JP2009257780A - Imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image having sufficient brightness while suppressing noise. <P>SOLUTION: This imaging system is equipped with a light sending part 11 for emitting pulse-like light, a light receiving part 12, an image processing device 25 for accumulating image signals output from the receiving part 12 over a frame period, and outputting a superposed signal superposing a plurality of accumulated signals, a display 4 for displaying the superposed signal as an image, and a control device 3 for adjusting the brightness of the image displayed on the display 4, by adjusting the gain of a camera head 123 and the pulse frequency of the laser light emitted from the sending part 11 within their preset respective tolerances. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging system for imaging an obstacle or the like in a ship or the like.

2. Description of the Related Art Conventionally, a system using a laser radar is known as a system that is installed on a ship or the like and detects an object over a wide range (see, for example, Patent Document 1).
Such a system using a laser radar displays, for example, a laser radar 51, a laser radar control unit 52 for controlling the laser radar 51, and an image signal obtained by the laser radar 51, as shown in FIG. And a display unit 53. The laser radar 51 is configured such that its elevation angle and rotation angle are controlled by a turntable 54.
In such a configuration, at the time of imaging, a pulse laser beam is emitted from the laser head in the laser radar 51 to the periphery of the ship, and this laser beam reaches the object A and reflects the reflected light in the laser radar. An image is captured by the camera provided in, and an image signal is output to the display unit 53, whereby an object existing around is displayed on the display unit 53.
JP 2006-317303 A

  In the conventional laser radar as described above, the brightness of the image displayed on the display unit 53 is adjusted by adjusting the gain of the camera. However, when the camera gain is increased, there is an inconvenience that an electrical image noise generated in a circuit portion in the camera increases and the image becomes rough.

  The present invention has been made to solve the above problems, and an object thereof is to provide an imaging system capable of obtaining an image with appropriate brightness while suppressing noise.

In order to solve the above problems, the present invention employs the following means.
The present invention is a light transmitting means for emitting pulsed light, and the shutter is opened in accordance with the timing when the pulsed light emitted from the light transmitting means reaches the object and the reflected light reflected by the object arrives. An imaging unit that converts the captured reflected light into an image signal and outputs the image signal, and accumulates the image signal output from the imaging unit over a predetermined period, and superimposes a superimposed signal obtained by superimposing a plurality of accumulated image signals. Image processing means for outputting, display means for displaying the superimposed signal output from the image processing means as an image, gain of the imaging means and pulsed light emitted from the light transmitting means are preset. By providing an adjustment within the allowable range, a control unit that adjusts the brightness of the image displayed on the display unit is provided.

  According to such a configuration, it is possible to adjust the brightness of the image not only by relying on the gain of the image pickup means but also by changing the pulsed light emitted from the light sending means. This makes it possible to adjust the brightness of the image while suppressing noise.

  In the imaging system, the control unit may adjust the brightness of the image by increasing or decreasing the emission frequency of the pulsed light emitted from the light transmission unit.

  By increasing or decreasing the emission frequency of the pulsed light, the amount of light incident on the imaging means can be increased or decreased, and the brightness of the image can be adjusted.

  In the imaging system, the control unit may adjust the brightness of the image by increasing or decreasing the amplitude of the pulsed light emitted from the light transmitting unit.

  By increasing or decreasing the amplitude of the pulsed light emitted from the light transmitting means, the amount of light incident on the imaging means can be increased or decreased, and the brightness of the image can be adjusted.

  In the imaging system, the control unit may adjust the brightness of the image by increasing or decreasing the pulse width of the pulsed light emitted from the light transmitting unit.

  By increasing or decreasing the pulse width of the pulsed light emitted from the light transmitting means, the amount of light incident on the imaging means can be increased or decreased, and the brightness of the image can be adjusted.

  In the imaging system, the control unit provides a period in which the shutter of the imaging unit is continuously closed within the predetermined period, and increases or decreases the period in which the shutter is continuously closed. The brightness may be adjusted.

  As described above, the period in which the shutter is continuously closed is provided, and the period in which the shutter is continuously closed is increased / decreased, so that the amount of reflected light taken in by the imaging unit can be adjusted. As a result, the number of image signals used when creating the superimposed signal can be increased or decreased, and the brightness of the image can be adjusted.

