JP2009267923A - Imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging system that suppresses unbalance of brightness at a boundary of each camera image frame without adding any new component and even if the cameras have variation in performance. <P>SOLUTION: The cameras 10A to 10D each are provided with a video processing circuit 13 which provides a common imaging area to be shared with other cameras in an imaging area to be photographed and detects a luminance signal of the common imaging area to generate common area exposure detection information. A central controller 30 has a central processor 33 which compares pieces of common area exposure detection information sent from the respective cameras and outputs exposure correction information 23 to corresponding cameras according to differences of common area exposure detection information in the same common imaging area between the cameras. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging system that synthesizes and displays images obtained from a plurality of cameras, and more particularly to an imaging system that eliminates the brightness imbalance that occurs at the image boundary from each camera.

  2. Description of the Related Art An imaging system has been put into practical use in which a camera is installed on an automobile body, a driver's blind spot image is displayed by imaging a vehicle periphery, and a driving assistance function is provided. The original in-vehicle imaging system is mainly one in which one camera is installed on the rear side of the vehicle or on the side opposite to the driver's seat and the captured image of the camera is displayed on the display monitor as it is. Recently, four or more cameras are arranged around the vehicle, and using viewpoint conversion technology or the like, for example, a viewpoint image from the top of the vehicle is generated in a pseudo manner, and each camera image is synthesized, It is possible to monitor the surroundings. A technique for imaging the surroundings of the vehicle and providing parking assistance to the user is disclosed in, for example, Patent Documents 1 and 2.

Japanese Patent Application Laid-Open No. 2005-239048 JP 2008-44529 A

  Generally, a camera has an automatic exposure control function that controls the brightness signal amount to an appropriate value by adjusting the aperture and electronic shutter speed according to the luminance signal amount of the photographed image, and the ratio of the red component to the blue component of the photographed image. An automatic color balance control function or an automatic color temperature correction function for estimating the subject color temperature from the above and maintaining the white balance appropriately is implemented. That is, the images output by the individual cameras for various subjects can maintain an appropriate luminance signal amount and color balance with respect to the images within the imaging frames captured by the respective cameras. However, due to these automatic control functions, when images from a plurality of cameras are combined to synthesize one image, there is a problem that unbalance in brightness and hue occurs at the boundaries of the image frames of the cameras.

The mechanism of occurrence of this imbalance will be described with reference to the drawings.
FIG. 3 shows an example in which four cameras are installed on the front, rear, left and right sides of the vehicle, and an image from a viewpoint above the vehicle is artificially synthesized and displayed using the viewpoint conversion technology disclosed in the patent document. is there. As shown in (a), cameras A, B, C, and D are arranged on the front, rear, left and right sides of the vehicle. (B) is a display image, and the images captured by the respective cameras are output to the areas A, B, C, and D of the display screen, respectively, and an entire image is generated. Here, it is assumed that the front of the vehicle (upward in the drawing) is sunny and the rear of the vehicle (downward in the drawing) is shaded. Originally, as shown in (b), the area A should be bright, the area D should be dark, and the brightness should be displayed at the same level at the boundaries of the areas A, B, C, and D. However, in the actual display image after synthesis, as shown in (c), the brightness is unbalanced at the boundary of each region.

  This is because each camera independently performs automatic exposure control based on an image within an imaging frame to be photographed. Each camera is controlled by automatic exposure control so that the total amount of luminance signals obtained in the imaging frame is maintained at a constant value. Therefore, for example, when comparing camera A and camera D, exposure is performed so that the image of camera A that captures the sunlit portion is darker than the original, and the image of camera D that captures the shaded portion is brighter than the original. Displayed. The images of the camera B and the camera C include both a sunlit portion and a shaded portion, but if the occupation ratio is different, the exposure condition is different for the same reason, so that the brightness is unbalanced at the boundary of each region. Will occur.

  In order to eliminate this unbalance, for example, (1) a method in which an illuminance sensor is installed at the installation position of each camera, and the exposure condition of each camera is controlled according to the illuminance value at each position, and (2) each camera It is conceivable to take measures such as a method for controlling each camera so that the same exposure condition (aperture value or shutter speed) is obtained from the central control device that performs the synthesis processing of the above signals. However, in (1), it is necessary to attach a new sensor component, and in (2), it is required that a plurality of cameras (imaging devices) exhibit the same performance (photosensitivity characteristics). It can not be said.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an imaging that can suppress brightness imbalance at the boundary of each camera image frame without adding new parts and even if the performance of the camera varies. Is to provide a system.

