC unit 21). Let the gain value of the AGC unit 21 be agc(t). Let the virtual gain value be Vir_gain(t). Let the gain of the AGC unit 21 at the time of switching from the day mode to the night mode be Set_agc. Let the difference between Vir_gain(t) and Set_agc be Δ_gain(t). Let the detection value of the visible light sensor 40 at the time of switching from the day mode to the night mode be V. Let the value of the visible light sensor 40 when the gain of the AGC unit 21 is 0 dB be LS0. Let the value of the visible light sensor 40 at time t be LS(t). Then.

[0050] At this time, agc(t) ≈ 20 log(LS0 / LS(t))... (Equation 1) It becomes.

[0051] When Y(t) ≥ Tar_Y - α, the operation of the AGC unit 21 is catching up. In this case, the determination unit 63 determines the switching from the day mode to the night mode by comparing the gain value of the AGC unit 21 with Set_agc. Also, the system control unit 64 performs the switching illuminance setting based on the gain value of the AGC unit 21.

[0052] On the other hand, when Y(t) < Tar_Y - α, the operation of the AGC unit 21 is not catching up. In this case, the determination unit 63 calculates the virtual gain value (Vir_gain) predicted from the Y level by the following equation.

[0053] Vir_gain(t) = agc(t) + 20Log((Tar_Y - α) / Y(t))... (Equation 2) Also, similar to (Equation 1), Vir_gain(t) = 20log(LS0 / LS(t))... (Equation 3) Set_agc = 20log(LS0 / V)... (Equation 4) It is.

[0054] Here, from (Equation 3) - (Equation 4), Vir_gain(t) - Set_agc = 20log(V / LS(t))…(Equation 5) is obtained.

[0055] Here, assuming Δ_gain(t) = Vir_gain(t) - Set_agc, V = LS(t)·10 (Δ_gain(t) / 20) …(Equation 6) is obtained.

[0056] Also, when Vir_gain(t) > Set_agc and Vir_gain(t - 1) < Set_agc, assuming V1 = LS(t)·10 (Δ_gain(t) / 20) V2 = LS(t - 1)·10 (Δ_gain(t-1) / 20) then V = (V1 + V2) / 2 can be set. Here, t is the reading timing of the visible light sensor 40 next to the time when Vir_gain = Set_agc. Also, t - 1 is the reading timing of the visible light sensor 40 one before t.

[0057] Note that V1 and V2 are almost the same numerical values. To further reduce the error, the average value of V1 and V2 is set as V, but instead of taking the average of V1 and V2, V1 or V2 can also be set as V. Thus, when calculating the switching threshold based on the virtual gain value, the illuminance value that is the average value of the detection results of the visible light sensor 40 before and after the time of performing the process of switching to the night mode can be calculated as the switching threshold.

[0058] When the switching determination is based on the virtual gain value (Vir_gain: see the dashed dotted line in graph G9), the determination unit 63 can determine to switch from day mode to night mode at time t14 when the virtual gain value reaches Set_AGC, as shown in graph G9 in Fig. 3. In this case, the system control unit 64 adds a predetermined value (denoted as a) to V13, which is the average value of the illuminance value V1 detected by the visible light sensor 40 at the timing immediately before time t14 and the illuminance value V2 detected by the visible light sensor 40 at the first timing after time t14, and stores the result (V13+a) in the storage unit 62 as the threshold for switching from the night mode to the day mode.

[0059] Thereafter, the brightness of the environment gradually increases (see graph G6), and when the value of the visible light sensor 40 reaches the stored value (V13+a) (see graph G8), at time t15 when the value reaches the stored value, the determination unit 63 determines to switch to the day mode. When the determination unit 63 determines to switch to the day mode, the system control unit 64 controls each unit to switch to the day mode.

[0060] As described above, in this embodiment, for example, when it is detected that the ambient illuminance suddenly drops and the AGC unit 21 cannot keep up with the change, the decision to switch the imaging mode is made based on the virtual gain value (Vir_gain) obtained by correcting the gain value depending on the rate of change in the illuminance around the imaging unit 10. This allows an appropriate value as the detection value of the visible light sensor 40 to be stored as the switching threshold value in the storage unit 62. In this case, the gain value of the AGC unit 21 when switching to day mode at time t15 is lower than Set_AGC (see graph G9). Therefore, the decision unit 63 does not make a decision to switch to night mode again, and the imaging mode switching operation is stable.