  In the imaging system, the control unit adjusts the gain of the imaging unit within a predetermined range, and the pulsed light emitted from the light transmission unit when the brightness of the image cannot be adjusted with the gain alone. It is good also as adjusting.

  If the image does not reach the desired brightness even when the gain of the imaging means is increased in a range where noise is not an issue, the brightness of the image is adjusted by changing the pulsed light. Thereby, noise can be effectively suppressed.

  In the imaging system, when the desired brightness cannot be ensured even if the gain and the pulsed light are increased within the allowable range, the control unit exceeds the allowable range with the gain of the imaging unit. It may be increased.

  If the brightness of the desired image cannot be ensured even if the pulse is changed, the gain of the imaging means is increased while allowing the noise to increase. Thereby, although noise increases, an image having a desired brightness can be acquired.

  The present invention provides illumination means for irradiating light, imaging means for converting reflected light reflected by an object into an image signal, and outputting the image signal output from the imaging means for a predetermined period. An image processing unit that accumulates and outputs a superimposed signal obtained by superimposing a plurality of accumulated image signals, a display unit that displays the superimposed signal output from the image processing unit as an image, and a gain of the imaging unit There is provided an imaging system including a control unit that adjusts the brightness of the image displayed on the display unit by adjusting within a preset allowable range.

  According to the present invention, it is possible to obtain an image with appropriate brightness while suppressing noise.

Embodiments of an imaging system according to the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a block diagram showing the overall configuration of an imaging system according to the first embodiment of the present invention. As shown in FIG. 1, the imaging system according to this embodiment includes a laser radar 1, a laser radar control unit 2, a control device (control means) 3, a display device (display means) 4, a turntable 5, and an input device 6. It is configured with.

The laser radar 1 includes a light transmitting unit (light transmitting unit) 11 and a light receiving unit (imaging unit) 12.
For example, the light transmission unit 11 adjusts the angles of a laser oscillator 111 that emits pulsed laser light, a light transmission lens 112 that irradiates a target with the laser light emitted from the laser oscillator 111, and the light transmission lens 112. A light transmission lens actuator (not shown) is provided as a main component.

  The laser oscillator 111 is supplied with power from a laser power source 26 in the laser radar control unit 2 to be described later, and emits pulsed laser light (hereinafter referred to as “pulse light”). The light transmission lens actuator adjusts the position of the light transmission lens 112 based on a control signal supplied from a laser radar control unit 2 described later. Thereby, the angle of the laser light incident on the light transmission lens 112 can be adjusted, and the pulsed light can be emitted in a desired range.

  The light receiving unit 12 includes, for example, a zoom lens 121, a shutter device 122, and a camera head 123. The zoom lens 121 condenses the reflected light emitted from the light transmitting unit 11 and reflected by the target and guides it to the shutter device 122.

The shutter device 122 is driven by a shutter device control unit 24 provided in the laser radar control unit 2 to be described later, and functions as a shutter that takes the light guided by the zoom lens 121 into the camera head 123. The camera head 123 converts the captured light into an electrical signal to generate an image signal, and outputs this image signal to the image processing device (image processing means) 25 in the laser radar control unit 2.
Such a laser radar 1 has a structure in which the rotation angle and the attack angle are adjusted to desired angles by the swivel base 5.

  The laser radar control unit 2 includes a light transmitting unit 11 of the laser radar 1, a light receiving unit 12, and a turntable 5 that adjusts the rotation angle of the laser radar 1 based on various control signals supplied from the control device 3. Control. The laser radar control unit 2 includes, for example, a turntable drive unit 21, a synchronization circuit 22, a control signal conversion device 23, a shutter device control unit 24, an image processing device 25, a laser power source 26, and the like.

The control device 3 generates various control signals for controlling the laser radar 1, outputs the generated various control signals to the laser radar control unit 2, and superimpose signals (details are supplied from the laser radar control unit 2). (Described later) is output to the display device 4.
The display device 4 displays the superimposed signal input from the control device 3. The input device 6 performs an input operation by the user and outputs an input signal based on the operation information to the control device 3.

