Exposure control device, exposure control method, and exposure control program

Abstract

To provide an exposure control device which can set the appropriate exposure time for both the case of monitoring a periphery monitoring image and the case of using the periphery monitoring image for recognition and detection of a subject.SOLUTION: An exposure control device 40 includes a measurement information acquisition unit 44 and an exposure control unit 42. The measurement information acquisition unit 44 acquires the environment illuminance of a vehicle periphery measured by a measurement unit 19. The exposure control unit 42 controls the exposure time in an imaging unit 16 according to whether or not a periphery monitoring image captured by the imaging unit 16 that images the vehicle periphery is displayed on a display unit 20A when the environment illuminance acquired by the measurement information acquisition unit 44 is equal to or less than a predetermined prescribed value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, in driving assistance systems that display a vehicle's surroundings monitoring image on a monitor to assist the driver in maneuvering, such as pulling over or parking, while driving at low speeds, there has been a demand for improving the visibility of the displayed surroundings monitoring image by increasing the camera's exposure time, i.e., shutter speed, to brighten the entire image. On the other hand, in driving assistance systems that assist users using the results of subject recognition and detection processing by a camera, increasing the exposure time causes subject blur, known as "blur," in the captured image, reducing the recognition and detection rate. In particular, since blur tends to increase depending on the relative speed between the vehicle and the subject, there is a conflicting demand for a shorter exposure time when performing subject recognition and detection processing on images captured in low-light and high-speed areas. Patent Document 1 discloses a control device that shortens the exposure time of a Time of Flight (TOF) sensor and increases the emission intensity of the TOF sensor as the vehicle speed increases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-46162 Summary of the Invention [Problem to be solved by the invention]

[0004] When the same camera is used to capture surrounding monitoring images for video display and to capture images for recognizing and detecting objects, both functions are realized with the same exposure time setting, so optimal performance cannot be achieved for either function. In the control device for the TOF sensor described in Patent Document 1, the exposure time is shortened as the vehicle speed increases, but no consideration is given to a camera that performs two functions as described above.

[0005] In consideration of the above facts, the present invention aims to provide an exposure control device, an exposure control method, and an exposure control program that can set appropriate exposure times when monitoring surrounding monitoring images and when using surrounding monitoring images to recognize and detect subjects. [Means for solving the problem]

[0006] The exposure control device according to the present invention as set forth in claim 1 includes a measurement information acquisition unit that acquires an environmental illuminance around a vehicle measured by a measurement unit, and a display unit that displays a surrounding monitoring image captured by an image capture unit that captures an image of the surroundings of the vehicle when the environmental illuminance acquired by the measurement information acquisition unit is equal to or less than a predetermined value. and a case where the surroundings monitoring image is not displayed on the display unit and the recognition and detection system is made to recognize or detect the subject in the surroundings monitoring image. , the exposure time in the photographing unit Different and an exposure control unit.

[0007] According to the exposure control device of the present invention as set forth in claim 1, when the ambient illuminance is equal to or lower than a predetermined value, the exposure time of the photographing unit is set depending on whether or not to display on the display unit a surroundings monitoring image captured by the photographing unit that photographs the surroundings of the vehicle. Therefore, it is possible to set appropriate exposure times for both the case where the surroundings monitoring image is displayed on the display unit, i.e., when it is desired to monitor the surroundings monitoring image, and the case where the surroundings monitoring image is not displayed on the display unit, i.e., when it is desired to use the photographed image captured by the photographing unit for recognizing or detecting a subject.

[0008] The exposure control according to the present invention as set forth in claim 2 is the configuration as set forth in claim 1, wherein when the exposure control unit causes the display unit to display the surrounding monitoring image, the exposure time is a first exposure time derived based on the ambient illuminance, and when the display unit does not cause the surrounding monitoring image to be displayed, the exposure time is a second exposure time derived based on the ambient illuminance and the speed detected by a vehicle speed detection unit that detects the speed of the vehicle.