  The present invention is an imaging system that transmits images captured by a plurality of cameras to a central control device and combines and displays images from the cameras, and each camera is connected to another camera in an imaging area to be captured. Providing a common imaging area that is an area shared between the two, a video processing circuit that processes the captured image signal and detects the luminance signal of the common imaging area part to generate common area exposure detection information, and the captured image signal And a transmission processing circuit for transmitting the common area exposure detection information to the central control device, and a camera processor for outputting an exposure control signal to the optical system and the image sensor. The central control device transmits the image signal transmitted from each camera. Is compared with the display processing unit that displays the image on the image display unit and the common area exposure detection information transmitted from each camera. A central processor for outputting exposure correction information to the corresponding camera in accordance with the difference between the information of the camera.

  Here, when the difference between the common area exposure detection information of the two cameras in the same common imaging area is larger than a predetermined threshold, the central processor of the central control unit needs an exposure correction amount necessary based on the difference of the common area exposure detection information. And the exposure correction information is output to one camera.

  In addition, the video processing circuit of each camera has a function of performing non-linear luminance gradation correction on the captured image signal, and the central processor of the central control device determines the luminance gradation of the transmitted image signal according to the luminance gradation of the transmitted image signal. The luminance gradation correction operation is controlled for the video processing circuit of the corresponding camera.

  According to the present invention, it is possible to provide a practical imaging system that suppresses brightness imbalance at the boundary of each camera image frame without adding new parts and even if the performance of the camera varies.

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

FIG. 1 is a system configuration diagram showing an embodiment of an imaging system of the present invention.
In the imaging system of this embodiment, four cameras A, B, C, and D (reference numerals 10A, 10B, 10C, and 10D) are installed on the front, rear, left, and right sides of the vehicle, and image signals from the cameras are transmitted via the transmission path 20. Thus, the image is transmitted to the central control device 30, and a composite image from a viewpoint above the vehicle is generated and displayed on the image display unit 40.

  In each of the cameras 10 </ b> A to 10 </ b> D, an image formed on the image sensor 12 from the optical system 11 is processed by the image processing circuit 13 and the transmission processing circuit 15. The video processing circuit 13 outputs exposure detection information 14 used for exposure control to a processor (camera processor) 17. The exposure detection information 14 is information obtained by detecting the luminance signal in the captured image, and is information such as the sum value, average value, maximum value, minimum value, and luminance distribution histogram of the luminance signal. The exposure detection information 14 includes a case where the entire captured image is detected as a single area, and a case where the captured image is divided into a plurality of areas and the luminance signal of each area is detected.

  The processor 17 outputs an exposure control command 19 to the optical system 11 and the image sensor 12 so as to maintain an appropriate exposure state based on the exposure detection information 14. This command instructs the optical system 11 to update the aperture value, and instructs the image sensor 12 to update the shutter speed. Further, the processor 17 outputs a gradation correction command 18 to the video processing circuit 13. This gradation correction is a level correction for displaying an image with a more natural brightness when the image is actually output and displayed.

  The video processing circuit 13 further detects exposure signal of a specific area (common imaging area to be described later) in the captured image to generate exposure detection information. The transmission processing circuit 15 outputs exposure detection information (hereinafter, common area exposure detection information) 22 of the common imaging area together with the image signal 21 from the cameras 10 </ b> A to 10 </ b> D toward the transmission path 20.

  In the central controller 30, the image signal 21 of each camera input from the transmission path 20 via the transmission processing circuit 31 is temporarily stored in the memory 32. The display processing circuit 34 performs viewpoint conversion processing, image synthesis processing, and the like on the image from each camera, generates a composite image, and outputs the composite image to the image display unit 40.

  In the central controller 30, the processor (central processor) 33 compares and evaluates the common area exposure detection information 22 input from the transmission path 20. If there is a difference between the cameras in the common area exposure detection information 22, the processor 33 generates the exposure correction information 23 for each camera so as to reduce the difference. The generated exposure correction information 23 is transmitted to each camera via the transmission processing circuit 31 and the transmission path 20. Each camera receives exposure correction information 23 via the transmission processing circuit 15, sends exposure correction information 16 to the processor 17, and outputs an exposure correction command 19 to the optical system 11 and the image sensor 12.