The laser radar control unit 2 and the control device 3 described above are, for example, a CPU (Central Processing Unit), an HDD (Hard).
A computer system including a disk drive (ROM), a read only memory (ROM), a random access memory (RAM), and the like is incorporated. A series of processing steps for realizing various functions to be described later are recorded in a HDD or the like in the form of a program, and the CPU reads the program into a RAM or the like and executes information processing / arithmetic processing. Various functions to be described later are realized.

  Note that the arrangement of the devices constituting the imaging system is not limited to the arrangement illustrated in FIG. For example, in the present embodiment, it is assumed that the laser oscillator 111 is arranged in the laser radar 2, but instead, for example, the laser oscillator 111 is arranged separately in the laser radar control unit or outside the laser radar 2. It is good. As described above, the arrangement of the components of the imaging system can be appropriately changed within a range where the present invention can be applied.

Next, the operation of the imaging system according to the present embodiment will be described.
First, at the time of imaging, the control device 3 uses the synchronization control signal necessary for emitting the laser light at a predetermined timing, and the reflected light reflected when the laser light emitted at the predetermined timing reaches a predetermined object. Only a shutter drive signal or the like to be taken into the camera head 123 included in the light receiving unit 12 is generated and output to the laser radar control unit 2.

The synchronization control signal and the shutter drive signal output from the control device 3 are supplied to the synchronization circuit 22 and the shutter device control unit 24 via the control signal conversion device 23 in the laser radar control unit 2, respectively.
The synchronization circuit 22 generates a synchronization signal for synchronizing the transmission and reception of the laser beam based on the input synchronization control signal, and outputs this synchronization signal to the laser power source 26 and the shutter device controller 24. .

  The laser power source 26 generates an operation signal of the laser oscillator 111 in the light transmitting unit 11 included in the laser radar 1 based on the synchronization signal supplied from the synchronization circuit 22, and drives the laser oscillator 111 based on the operation signal. To do. As a result, pulsed laser light is emitted from the laser transmitter 111 at a predetermined timing.

  On the other hand, the shutter device control unit 24 drives the shutter device 122 of the light receiving unit 12 included in the laser radar 1 based on the shutter drive signal input from the control device 3 and the synchronization signal input from the synchronization circuit 22.

  As a result, first, the laser oscillator 111 is driven by the laser power source 26, whereby pulse laser light is emitted from the laser oscillator 111 at a predetermined timing. The pulsed laser light is expanded to an irradiation area having a predetermined range by the light transmission lens 112, is emitted to the outside, and the laser light reflected by an object existing in the irradiation area is guided to the light receiving unit 121. Will be. In this case, the above-described shutter device control unit 24 drives the shutter device 122 based on the shutter drive signal, so that only the laser light reflected by the object can be taken into the camera head 123 (FIG. 2).

  Then, the light information captured by the camera head 123 is converted into an image signal that is an electrical signal and output to the image processing device 25 in the laser radar control unit 2. The image processing device 25 accumulates the image signal output from the camera head 123 in a predetermined period set in advance, for example, in a period of one frame as shown in FIG. Then, a superimposed signal having a high voltage value is generated by superimposing the accumulated image signal, and this superimposed signal is output. The greater the number of image signals to be superimposed, the higher the luminance of the superimposed signal.

  The superimposed signal from the image processing device 25 is input to the control device 3 via the control signal conversion device 23. The control device 3 outputs the input superimposed signal as an image to the display device 4. Thereby, the outline of the suspended | floating matter P etc. will be displayed on the display monitor of the display apparatus 4 clearly (high brightness | luminance) as visible information. As a result, when the user (crew or the like) confirms the image displayed on the display monitor, it is possible to acquire information such as the shape and size of the object present in the irradiation region.

  Next, image brightness adjustment, which is a feature of the present invention, will be described with reference to FIG.

  When an image is displayed on the display device 4 by the operation as described above, the user determines whether or not the brightness of the image is sufficient. By operating, an instruction to increase brightness is input.

  When the control device 3 receives the instruction to increase the brightness, the control device 3 executes a brightness adjustment process shown in FIG. First, the control device 3 determines whether or not the current gain of the camera head 123 is greater than or equal to a preset upper limit value (step SA1 in FIG. 4). Here, the upper limit value is set to an upper limit value in a range where noise does not occur. The determination as to whether or not noise has occurred is made, for example, by calculating the standard deviation of the voltage of the image signal.