[0009] According to the exposure control device of the present invention recited in claim 2, the exposure control unit sets, as the exposure time, a first exposure time derived based on environmental illuminance when a periphery monitoring image is to be displayed on the display unit, and a second exposure time derived based on environmental illuminance and the vehicle speed when a periphery monitoring image is not to be displayed on the display unit. Therefore, when a periphery monitoring image is to be displayed on the display unit, for example, when an occupant wants to check the periphery of the vehicle when pulling over or parking, the first exposure time derived based on environmental illuminance is set in the imaging unit. This makes it possible to set the exposure time according to the environmental illuminance, thereby preventing an increase in noise due to a decrease in brightness.

[0010] Furthermore, when the surroundings monitoring image is not displayed on the display unit, for example, when it is desired to use the image captured by the image capturing unit for processing such as subject recognition or detection, the second exposure time derived based on the ambient illuminance and the vehicle speed is set in the image capturing unit. This makes it possible to set the exposure time according to the ambient illuminance and the vehicle speed, thereby preventing the occurrence of subject blur, which is known as "blur."

[0011] The exposure control device according to the present invention described in claim 3 has the configuration described in claim 2, wherein the exposure control unit sets the first exposure time to be longer than the second exposure time under a specified condition where at least the ambient illuminance and the speed are the same.

[0012] According to the exposure control device of the present invention described in claim 3, the exposure control unit sets the first exposure time longer than the second exposure time under predetermined conditions where at least the environmental illuminance and speed are the same. Therefore, when a surroundings monitoring image is displayed on the display unit, the exposure time is longer than when the surroundings monitoring image is not displayed, making it possible to brighten the entire surroundings monitoring image. Furthermore, when a surroundings monitoring image cannot be displayed on the display unit, the exposure time is shorter than when the surroundings monitoring image is displayed, making it possible to suppress the blurring that occurs when the exposure time is long. This makes it possible to prevent a decrease in subject recognition and detection rate.

[0013] The present invention according to claim 4 In the configuration described in any one of claims 1 to 3, the exposure control device allows the monitor to confirm the subject in the surrounding monitoring image when the vehicle is manually controlled by a user, and allows the recognition detection system to recognize or detect the subject in the surrounding monitoring image when the vehicle is automatically controlled by a driving assistance system. Claim 5 The exposure control method according to the present invention includes acquiring an environmental illuminance around a vehicle measured by a measurement unit, and displaying a surrounding monitoring image captured by an image capturing unit capturing an image of the surroundings of the vehicle on a display unit when the acquired environmental illuminance is equal to or less than a predetermined value. and a case where the surroundings monitoring image is not displayed on the display unit and the recognition and detection system is made to recognize or detect the subject in the surroundings monitoring image. , the exposure time in the photographing unit Different do.

[0014] Claim 5 According to the exposure control method of the present invention described in (1), when the ambient illuminance is equal to or lower than a predetermined value, the exposure time of the photographing unit is set depending on whether or not to display on the display unit a surroundings monitoring image captured by the photographing unit that photographs the surroundings of the vehicle. Therefore, it is possible to set appropriate exposure times for both the case where the surroundings monitoring image is displayed on the display unit, i.e., when it is desired to monitor the surroundings monitoring image, and the case where the surroundings monitoring image is not displayed on the display unit, i.e., when it is desired to use the photographed image captured by the photographing unit for recognizing or detecting a subject.

[0015] Claim 6 The exposure control program according to the present invention includes a measurement information acquisition unit that acquires the environmental illuminance around the vehicle measured by a measurement unit, and a measurement information acquisition unit that acquires the environmental illuminance around the vehicle measured by the measurement information acquisition unit. degreeIf the difference is equal to or less than a predetermined value, a surrounding monitoring image captured by a capturing unit capturing an image of the surroundings of the vehicle is displayed on a display unit. and a case where the surroundings monitoring image is not displayed on the display unit and the recognition and detection system is made to recognize or detect the subject in the surroundings monitoring image. , the exposure time in the photographing unit Different The computer functions as an exposure control unit.