[0061] Fig. 4 is a flowchart showing an example of a control method for the image capture device 100 according to this embodiment. As shown in Fig. 4, first, a gain threshold (Tar_AGC) that serves as a switching reference when switching the image capture mode from day mode to night mode is set (step S10). The value of Tar_AGC may be a predetermined value rather than being set by the user.

[0062] Next, the determination unit 63 determines whether the current imaging mode is the day mode (step S20). If it is determined that the current imaging mode is the day mode (Yes in step S20), the determination unit 63 determines whether the brightness around the imaging device 100 has suddenly become dark (step S30). In step S30, specifically, the determination unit 63 determines whether the luminance value (Y(t)) of the entire screen is equal to or greater than a specified value (Tar_Y-α).

[0063] In step S30, if it is determined that Y(t)≧Tar_Y−α holds (Yes in step S30), the determination unit 63 determines whether the gain value of the AGC unit 21 is equal to or greater than Set_AGC (step S40).

[0064] If it is determined in step S40 that the gain value is equal to or less than Set_AGC (No in step S40), the process returns to step S30 and is repeated. If it is determined in step S40 that the gain value is equal to or greater than Set_AGC (Yes in step S40), the system control unit 64 acquires the illuminance value V=LS(t) detected by the visible light sensor 40 at the first timing after the determination in step S40 (step S50).

[0065] After acquiring the illuminance value, the system control unit 64 switches the imaging mode from day mode to night mode, and sets the switching threshold of the visible light sensor 40 when switching from night mode to day mode as V+a (step S60).

[0066] Thereafter, the determination unit 63 determines whether the illuminance value LS(t) detected by the visible light sensor 40 is equal to or greater than the switching threshold value V+a (step S70). When the determination unit 63 determines that LS(t) < V+a (No in step S70), it repeats the determination in step S70. When the determination unit 63 determines that LS(t) ≥ V+a (Yes in step S70), it switches the imaging mode from the night mode to the day mode (step S80).

[0067] Thereafter, if the operation of the imaging device 100 has not ended (No in step S90), it returns to step S30 and repeats the process. If the operation of the imaging device 100 has ended (Yes in step S90), the process ends.

[0068] On the other hand, in step S20, if it is determined that the current imaging mode is the night mode (No in step S20), it skips to step S70 and performs the process. In this case, the initial setting value V0 is used as the switching threshold value from the night mode to the day mode. Note that V0 can be set as an arbitrary value.

[0069] Also, in step S30, when it is determined that Y(t) < Tar_Y - α (No in step S30), the determination unit 63 calculates the virtual gain value Vir_gain (step S100). After calculating the virtual gain value, the determination unit 63 determines whether the virtual gain value is equal to or greater than Set_AGC (step S110).

[0070] [[ID=十六]]In step S110, when it is determined that Vir_gain < Set_AGC (No in step S110), it returns to step S30 and repeats the process. On the other hand, in step S110, when it is determined that Vir_gain ≥ Set_AGC (Yes in step S110), the system control unit 64 calculates the illuminance value V of the visible light sensor 40 based on the virtual gain value (step S120) and proceeds to step S60.

[0071] As described above, the imaging device 100 according to this embodiment includes the imaging unit 10 that can capture images by switching between day mode and night mode, the image signal processing unit 20 that adjusts the gain value so as to maintain the luminance value of the image signal output from the imaging unit 10 within a certain range and processes the color of the image signal to be color or black and white, the visible light sensor 40 that detects the illuminance around the imaging unit 10, and when the imaging mode is day mode, performs processing to switch the imaging mode from day mode to night mode when the gain value becomes equal to or greater than a predetermined value, and switches the illuminance value around the imaging unit 10 at the time of this processing. The control unit 60 stores the detection result of the visible light sensor 40 as a threshold in the memory unit 62, and when the imaging mode is the night mode, performs processing to switch the imaging mode from the night mode to the day mode when the detection result of the visible light sensor 40 becomes equal to or greater than the switching threshold stored in the memory unit 62. When the imaging mode is the day mode and processing to switch to the night mode is performed, the control unit 60 sets the switching threshold to be stored in the memory unit 62 as either the detection result of the visible light sensor 40 at the time of the processing or an illuminance value calculated based on a virtual gain value, which is a virtual value of the gain value, depending on the rate of change in the illuminance around the imaging unit.