  As described above, the present embodiment is characterized in that a common imaging area is provided for the captured image of each camera, exposure detection information in the area is compared, and the exposure condition of each camera is corrected so as to reduce the difference. To do. As a result, the luminance values of the common imaging areas can be matched, and the brightness imbalance at the boundaries of the camera image frames can be eliminated.

  FIG. 2 is a diagram illustrating a common imaging area provided in each camera in the present embodiment.

  Each of the cameras 10A to 10D shoots the imaging areas A to D, respectively, but covers a wider area than the display area that is finally used for display. In each of the imaging areas A to D, an area shared with the imaging areas of other adjacent cameras, that is, a common imaging area is provided. For example, a common imaging area for the imaging area A and the imaging area B is indicated by a symbol Sab (shaded portion). In this embodiment, four common imaging areas Sab, Sac, Sbd, and Scd are provided for four imaging areas.

  The video processing circuit 13 of each camera detects luminance signals in the common imaging areas Sab, Sac, Sbd, and Scd, and outputs the detected luminance signals to the central controller 30 as common area exposure detection information 22. For example, for the common imaging area Sab, common area exposure detection information Iab (A) belonging to the imaging area A and common area exposure detection information Iab (B) belonging to the imaging area B are output. The central control unit 30 compares them and generates exposure correction information 23 for the camera A or B so that the difference is reduced.

The principle of exposure correction according to this embodiment will be described with reference to FIG.
For example, it is assumed that the above-described imbalance as shown in FIG. In the common imaging area Sab, the common area exposure detection information Iab (A) has a luminance value smaller (darker) than the common area exposure detection information Iab (B), so that the exposure condition of the camera A is corrected to be brighter ( Correction A ′). Further, in the common imaging area Sbd, the common area exposure detection information Ibd (D) has a luminance value larger (brighter) than the common area exposure detection information Ibd (B), so that the exposure condition of the camera D is corrected to be darker. (Correction D ′). For the other common imaging areas Sac and Scd, the exposure conditions are corrected by comparing the respective common area exposure detection information. As a result, as shown in FIG. 3B, it is possible to display a composite image having no brightness imbalance at the boundary of each region.

  According to the exposure correction of this embodiment, it is not necessary to add a new sensor component for correction. Further, even when the performance (photosensitivity characteristics) of a plurality of cameras (imaging devices) to be installed varies, it is possible to suppress the occurrence of brightness imbalance at the boundary between the regions. Therefore, a practical imaging system is provided.

Next, an exposure correction algorithm performed by the processor 33 of the central controller 30 will be described.
In each common imaging area Sab, Sac, Sbd, Scd, the common area exposure detection information from two cameras is compared. As a result of the comparison, if the difference between the two is larger than a predetermined threshold value, exposure correction information 23 for correcting the exposure condition of one camera is issued. When the difference between the two is within the threshold value, the exposure condition is not corrected. Then, the exposure detection information in each of the common imaging areas Sab, Sac, Sbd, and Scd after the exposure condition correction is compared again and adjusted so that the difference is within the threshold. As a result, exposure detection information can be matched in all common imaging areas.

  FIG. 4 is a diagram showing a general flowchart of the exposure correction process of the present embodiment.

  In step S401, exposure detection information Iab (A), Iab (B),... Of each camera image in each common imaging area Sab, Sac, Sbd, Scd is acquired. In step S402, the magnitude relationship of each common area exposure detection information is examined to determine a correction reference camera. The correction reference camera is a camera that is used as a reference for setting exposure conditions. For example, it is preferable to select a camera having the maximum luminance distribution (difference in exposure detection information) in the camera image. For example, in the case of FIG. 3, the camera B (or C) may be used as the correction reference camera. In step S403, a correction target camera to be subjected to exposure correction is determined. The correction target camera is a camera other than the correction reference camera, and in the case of FIG. 3, cameras A, C (or B), and D correspond.