[0016] Claim 6 According to the exposure control program of the present invention described in the above, when the ambient illuminance is equal to or lower than a predetermined value, the exposure time of the photographing unit is set depending on whether or not to display on the display unit a surroundings monitoring image captured by the photographing unit that captures the surroundings of the vehicle. Therefore, it is possible to set an appropriate exposure time for each of the cases where the surroundings monitoring image is displayed on the display unit, i.e., when it is desired to monitor the surroundings monitoring image, and the case where the surroundings monitoring image is not displayed on the display unit, i.e., when it is desired to use the captured image captured by the photographing unit for recognizing or detecting a subject. [Effects of the Invention]

[0017] As described above, the exposure control device, exposure control method, and exposure control program of the present invention have the excellent effect of being able to set appropriate exposure times for both cases where you want to monitor surrounding surveillance images and where you want to use captured images to recognize or detect subjects. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing a schematic configuration of a vehicle system including an exposure control device according to an embodiment of the present invention; [Figure 2] 4 is a flowchart showing an example of a series of processes of an exposure control device according to an embodiment of the present invention. [Figure 3] FIG. 10 is a diagram showing an example of a vehicle surroundings image when the exposure time is increased. [Figure 4] FIG. 10 is a diagram showing an example of a vehicle surroundings image when the exposure time is shortened. DETAILED DESCRIPTION OF THE INVENTION

[0019] A vehicle system 10 including a camera control device 40 according to one embodiment of the present invention will be described below with reference to the accompanying drawings. The vehicle system 10 of this embodiment is mounted on a vehicle (not shown), and as shown in Fig. 1, includes a vehicle control ECU (Electronic Control Unit) 12, an autonomous driving unit ADU (Autonomous Driving Unit) 14, and an on-board MM (multimedia) 20. The vehicle control ECU 12, the autonomous driving unit ADU 14, and the on-board MM 20 are connected to each other so as to be able to communicate with each other via a bus 22A configured, for example, by a CAN (Controller Area Network) signal line or the like.

[0020] The vehicle control ECU 12 is an ECU that performs overall control of the vehicle, and in this embodiment, performs automatic vehicle control by a driving assistance system and manual vehicle control by a user. The vehicle control ECU 12 includes a microcomputer (not shown), which includes a CPU, ROM, RAM, a readable / writable non-volatile memory, an interface, and the like. The CPU executes instructions (programs, routines) stored in the ROM to realize various functions. The vehicle control ECU 12 performs various controls in cooperation with other ECUs, such as an engine ECU, a brake ECU, and a camera ECU. The vehicle control ECU 12 is connected to a vehicle speed detection unit 18 that detects the vehicle speed and other sensor units (not shown), and is capable of acquiring vehicle speed information and vehicle status information, such as when the vehicle is moving or stopped.

[0021] The vehicle speed detection unit 18 detects the speed of the vehicle 100 (hereinafter, may be referred to as "vehicle speed V") and outputs a vehicle speed detection signal indicating the value of the vehicle speed V. The vehicle speed detection unit 18 is, for example, a vehicle speed sensor that detects the value of the vehicle speed V.

[0022] The autonomous driving unit ADU 14 assists autonomous driving and includes a microcomputer having a configuration similar to that of the vehicle control ECU 12. The autonomous driving unit ADU 14 includes a recognition detection system 30, an image display system 32, and a camera control device 40. The camera control device 40 of this embodiment also functions as an exposure control device.

[0023] The recognition and detection system 30 recognizes or detects a subject based on a surroundings monitoring image (captured image) acquired from the photographing unit 16 (described later) via the camera control unit 42 (described later). Examples of the subject include people, vehicles, guardrails, and other objects present around the vehicle. Note that known image processing can be used as a method for recognizing or detecting the subject from the surroundings monitoring image. Information about the recognized or detected subject is output to the vehicle control ECU 12.