  In step SA1, if the gain is less than the upper limit value, the control device 3 generates a control signal for increasing the gain by a predetermined amount and outputs the control signal to the laser radar control unit 2. The laser radar control unit 2 adjusts the camera head 123 to increase the gain of the camera head 123 by a predetermined amount (step SA2 in FIG. 4).

As a result, the brightness of the image signal output from the light receiving unit 12 increases, and as a result, the image with the increased brightness is displayed on the display device 4 (step SA3 in FIG. 4). The user determines whether or not the brightness of the image is sufficient. If the image is not sufficient, the user inputs a brightness increase adjustment instruction from the input device 6, and if it is sufficient, inputs an end instruction (step SA4 in FIG. 4). ).
If an instruction to end is input, this process ends. On the other hand, if an instruction to increase brightness adjustment is input again, the process returns to step SA1, and the processes after step SA1 are repeated.

  At this time, if the current gain of the camera head 123 is greater than or equal to the upper limit value in step SA1, the control device 3 stops the gain increase adjustment and adjusts the pulse frequency of the transmission unit 11 to Adjust the brightness.

  Specifically, the control device 3 first determines whether or not the pulse frequency of the pulsed laser light emitted from the light transmitting unit 11 is equal to or higher than a preset upper limit value (step SA5 in FIG. 4). . Here, the upper limit value of the pulse frequency is set to, for example, a value when the brightness of the image does not change even when the pulse frequency is increased, or a limit value of the capability. In this embodiment, as an example, the value is set to a value at which the energy per pulse starts to decrease.

  In step SA5, when the pulse frequency is less than the upper limit value, the control device 3 generates a control signal for increasing the pulse frequency by a predetermined amount and outputs the control signal to the laser radar control unit 2. The laser radar controller 2 increases the frequency of the pulse laser beam emitted from the laser transmitter 111 by increasing the frequency of the operation signal of the laser transmitter 111 of the light transmitter 11 by a predetermined amount (step of FIG. 4). SA6).

  At this time, the driving frequency of the shutter device 122 is also adjusted according to the driving frequency of the pulse laser beam. Accordingly, the shutter device 122 opens and closes in synchronization with the timing at which the laser beam is emitted from the laser transmitter 111, and only the laser beam reflected by the object can be taken into the camera head 123.

  As a result, the number of image signals output from the light receiving unit 12 within the frame period increases. Thereby, the brightness of the superimposed signal created by the image processing device 25 increases, and this superimposed signal is displayed as an image on the display device (step SA7 in FIG. 4).

  The user determines whether or not the brightness of the image is sufficient. If the image is not sufficient, the user inputs an instruction to increase the brightness from the input device 6, and if it is sufficient, inputs an instruction to end (step in FIG. 4). SA8). If an instruction to end is input, this process ends. On the other hand, if an instruction to increase brightness adjustment is input again, the process returns to step SA5, and the processes after step SA5 are repeated.

  At this time, if the current pulse frequency of the laser beam is greater than or equal to the upper limit value in step SA5, the control device 3 stops increasing adjustment of the pulse frequency, and this time increases the gain of the camera head 123 again. By doing so, the brightness of the image is increased (step SA9 in FIG. 4). Then, until an end signal indicating that the brightness of the image is sufficient is input, the control device 3 performs a process of increasing the gain by a predetermined amount (steps SA10 and SA11 in FIG. 4).

  By performing such control by the control device 3, as shown in FIG. 5, first, the brightness of the image is increased by increasing the gain of the camera head 123, and the brightness is insufficient only by the gain. In this case, the brightness of the image is increased by increasing the pulse frequency of the pulse laser beam. If sufficient image brightness cannot be obtained with only the pulse frequency of the pulsed laser light, noise generation is allowed and the gain of the camera head 123 is increased.

  As described above, according to the imaging system according to the present embodiment, by changing the pulse frequency of the pulsed laser light emitted from the light transmitting unit 11 instead of depending only on the gain of the camera head 123. Since the brightness of the image is adjusted, it is possible to adjust the brightness of the image while suppressing noise.