[0072] The control method for an imaging device according to this embodiment is a control method for an imaging device that includes an imaging unit 10 that can capture images by switching the imaging mode between day mode and night mode, an image signal processing unit 20 that adjusts the gain value so as to maintain the luminance value of the image signal output from the imaging unit 10 within a certain range and processes the color of the image signal to either color or black and white, and a visible light sensor 40 that detects the illuminance around the imaging unit 10, wherein when the imaging mode is day mode, if the gain value becomes equal to or greater than a predetermined value, a process is performed to switch the imaging mode from day mode to night mode, and the illuminance value around the imaging unit 10 at the time of this process is stored in memory 62 as a switching threshold, and when the imaging mode is night mode, if the detection result of the visible light sensor 40 becomes equal to or greater than the switching threshold stored in memory 62, a process is performed to switch the imaging mode from night mode to day mode, and when the imaging mode is day mode and the process of switching to night mode is performed, either the detection result of the visible light sensor 40 at the time of this process or an illuminance value calculated based on a virtual gain value, which is a virtual value for the gain value, is used as the switching threshold to be stored in memory 62, depending on the rate of change of the illuminance around the imaging unit.

[0073] The control program for the imaging device according to this embodiment is a control method for an imaging device that includes an imaging unit 10 that can capture images by switching between a day mode and a night mode, an image signal processing unit 20 that adjusts a gain value so as to maintain the luminance value of an image signal output from the imaging unit 10 within a certain range and processes the color of the image signal to be color or black and white, and a visible light sensor 40 that detects the illuminance around the imaging unit 10, and when the imaging mode is day mode, if the gain value becomes equal to or greater than a predetermined value, the imaging mode is switched from day mode to night mode, and the illuminance around the imaging unit 10 at the time of this processing is detected. the detection result of the visible light sensor 40 at the time of the processing or the illuminance value calculated based on a virtual gain value, which is a virtual value of the gain value, is set as the switching threshold to be stored in the storage unit 62, when the imaging mode is the night mode, the imaging mode is switched from the night mode to the day mode when the detection result of the visible light sensor 40 is equal to or greater than the switching threshold stored in the storage unit 62, and when the imaging mode is the day mode and the processing for switching to the night mode is performed, the computer is caused to execute processing to set as the switching threshold to be stored in the storage unit 62 either the detection result of the visible light sensor 40 at the time of the processing or the illuminance value calculated based on a virtual gain value, which is a virtual value of the gain value, depending on the rate of change in the illuminance around the imaging unit.

[0074] According to this configuration, when the imaging mode is day mode and processing to switch to night mode is performed, the imaging mode can be appropriately switched when the illuminance around the imaging unit 10 changes suddenly by using either the detection result of the visible light sensor 40 at the time of the processing or the illuminance value calculated based on the virtual gain value, which is a virtual value of the gain value, as the switching threshold depending on the rate of change in the illuminance around the imaging unit.

[0075] In the imaging device 100 according to this embodiment, the control unit 60 determines whether the luminance value of the entire screen of the image signal output from the imaging unit 10 is equal to or greater than a specified value. If the luminance value of the entire screen is equal to or greater than the specified value, the detection result of the visible light sensor 40 at the time of processing to switch to night mode is used as the switching threshold. If the luminance value of the entire screen is below the specified value, the illuminance value calculated based on the virtual gain value is used as the switching threshold.

[0076] According to this configuration, it is possible to appropriately determine whether to use the detection result of the visible light sensor 40 at the time of the processing or the illuminance value calculated based on the virtual gain value, which is a virtual value of the gain value, as the switching threshold.

[0077] In the imaging device 100 according to this embodiment, the visible light sensor 40 detects illuminance at a predetermined cycle, and when the control unit 60 calculates the switching threshold based on the virtual gain value, the control unit 60 calculates the illuminance value that is the average value of the detection results of the visible light sensor 40 before and after the process of switching to night mode as the switching threshold.

[0078] According to this configuration, when the switching threshold is calculated based on the virtual gain value, the switching threshold can be calculated appropriately.