[0024] The video display system 32 displays, on the display unit 20A, a periphery monitoring image (captured image) acquired from the image capturing unit 16, which will be described later, via the camera control unit 42, which will be described later. Specifically, the video display system 32 outputs the periphery monitoring image acquired by the camera control unit 42, which will be described later, to the in-vehicle MM 20. When the video display system 32 receives, from the camera control unit 42, a periphery monitoring image captured by each of the cameras 16A to 16D of the image capturing unit 16, the video display system 32 outputs the plurality of periphery monitoring images as they are to the in-vehicle MM 20, or performs image processing on the plurality of periphery monitoring images to generate display images such as panoramic images or bird's-eye images, and outputs the display images to the in-vehicle MM 20. Note that this image processing may be performed by the in-vehicle MM 20, rather than the video display system 32.

[0025] The video display system 32 outputs a surroundings monitoring image when there is a display request to the display unit 20A. Specifically, the video display system 32 determines that there is a display request to the display unit 20A when, for example, a display switch (not shown) provided near the steering wheel (not shown) is pressed by the occupant.

[0026] Furthermore, when the PVM (panoramic view monitor) is turned on in the autonomous driving unit ADU 14 and the vehicle speed V detected by the vehicle speed detection unit 18 via the vehicle control ECU 12 is equal to or less than a predetermined value, the video display system 32 determines that there is a display request for the display unit 20A. Here, the PVM is turned on and off by a PVM switch provided near the steering wheel (not shown), for example. On the other hand, when the PVM is turned off or when the vehicle speed V detected by the vehicle speed detection unit 18 exceeds the predetermined value, it is determined that there is no display request for the display unit 20A.

[0027] The camera control device 40 controls the image capturing unit 16 (described later) and includes a camera control unit 42 and a measurement information acquisition unit 44. The measurement unit 19 is connected to the measurement information acquisition unit 44, and the measurement unit 19 is configured with an illuminance sensor that measures the environmental illuminance around the vehicle. The measurement information acquisition unit 44 acquires the environmental illuminance around the vehicle measured by the measurement unit 19. Note that in this embodiment, the measurement unit 19 includes an illuminance sensor, but the present invention is not limited to this. For example, the measurement unit 19 may use the image capturing unit 16 as an illuminance sensor instead of an illuminance sensor. That is, the captured image acquired by the image capturing unit 16 contains information on the environmental illuminance. Therefore, the environmental illuminance may be estimated by performing arithmetic processing on the acquired captured image. Specifically, the environmental illuminance may be estimated by averaging multiple pixel values ​​included in the captured image, as an example.

[0028] The camera control unit 42 controls the image capturing unit 16 and is connected to the image capturing unit 16. The image capturing unit 16 is a camera that captures the surroundings of the vehicle and includes multiple cameras, such as color CCD (Charge Coupled Device) cameras. In this embodiment, the image capturing unit 16 includes a front camera 16A that captures the area in front of the vehicle, a right side camera 16B that captures the area to the right of the vehicle, a left side camera 16C that captures the area to the left of the vehicle, and a rear camera 16D that captures the area to the rear of the vehicle. The front camera 16A and the rear camera 16D are installed in the center of the vehicle width direction on the inside or outside of the front and rear of the vehicle, respectively. The right side camera 16B and the left side camera 16C are installed on the side mirrors on the right and left sides of the vehicle, respectively. The image capturing unit 16 captures the surroundings of the vehicle and outputs the captured vehicle surroundings images to the camera control unit 42. Note that the "vehicle surroundings images" may be video data or still image data.

[0029] The camera control unit 42 supplies power to the photographing unit 16, and causes the photographing unit 16 to photograph surrounding images under preset photographing conditions, thereby acquiring the photographed images photographed by the photographing unit 16 as surrounding monitoring images. In this embodiment, the camera control unit 42 also functions as an exposure control unit that controls the exposure time in the photographing unit 16.

[0030] When the environmental illuminance around the vehicle acquired by the measurement information acquisition unit 44 is equal to or lower than a predetermined value, the camera control unit 42 controls the exposure time of the image capturing unit 16 depending on whether or not the surroundings monitoring image captured by the image capturing unit 16 is to be displayed on the display unit 20A. In other words, the camera control unit 42 controls the exposure time of the image capturing unit 16 depending on whether or not the video display system 32 has determined that there is a display request on the display unit 20A.