  In step S404, an exposure deviation amount is calculated for one correction target camera. For example, for the camera A, the amount of exposure deviation is obtained by taking the difference of the common area exposure detection information with the camera B. In step S405, it is determined whether the exposure deviation amount is within a threshold value. If it is within the threshold value, it is determined that correction is unnecessary, and the process proceeds to step S408.

  In step S406, an exposure correction amount is calculated for the correction target camera by multiplying the exposure deviation amount by a conversion coefficient. In step S407, the exposure balance point is corrected so as to shift by the exposure correction amount with respect to the correction target camera. Returning to step S405, it is determined whether the exposure deviation amount is within the threshold as a result of exposure correction. If it is larger than the threshold value, the process proceeds to step S406 and correction is performed again.

  In step S408, it is determined whether other correction target cameras remain. For example, in the case of FIG. 3, since the cameras C and D remain, the process returns to step S604 and exposure correction is similarly performed.

  With the above processing flow, exposure detection information can be matched in all common imaging areas. In steps S402 and S403, the correction reference camera and the correction target camera can be arbitrarily selected, and the number of cameras can be arbitrarily set. Thereby, exposure correction can be efficiently performed according to an actual display image.

  FIG. 5 is a diagram illustrating a representative example of exposure correction of a composite image. Here, examples of unbalanced images generated due to the direction of the sun (shade) are divided into cases 1 to 6. Due to the direction of the sun, a difference (a difference larger than a threshold value) occurs in each common area exposure detection information in the common imaging areas Sab, Sac, Sbd, and Scd. The magnitude relationship between the common area exposure detection information Iab (A), Iab (B),... Is as described in the table in the figure. However, for the sake of simplicity, the difference in brightness at the camera boundary is not expressed in the display screen.

  Cases 1 to 4 are cases in which a difference occurs in the common area exposure detection information in all (four places) common imaging areas Sab, Sac, Sbd, and Scd. Case 5 is a case where a difference occurs in the common area exposure detection information in the three common imaging areas Sac, Sbd, and Scd. Case 6 is a case where a difference occurs in the common area exposure detection information in the two common imaging areas Sbd and Scd. Case 5 and case 6 are shown only when the sun (shade) direction is an example. Although not shown, there may be a difference in the common area exposure detection information only in one common imaging area.

  The exposure correction is preferably executed when a difference occurs in the common area exposure detection information in any one or more common imaging areas. However, as in cases 1 to 4, all (4 locations) common imaging areas are used. It may be executed only when a difference occurs in the common area exposure detection information in Sab, Sac, Sbd, and Scd.

The exposure correction method for each case outputs the following exposure correction information to the corresponding camera.
In case 1, the exposure balance point E (A) for the camera A is shifted in the direction of increasing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera B or camera C.

For this purpose, first, an exposure deviation amount of the camera A is calculated. The exposure deviation amount ΔI (A) is an average of the difference between the common imaging area Sab and the camera B and the common imaging area Sac.
ΔI (A) = [{Iab (B) −Iab (A)}
+ {Iac (C) -Iac (A)}] / 2 (1)
Next, in order to reduce the exposure deviation amount ΔI (A), the exposure correction amount ΔE (A) for the camera A is calculated by multiplying by the conversion coefficient k.
ΔE (A) = k · ΔI (A) (2)
Accordingly, the exposure balance point E (A) is corrected in the direction of increasing the brightness by the above-described ΔE (A) with respect to the camera A.

Further, the exposure balance point E (D) with respect to the camera D is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera B or the camera C. The correction amount in this case is obtained by the following calculation.
ΔI (D) = [{Ibd (D) −Ibd (B)}
+ {Icd (D) -Icd (B)}] / 2 (3)
ΔE (D) = k · ΔI (D) (4)
Thus, the exposure balance point E (D) is corrected with respect to the camera D in the direction of reducing the brightness by the ΔE (D).

The other cases are as follows. Each calculation formula is omitted.
In case 2, the exposure balance point E (A) for the camera A is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera B or camera C. Further, the exposure balance point E (D) with respect to the camera D is shifted in the direction in which the brightness is increased by an amount corresponding to the difference in the common area exposure detection information with the camera B or the camera C.

  In case 3, the exposure balance point E (B) for the camera B is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera A or camera D. Further, the exposure balance point E (C) for the camera C is shifted in the direction of increasing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera A or the camera D.