  In the above embodiment, the case where the brightness of the image displayed on the display device 4 is increased has been described as an example. Similarly, the brightness of the image is reduced by decreasing the gain and the pulse frequency. It is also possible to make it. In this way, the screen can be adjusted to a desired brightness by adjusting the gain and the pulse frequency.

  In the above embodiment, the pulse frequency of the pulse laser beam is increased after the gain of the camera head 123 is increased. Instead, the pulse frequency of the pulse laser beam is increased first. When the brightness is insufficient, the gain of the camera head 123 may be increased.

[Second Embodiment]
Next, an imaging system according to the second embodiment of the present invention will be described.
In the first embodiment described above, the brightness of the image is increased by increasing the pulse frequency of the pulse laser beam. However, in the present embodiment, as shown in FIG. The brightness of the image is increased by increasing the amplitude. The upper limit value of the amplitude of the pulse at this time is set to a maximum value determined by, for example, a peak intensity limit value or a light resistance intensity limit of components such as lenses and windows.

  As a method of adjusting the amplitude of the pulse, for example, a method of adjusting the excitation current of the laser oscillator 111 or a method of adjusting using an optical filter or the like can be employed.

  According to the imaging system according to the present embodiment, since the light intensity of each pulse is increased or decreased, the amount of reflected light incident on the light receiving unit 12 can be increased or decreased. Thereby, the brightness of the image can be adjusted to an appropriate brightness.

[Third Embodiment]
Next, an imaging system according to a third embodiment of the present invention will be described.
In the first embodiment described above, the luminance of the image is increased by increasing the pulse frequency of the laser beam. However, in this embodiment, the pulse width of the laser beam is increased as shown in FIG. By doing so, the luminance of the image is increased.

  If the pulse width is excessively widened, the shutter opening time becomes long, and surrounding noise light components are also taken in. Therefore, an appropriate pulse width is set in advance in consideration of a trade-off with the noise light component to be captured. Specifically, the image signal is monitored in advance, and an appropriate upper limit value is set based on indicators such as signal level and standard deviation. Here, since the noise light component changes depending on weather conditions such as fine weather and rainy weather, an upper limit value may be set according to the weather.

  According to the imaging system according to the present embodiment, the amount of light taken into the camera head 123 can be increased or decreased by increasing or decreasing the pulse width of the laser light. As a result, the image can be adjusted to an appropriate brightness.

[Fourth Embodiment]
Next, an imaging system according to a fourth embodiment of the present invention will be described.
In the first embodiment described above, the luminance of the image is increased by increasing the pulse frequency of the laser light. However, in this embodiment, as shown in FIG. 8, the shutter device 122 in one frame period. The brightness of the image is increased by increasing and decreasing the number of reflected light pulses captured by the ICCD camera header 123 in one frame period by increasing and decreasing the period for the closed state. To adjust.
In this embodiment, the frequency, amplitude, and pulse width of the pulse emitted from the laser oscillator 111 are constant, and the pulse transmitter 111 is always driven under the same conditions.

  According to the imaging system according to the present embodiment, the number of image signals constituting the superimposed signal can be increased or decreased, and as a result, the brightness of the image can be increased or decreased. In addition, unlike the first to third embodiments described above, it is not necessary to change the pulse frequency, amplitude, and pulse width of the laser light, and it can be driven under certain conditions, so that the light source and its driving system are burdened. The brightness of the image can be adjusted without applying. Thereby, the lifetime of the light transmission part 11 and the laser radar control part 2 can be extended, and the stable operation | movement is attained.

  The adjustment of the pulse laser light according to the first to third embodiments can be arbitrarily combined. For example, the control may be performed so that all or part of the pulse frequency, pulse amplitude, and pulse width are increased or decreased by a predetermined amount.

  In addition, the method of adjusting the pulse width is susceptible to noise from ambient light when the weather conditions are bad. In this case, the brightness is adjusted by changing the pulse frequency and pulse amplitude. Also good. Thus, by selecting an effective adjustment method according to the situation, it is possible to efficiently adjust the brightness of the image.