[0031] Specifically, when the video display system 32 causes the display unit 20A to display a surroundings monitoring image, the camera control unit 42 sets the first exposure time Tm derived based on the ambient illuminance as the exposure time in the photographing unit 16. When the video display system 32 does not cause the display unit 20A to display a surroundings monitoring image, the camera control unit 42 sets the second exposure time Ta derived based on the ambient illuminance and the vehicle speed V as the exposure time in the photographing unit 16.

[0032] Here, the camera control unit 42 determines in advance the brightness (values ​​of illuminance, luminance, etc.) of the entire image that will allow a monitor (passenger) monitoring the surroundings monitoring image to easily identify a subject in the surroundings monitoring image with the naked eye when the surroundings monitoring image is displayed on the display unit 20A. The camera control unit 42 then derives in advance the relationship between the value of the environmental illuminance around the vehicle required to ensure this brightness and the exposure time, and determines the first exposure time Tm by deriving the exposure time from the environmental illuminance acquired by the measurement information acquisition unit 44 based on this relationship.

[0033] Furthermore, the camera control unit 42 determines in advance the brightness (values ​​of illuminance, luminance, etc.) of the entire image that will result in the highest recognition or detection rate when the recognition and detection system 30 recognizes or detects a subject from a surrounding monitoring image. The camera control unit 42 then derives in advance the relationship between the environmental illuminance value around the vehicle and the vehicle speed V required to ensure this brightness, and the exposure time, and determines the second exposure time Ta by deriving the exposure time from the environmental illuminance acquired by the measurement information acquisition unit 44 and the vehicle speed V detected by the vehicle speed detection unit 18 based on this relationship.

[0034] The first exposure time Tm and the second exposure time Ta are set so that the first exposure time Tm is longer than the second exposure time Ta, i.e., Tm>Ta, under a predetermined condition where at least the ambient illuminance and the vehicle speed V are the same.

[0035] The in-vehicle MM 20 displays images on a display unit 20A configured as a monitor and outputs audio through a speaker. The display unit 20A is, for example, a monitor that is easily visible to occupants such as the driver and front passenger, and is specifically provided on an instrument panel or meter panel, and displays, in addition to a surrounding monitoring image, images suggesting operation of vehicle functions and images explaining various functions. The display unit 20A also functions as a touch panel that also serves as an input switch. However, the display unit 20A is not limited to this and may be configured as a projection surface onto which an image is projected by a head-up display device (not shown).

[0036] The in-vehicle MM 20 receives signals from other devices such as the video display system 32, the autonomous driving unit ADU 14, and the vehicle control ECU 12, performs image processing as necessary, and displays the image on the display unit 20A. In this embodiment, the in-vehicle MM 20 displays the surroundings monitoring image received from the video display system 32 or the processed surroundings monitoring image on the display unit 20A.

[0037] Next, a series of processes executed in the autonomous driving unit ADU 14 including the vehicle camera control device 14 will be described using the flowchart shown in Figure 2. The processes executed in the autonomous driving unit ADU 14 are executed by the CPU of the autonomous driving unit ADU 14 reading a program from ROM or storage, expanding it into RAM, and executing it. The program includes an exposure control program.

[0038] 2, first, in step S11, the CPU of the autonomous driving unit ADU 14 confirms that the power of the image capturing unit 16 has been turned on. In this embodiment, the power of the image capturing unit 16 is turned on when the vehicle is started. Next, in step S12, the measurement information acquisition unit 44 acquires the ambient illuminance measured by the measurement unit 19. Next, in step S13, the CPU of the autonomous driving unit ADU 14 determines the vehicle control state, based on a signal from the vehicle control ECU 12, whether the vehicle is being automatically controlled by a driving assistance system or manually controlled by a user.

[0039] In the case of automatic vehicle control (step S13; automatic), in step S15, the camera control unit 42 acquires the vehicle speed V detected by the vehicle speed detection unit 18 via the vehicle control ECU 12 as vehicle speed information. Next, in step S16, the camera control unit 42 derives a second exposure time Ta according to the vehicle speed V and the ambient illuminance. Then, in step S17, the camera control unit 42 determines that the surroundings monitoring image captured by the image capture unit 16 is an image that prioritizes subject recognition and detection, and sets the second exposure time Ta derived in step S16 as the exposure time Ta for the image capture unit 16.