  In case 4, the exposure balance point E (B) for the camera B is shifted in the direction of increasing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera A or camera D. Further, the exposure balance point E (C) for the camera C is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera A or the camera D.

  In case 5, the exposure balance point E (C) for the camera C is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera A. Further, the exposure balance point E (D) for the camera D is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera B.

In case 6, the exposure balance point E (D) for the camera D is shifted in the direction of reducing the brightness by the amount corresponding to the difference in the common area exposure detection information with the camera B or C.
By performing the correction processing as described above, it is possible to suppress a brightness imbalance that occurs at the boundary between the camera image areas and provide a natural image.

FIG. 6 is a flowchart of the exposure correction process in FIG.
In step S601, exposure detection information Iab (A), Iab (B),... Of each camera image in each common imaging area Sab, Sac, Sbd, Scd is acquired. In step S602, the magnitude relationship of each common area exposure detection information is examined to determine which case shown in FIG. When the case is determined, the necessity of exposure correction is determined by a predetermined rule. For example, in cases 1 to 6 in FIG. 5, correction = necessary, and otherwise, correction = unnecessary. If exposure correction = necessary, in step S603, a camera to be subjected to exposure correction is determined. For example, in case 1 of FIG. 5, camera A and camera D are correction targets, and in case 3, camera B and camera C are correction targets.

  In step S604, an exposure deviation amount is calculated for one correction target camera. For example, for the camera A, ΔI (A) is calculated by the above equation (1) by taking the average of the difference between the camera B and the difference between the camera C and the common area exposure detection information. In step S605, an exposure correction amount is calculated for the correction target camera. For example, for camera A, ΔE (A) is calculated by the equation (2). In step S606, the exposure balance point is corrected in the direction of increasing (or decreasing) the brightness by the exposure correction amount with respect to the correction target camera.

  In step S607, it is determined whether other correction target cameras remain. For example, in case 1, since the camera D remains, the process returns to step S604 and exposure correction is performed in the same manner.

  According to the embodiment of FIGS. 5 and 6, a case in which imbalance is likely to occur and a correction method for the case are registered in advance, and exposure correction is executed in accordance with this, so that the correction processing time can be shortened.

  By the exposure control balance point correction according to the first embodiment, it is possible to eliminate the brightness imbalance at each camera imaging area boundary. However, a display image with brightness suitable for practical use is not always obtained. For example, an image obtained by photographing the sunlit portion (image of camera A in case 1) transitions to an overexposed (too bright) image, or an image obtained by photographing only the shaded portion (image of camera D in case 1). ) Transitions to a black sunken (too dark) image, and in particular, recognition of an image in a dark part may be insufficient. Therefore, in the second embodiment, non-linear control of luminance gradation is performed in addition to balance point correction control of exposure control.

  FIG. 7 is a diagram for explaining non-linear control of luminance gradation. As the non-linear control, tone control called “gamma processing” indicated by the correction curve 71 and tone control generally called “contrast” shown by the correction curve 72 are effective. In any correction, when the gradation of the input luminance signal is large, a luminance signal with a lowered gradation is output, and when the gradation of the input luminance signal is small, a luminance signal with an increased gradation is output.

  FIG. 8 is a diagram illustrating an example of luminance correction to which non-linear control of luminance gradation is added. (A) is an original luminance distribution in the case 1, and (b) is a state in which exposure corrections A ′ and D ′ are applied to the cameras A and D according to the first embodiment. By the exposure correction, the luminance level of the image of the camera A is corrected and the luminance level of the camera D is corrected low. (C) is a diagram for explaining correction of luminance gradation by the correction curves 71 and 72 of FIG. Since the image of the camera A and the sunny partial image of the camera B have high luminance gradation, the gradation is lowered by the correction A ″ and the correction B1 ″. On the other hand, the image of the camera D and the shaded partial image of the camera B have a low luminance gradation, so that the gradation is increased by the correction D ″ and the correction B2 ″.