[0079] The technical scope of the present invention is not limited to the above-described embodiments, and appropriate modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0080] G1, G10, G2, G3, G4, G5, G6, G7, G8, G9, G10...graph, 10...imaging unit, 11...optical element, 12...infrared cut filter, 13...imaging element, 20...image signal processing unit, 21...AGC unit, 22...signal processing unit, 30...communication unit, 40...visible light sensor, 50...infrared light illumination unit, 60...control unit, 61...processing unit, 62...storage unit, 63...determination unit, 64...system control unit, 100...imaging device

Claims

1. an imaging unit capable of capturing images by switching the imaging mode between a day mode and a night mode; an image signal processing unit that adjusts a gain value so as to maintain a luminance value of an image signal output from the imaging unit within a certain range, and processes the color of the image signal to be color or black and white; a visible light sensor that detects the illuminance around the imaging unit; a control unit that, when the imaging mode is the day mode, performs a process of switching the imaging mode from the day mode to the night mode when the gain value becomes equal to or greater than a predetermined value, and stores an illuminance value around the imaging unit at the time of the process in a storage unit as a switching threshold, and, when the imaging mode is the night mode, performs a process of switching the imaging mode from the night mode to the day mode when the detection result of the visible light sensor becomes equal to or greater than the switching threshold stored in the storage unit; Equipped with When the control unit performs processing to switch the imaging mode to the night mode when the imaging mode is the day mode, the control unit determines, according to a change rate of illuminance around the imaging unit, either a detection result of the visible light sensor at the time of the processing or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value, as the switching threshold to be stored in the storage unit. Imaging device.

2. The control unit determines whether a luminance value of the entire screen of the image signal output from the imaging unit is equal to or greater than a specified value, and if the luminance value of the entire screen is equal to or greater than the specified value, sets the detection result of the visible light sensor at the time of the processing for switching to the night mode as the switching threshold value. If the luminance value of the entire screen is less than the specified value, sets the illuminance value calculated based on a virtual gain value as the switching threshold value. The imaging device according to claim 1 .

3. the visible light sensor detects the illuminance at a predetermined cycle; When calculating the switching threshold based on the virtual gain value, the control unit calculates, as the switching threshold, the illuminance value that is an average value of the detection results of the visible light sensor before and after the process of switching to the night mode. The imaging device according to claim 2 .

4. an imaging unit capable of capturing images by switching the imaging mode between a day mode and a night mode; an image signal processing unit that adjusts a gain value so as to maintain a luminance value of an image signal output from the imaging unit within a certain range, and processes the color of the image signal to be color or black and white; a visible light sensor that detects the illuminance around the imaging unit; A control method for an imaging device comprising: When the imaging mode is the day mode, a process of switching the imaging mode from the day mode to the night mode is performed when the gain value becomes equal to or greater than a predetermined value, and an illuminance value of the surroundings of the imaging unit at the time of the process is stored in a storage unit as a switching threshold value; When the imaging mode is the night mode, a process of switching the imaging mode from the night mode to the day mode is performed when a detection result of the visible light sensor becomes equal to or greater than the switching threshold value stored in the storage unit. When the imaging mode is the day mode and processing for switching to the night mode is performed, either the detection result of the visible light sensor at the time of the processing or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value is set as the switching threshold value to be stored in the storage unit, depending on a change rate of illuminance around the imaging unit. A method for controlling an imaging device.

5. an imaging unit capable of capturing images by switching the imaging mode between a day mode and a night mode; an image signal processing unit that adjusts a gain value so as to maintain a luminance value of an image signal output from the imaging unit within a certain range, and processes the color of the image signal to be color or black and white; a visible light sensor that detects the illuminance around the imaging unit; A control program for an imaging device comprising: When the imaging mode is the day mode, a process of switching the imaging mode from the day mode to the night mode when the gain value becomes equal to or greater than a predetermined value, and storing the illuminance value of the surroundings of the imaging unit at the time of the process in a storage unit as a switching threshold value; When the imaging mode is the night mode, a process of switching the imaging mode from the night mode to the day mode when the detection result of the visible light sensor becomes equal to or greater than the switching threshold value stored in the storage unit; a process of setting, when performing a process of switching to the night mode when the imaging mode is the day mode, either a detection result of the visible light sensor at the time of the process or the illuminance value calculated based on a virtual gain value that is a virtual value of the gain value as the switching threshold value to be stored in the storage unit, according to a change rate of illuminance around the imaging unit; A control program for an imaging device that causes a computer to execute the above.

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