[0040] In step S18, the recognition and detection system 30 performs subject recognition and detection processing on the surroundings monitoring image captured by the image capture unit 16 with the exposure time Ta. The processing results by the recognition and detection system 30 are output to the vehicle control ECU 12 via the bus 22A, and the vehicle control ECU 12 performs automatic vehicle control based on the processing results output by the recognition and detection system 30. During automatic vehicle control by the vehicle control ECU 12, for example, when the vehicle performs an operation such as parking or pulling over, the surroundings monitoring image captured by the image capture unit 16 with the exposure time Ta may be displayed on the display unit 20A by the video display system 32.

[0041] On the other hand, if the CPU of the autonomous driving unit ADU 14 determines in step S13 that the vehicle is being manually controlled by the user (step S13; manual), then in step S14 the video display system 32 determines whether or not there is a display request for the display unit 20A. If there is no display request (step S13; NO), the CPU of the autonomous driving unit ADU 14 proceeds to step S15 and performs the processes from step S15 onwards.

[0042] Furthermore, if the video display system 32 determines in step S14 that there is a display request on the display unit 20A (step S14; YES), the camera control unit 42 derives a first exposure time Tm according to the ambient illuminance in step S19. Then, in step S20, the camera control unit 42 determines that the surrounding monitoring image captured by the imaging unit 16 is an image for which video display is prioritized, and sets the first exposure time Tm derived in step S19 as the exposure time Tm for the imaging unit 16.

[0043] Next, in step S21, the video display system 32 performs video display processing to process the multiple surroundings monitoring images captured by the cameras 16A to 16D of the imaging unit 16, each with an exposure time Tm, into a format for display on the display unit 20A and output the processed images to the in-vehicle MM 20. The in-vehicle MM 20 displays the surroundings monitoring images output by the video display system 32 on the display unit 20A.

[0044] Next, in step S22, the CPU of the automatic driving unit ADU 14 determines whether or not to end the series of processes. If not (step S22; NO), the process proceeds to step S12, and the processes from step S12 onward are continued. If, in step S22, the series of processes are to be ended (step S22; YES), the CPU of the automatic driving unit ADU 14 ends all processes. Note that in this embodiment, as an example, the CPU of the automatic driving unit ADU 14 determines that an end instruction has been issued when, for example, the vehicle is stopped (the engine is stopped or the drive motor is stopped), or when a display end instruction is issued by the user through a switch (not shown) operation, voice, or the like.

[0045] Next, the effects of this embodiment will be described.

[0046] According to the camera control device 40 serving as an exposure control device of this embodiment, when the ambient illuminance is equal to or lower than a predetermined value, the exposure time in the image capturing unit 16 is set depending on whether or not to display on the display unit 20A a surroundings monitoring image captured by the image capturing unit 16 that captures the surroundings of the vehicle. Therefore, an appropriate exposure time can be set for each of the cases where the surroundings monitoring image is displayed on the display unit 20A, i.e., when it is desired to monitor the surroundings monitoring image, and where the surroundings monitoring image is not displayed on the display unit 20A, i.e., when it is desired to use the surroundings monitoring image (captured image) captured by the image capturing unit 16 for recognizing or detecting a subject.

[0047] Fig. 3 shows an example of an image of the vehicle's surroundings when the exposure time is longer than that of Fig. 4, and Fig. 4 shows an example of an image of the vehicle's surroundings when the exposure time is shorter than that of Fig. 3. When assisting with operations such as pulling over to the side of the vehicle when traveling at low speeds or parking by displaying a monitoring image of the vehicle's surroundings on display unit 20A, there is a demand for improving the visibility of the displayed monitoring image of the surroundings by lengthening the exposure time of imaging unit 16 and brightening the entire image.