  This luminance gradation control instruction is added to exposure correction information for the corresponding camera and transmitted, and a luminance gradation correction command 18 is sent to the video processing circuit 13 to perform gradation correction on the corresponding image signal. Alternatively, a luminance gradation control instruction is transmitted to the display processing circuit 34 of the central controller 30, and the display processing circuit 34 performs gradation correction on the corresponding image signal. When gradation correction is performed by the video processing circuit 13 of the camera, since the entire area of the image of the camera A has the same luminance, the correction A ″ for gradation control for the camera A is applied to the camera A. It is also possible to include the exposure correction A ′ and control it with a single command, and the same result can be obtained for the brightness of the output image, and the same applies to the camera D whose entire area has the same luminance.

  According to the present embodiment, brightness gradation non-linearization control is performed in addition to exposure control balance point correction to display an image with more natural brightness and excellent dark area recognition. Can do.

  In each of the above-described embodiments, a case has been described in which the luminance imbalance of images taken by each camera is eliminated. In addition to this, when generating a composite image, unbalance may occur in the color temperature control performed by each camera. In that case, it is needless to say that the color imbalance regarding color reproduction can be alleviated by comparing the color information of the common imaging area and reflecting it in the color tone control of each camera by the procedure shown in the embodiment.

1 is a system configuration diagram showing an embodiment of an imaging system of the present invention. FIG. 3 is a diagram illustrating a common imaging area provided in each camera in the present embodiment. The figure explaining the imbalance of the brightness which generate | occur | produces in a synthesized image, and its correction principle. The figure which shows the general flowchart of the exposure correction process of a present Example. The figure which shows the typical example of exposure correction of a synthesized image. The figure which shows the flowchart of the exposure correction process of FIG. The figure explaining the non-linear control of the brightness | luminance gradation by a present Example. The figure which shows the example of the brightness correction which added the non-linear control of the brightness | luminance gradation.

Explanation of symbols

10 ... Camera,
11 ... Optical system,
12: Image sensor,
13 ... Video processing circuit,
14: Exposure detection information,
15 ... transmission processing circuit,
16: Exposure correction information,
17 ... processor,
18 ... luminance gradation correction command,
19 ... exposure control command,
20 ... transmission line,
21 ... Image signal,
22 ... Common area exposure detection information,
23: Exposure correction information,
30 ... Central control unit,
31 ... Transmission processing circuit,
32 ... Memory,
33 ... Processor,
34 ... display processing circuit,
40. Image display unit,
Sab, Sac, Sbd, Scd... Common imaging area.

Claims (5)

In an imaging system that transmits images taken by a plurality of cameras to a central control unit and synthesizes and displays images from each camera,
Each of the cameras has a common imaging area, which is an area shared with other cameras, in the imaging area to be photographed, and processes the photographed image signal and detects the luminance signal of the common imaging area portion in common. A video processing circuit that generates area exposure detection information, a captured image signal, a transmission processing circuit that transmits the common area exposure detection information to the central control device, and outputs an exposure control signal to the optical system and the image sensor With a camera processor,
The central control unit compares the display processing unit that synthesizes the image signals transmitted from the respective cameras and displays them on the image display unit, and the common area exposure detection information transmitted from the respective cameras. An imaging system comprising a central processor for outputting exposure correction information to a corresponding camera in accordance with a difference between cameras in common area exposure detection information in an imaging area. The imaging system according to claim 1,
When the difference between the common area exposure detection information of the two cameras in the same common imaging area is larger than a predetermined threshold, the central processor of the central control unit performs necessary exposure correction based on the difference between the common area exposure detection information An imaging system that calculates an amount and outputs exposure correction information to one camera. The imaging system according to claim 2,
The central processor of the central control unit sets a correction reference camera as a reference for exposure correction from among the plurality of cameras, and compares it with other cameras while comparing with the common area exposure detection information of the correction reference camera. An imaging system characterized by sequentially outputting exposure correction information. The imaging system according to claim 2,
The central processor of the central control unit previously classifies the magnitude relationship of the common area exposure detection information of the two cameras in each common imaging area, and what exposure correction is performed for which camera in each case. An imaging system, wherein whether to output information is determined in advance. The imaging system according to any one of claims 1 to 4,
The video processing circuit of each camera has a function of performing non-linear luminance gradation correction on a captured image signal,
The imaging system according to claim 1, wherein the central processor of the central control device controls a luminance gradation correction operation for a video processing circuit of a corresponding camera according to the luminance gradation of the transmitted image signal.

Images