  In the above embodiment, the user determines whether or not sufficient luminance has been obtained. However, this determination may be performed automatically. In this case, the brightness of the image may be calculated using a statistical method, and it may be determined whether the brightness is sufficient depending on whether the brightness is equal to or higher than a preset threshold value. By automatically determining the brightness in this way, the burden on the user can be greatly reduced, and the brightness of the image is automatically determined so that the brightness of the image is determined quantitatively and a constant brightness is always ensured. Adjustments can be made.

  Moreover, in each embodiment mentioned above, although it was set as the light transmission part 11 provided with the laser oscillator 111 as a light source, the structure of the light transmission part 11 is not limited to this example. For example, instead of the laser oscillator 111, a lamp that emits light continuously may be employed. As described above, it is also possible to employ a light projection type camera or the like as the light transmitter 11 and the light receiver 12. In this case, the brightness of the image can be adjusted by adjusting the intensity of the light emitted from the lamp and the camera gain.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

1 is a block diagram illustrating a schematic configuration of an imaging system according to a first embodiment of the present invention. It is a figure for demonstrating operation | movement of a laser radar. It is a figure for demonstrating operation | movement of a laser radar. It is the figure which showed the flowchart of the brightness adjustment process of the image which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the brightness adjustment method of the image in the imaging system which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the brightness adjustment method of the image in the imaging system which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the brightness adjustment method of the image in the imaging system which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the brightness adjustment method of the image in the imaging system which concerns on the 4th Embodiment of this invention. It is the figure shown about the conventional system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser radar 2 Laser radar control part 3 Control apparatus 4 Display apparatus 5 Turntable 6 Input device 11 Light transmission part 12 Light receiving part 21 Turntable drive part 22 Synchronous circuit 23 Control signal converter 24 Shutter apparatus control part 25 Image processing apparatus 26 Laser power supply 111 Laser oscillator 112 Light transmission lens 121 Zoom lens 122 Shutter device 123 Camera head

Claims (8)

Light transmitting means for emitting pulsed light;
The shutter is opened at the timing when the pulsed light emitted from the light transmitting means reaches the object and the reflected light reflected by the object arrives, and the captured reflected light is converted into an image signal and output. Imaging means;
Image processing means for accumulating the image signal output from the imaging means over a predetermined period and outputting a superimposed signal obtained by superimposing a plurality of accumulated image signals;
Display means for displaying the superimposed signal output from the image processing means as an image;
Control means for adjusting the brightness of the image displayed on the display means by adjusting the gain of the imaging means and the pulsed light emitted from the light transmitting means within respective preset allowable ranges. An imaging system comprising:   The imaging system according to claim 1, wherein the control unit adjusts the brightness of the image by increasing or decreasing an emission frequency of pulsed light emitted from the light transmission unit.   The imaging system according to claim 1, wherein the control unit adjusts the brightness of the image by increasing or decreasing the amplitude of the pulsed light emitted from the light transmitting unit.   The imaging system according to claim 1, wherein the control unit adjusts the brightness of the image by increasing or decreasing a pulse width of the pulsed light emitted from the light transmitting unit.   The control means adjusts the brightness of the image by providing a period during which the shutter of the imaging means is continuously closed within the predetermined period, and increasing or decreasing the period during which the shutter is continuously closed. The imaging system according to any one of claims 1 to 4.   The control unit adjusts the gain of the imaging unit within a predetermined range, and adjusts the pulsed light emitted from the light transmission unit when the brightness of the image cannot be adjusted with the gain alone. The imaging system according to any one of claims 1 to 5.   The control unit increases the gain of the imaging unit beyond the allowable range when a desired brightness cannot be ensured even if the gain and the pulsed light are increased within the allowable range. The imaging system according to claim 6. Illumination means for irradiating light;
Imaging means for converting the reflected light reflected by the object into an image signal and outputting the image signal;
Image processing means for accumulating the image signal output from the imaging means over a predetermined period and outputting a superimposed signal obtained by superimposing a plurality of accumulated image signals;
Display means for displaying the superimposed signal output from the image processing means as an image;
An imaging system comprising: a control unit that adjusts the brightness of the image displayed on the display unit by adjusting a gain of the imaging unit within a preset allowable range.

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