[0048] On the other hand, when the vehicle control ECU 12 performs automatic vehicle control using the results of the subject recognition and detection process by the image capture unit 16, if the exposure time of the image capture unit 16 is extended, blurring of the subject, known as "blur," occurs in the captured image, as shown in Fig. 3, resulting in a decrease in the recognition and detection rate. In particular, since the occurrence of blur tends to increase depending on the relative speed between the vehicle and the subject, there is a demand for a shorter exposure time when performing subject recognition and detection process on captured images captured in low-light and high-speed areas.

[0049] On the other hand, when assisting with operations such as pulling over to the side of the vehicle or parking while traveling at low speed by displaying a vehicle periphery monitoring image on the display unit 20A, shortening the exposure time of the image capturing unit 16 reduces the brightness of the entire image. Therefore, adjusting the brightness by, for example, gain increases noise, as shown in FIG.

[0050] Therefore, according to the camera control device 40 serving as an exposure control device of this embodiment, the camera control unit 42 serving as an exposure control unit sets, as the exposure time, a first exposure time Tm derived based on the ambient illuminance when a periphery monitoring image is to be displayed on the display unit 20A, and a second exposure time Ta derived based on the ambient illuminance and the vehicle speed, i.e., vehicle speed V, when a periphery monitoring image is not to be displayed on the display unit 20A. Therefore, when a periphery monitoring image is to be displayed on the display unit 20A, for example, when an occupant wants to check the periphery of the vehicle when pulling over or parking while traveling at low speed, the first exposure time Tm derived based on the ambient illuminance is set in the imaging unit 16. This makes it possible to set the exposure time according to the ambient illuminance, thereby preventing an increase in noise due to a decrease in brightness.

[0051] Furthermore, when the surroundings monitoring image (photographed image) by the photographing unit 16 is to be used for processing such as subject recognition and detection, for example, and the surroundings monitoring image is not to be displayed on the display unit 20A, a second exposure time is set that is derived based on the ambient illuminance and the vehicle speed V. This makes it possible to set the exposure time according to the ambient illuminance and the vehicle speed V, thereby preventing the occurrence of subject blurring, which is known as "blur."

[0052] Furthermore, according to the camera control device 40 serving as an exposure control device of this embodiment, the camera control unit 42 serving as an exposure control unit sets the first exposure time Tm to be longer than the second exposure time Ta, at least under a predetermined condition where the ambient illuminance and vehicle speed V are the same. Therefore, when a periphery monitoring image is displayed on the display unit 20A, the exposure time is longer than when the periphery monitoring image is not displayed, thereby making it possible to brighten the entire periphery monitoring image. Furthermore, when a periphery monitoring image cannot be displayed on the display unit 20A, the exposure time is shorter than when the periphery monitoring image is displayed, thereby suppressing the blurring that occurs when the exposure time is long. This prevents a decrease in subject recognition and detection rate.

[0053] Furthermore, according to the exposure control method of this embodiment, when the ambient illuminance is equal to or lower than a predetermined value, the exposure time in the photographing unit 16 is set depending on whether or not to display on the display unit 20A a surroundings monitoring image captured by the photographing unit 16 that captures the surroundings of the vehicle. Therefore, an appropriate exposure time can be set for each of the cases where the surroundings monitoring image is displayed on the display unit 20A, i.e., when it is desired to monitor the surroundings monitoring image, and where the surroundings monitoring image is not displayed on the display unit 20A, i.e., when it is desired to use the surroundings monitoring image (captured image) captured by the photographing unit 16 for recognizing or detecting a subject.

[0054] Furthermore, according to the exposure control program of this embodiment, when the ambient illuminance is equal to or lower than a predetermined value, the exposure time in the photographing unit 16 is set depending on whether or not to display on the display unit 20A a surroundings monitoring image captured by the photographing unit 16 that captures the surroundings of the vehicle. Therefore, an appropriate exposure time can be set for each of the cases where the surroundings monitoring image is displayed on the display unit 20A, i.e., when it is desired to monitor the surroundings monitoring image, and where the surroundings monitoring image is not displayed on the display unit 20A, i.e., when it is desired to use the surroundings monitoring image (captured image) captured by the photographing unit 16 for recognizing or detecting a subject.

[0055] In the above embodiment, the camera control device 40 as an exposure control device is mounted on a vehicle as an example of a vehicle, but the present invention is not limited to vehicles. For example, the exposure control device of the present invention may be mounted on a vehicle such as a ship or an airplane.

[0056] In the above embodiment, the image capturing unit 16 includes four cameras, namely, the front camera 16A, the right side camera 16B, the left side camera 16C, and the rear camera 16D, but the present invention is not limited to this. As long as the image capturing unit 16 is configured to capture images of the periphery of the vehicle, the number of cameras may be more than four, or a 360° camera may be used, and other suitable modifications may be made.

[0057] In addition, in the above embodiment, the processing performed by each part of the vehicle control ECU 12 and the autonomous driving unit ADU 14 has been described as software processing performed by executing a program, but this is not limited to this. For example, the processing may be performed by hardware. Alternatively, the processing may be a combination of both software and hardware. Furthermore, if the processing is software, the program may be stored in various storage media and distributed. Furthermore, the program may be downloaded from an external device via a network.

[0058] Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment may be appropriately combined with various modified examples, and the present invention may of course be embodied in various forms as long as it does not deviate from the gist of the present invention. [Explanation of symbols]

[0059] 16 Photography Department 18 Vehicle speed detection unit 19 Measurement section 40 Camera control device (exposure control device) 42 Camera control unit (exposure control unit) 44 Measurement information acquisition unit Tm First exposure time Ta Second exposure time

Claims

1. a measurement information acquisition unit that acquires the environmental illuminance around the vehicle measured by the measurement unit; an exposure control unit that, when the environmental illuminance acquired by the measurement information acquisition unit is equal to or lower than a predetermined value, causes a surroundings monitoring image captured by an image capturing unit that captures images of the surroundings of the vehicle to be displayed on a display unit so that a monitor can check the subject in the surroundings monitoring image, and causes a recognition detection system to recognize or detect the subject in the surroundings monitoring image without displaying the surroundings monitoring image on the display unit; and An exposure control device including:

2. The exposure control unit When the surroundings monitoring image is displayed on the display unit, a first exposure time derived based on the environmental illuminance is set as the exposure time; 2. The exposure control device according to claim 1, wherein when the surrounding monitoring image is not displayed on the display unit, the exposure time is set to a second exposure time derived based on the ambient illuminance and the speed detected by a vehicle speed detection unit that detects the speed of the vehicle.

3. 3. The exposure control device according to claim 2, wherein the exposure control unit sets the first exposure time to be longer than the second exposure time under a predetermined condition where at least the environmental illuminance and the speed are the same.

4. An exposure control device as described in claim 1, which allows the monitor to confirm the subject in the surrounding monitoring image when the vehicle is manually controlled by a user, and allows the recognition detection system to recognize or detect the subject in the surrounding monitoring image when the vehicle is automatically controlled by a driving assistance system.

5. The environmental illuminance around the vehicle measured by the measurement unit is acquired, An exposure control method in which, when the acquired ambient illuminance is equal to or lower than a predetermined value, the exposure time in the photographing unit is made different between a case in which a surrounding monitoring image captured by the photographing unit that photographs the area around the vehicle is displayed on a display unit to allow a monitor to check the subject in the surrounding monitoring image, and a case in which the surrounding monitoring image is not displayed on the display unit and the recognition detection system is allowed to recognize or detect the subject in the surrounding monitoring image.

6. a measurement information acquisition unit that acquires the environmental illuminance around the vehicle measured by the measurement unit; When the environmental illuminance acquired by the measurement information acquisition unit is equal to or less than a predetermined value, an exposure control unit that makes different exposure times in the image capture unit between a case where a surrounding monitoring image captured by an image capture unit that captures the surroundings of the vehicle is displayed on a display unit to allow a monitor to check a subject in the surrounding monitoring image, and a case where the surrounding monitoring image is not displayed on the display unit and a recognition detection system is allowed to recognize or detect a subject in the surrounding monitoring image, The exposure control program that makes the computer work.

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