JP4618062B2 - Monitoring device, monitoring system, and monitoring method - Google Patents

Description

  The present invention relates to a monitoring device, a monitoring system, and a monitoring method, and more particularly, to a monitoring device, a monitoring system, and a monitoring method that monitor a vehicle by photographing a monitoring region through which the vehicle passes.

  2. Description of the Related Art Conventionally, there has been a technique for compressing and storing a photographed image in order to monitor a vehicle passing through a road.

For example, Patent Literature 1 discloses a technique for compressing and storing an image of a road and storing identified license plate information. Patent Document 2 discloses a technique for compressing an image obtained by photographing a road and identified license plate information and transmitting the compressed information to a management center device. Patent Document 3 includes a license plate attached to the front side read from an image obtained by photographing the vehicle from the front and a license plate attached to the rear side read from an image obtained from the rear of the vehicle. Based on this, a technology for determining whether the vehicle is a normal vehicle or an unauthorized vehicle and analyzing information on the vehicle determined to be an unauthorized vehicle and storing information on the unauthorized vehicle is disclosed.
JP-A-9-261620 JP 2000-99698 A JP 2004-206441 A

  As described above, various techniques have been disclosed for monitoring a vehicle passing through a road. However, regarding a captured image of a vehicle, in order to store a specific vehicle as a fine image while further reducing the data amount of the image. The technology is always eagerly awaited.

  The present invention has been conceived in view of such circumstances, and an object of the present invention is to provide a monitoring device, a monitoring system, and a monitoring method for reducing the data amount of a captured image of a vehicle and storing a fine image for a specific vehicle. Is to provide.

The monitoring apparatus according to the present invention determines whether or not the license plate of the vehicle passing through the monitoring area is a specific license plate that satisfies a specific condition, based on a captured image obtained by capturing the monitoring area through which the vehicle passes. And a light-emitting unit that emits light toward the monitoring area, and the light-emitting unit emits light when the predetermined period is being increased by increasing the amount of light compared to when the predetermined period is not being performed. It is characterized by.
Further, the monitoring apparatus according to the present invention includes an image compression means to compress the captured image, the image compression means, the captured image being between before Kisho periodically, photographed image when not in the predetermined time period It is preferable to compress at a lower compression rate .

  Further, the monitoring apparatus according to the present invention further includes a photographing frequency control unit that controls a photographing frequency for photographing the photographed image, and the photographing frequency control unit includes the photographing frequency control unit during the predetermined period. It is preferable to increase the imaging frequency as compared to when not.

  The monitoring apparatus according to the present invention further includes a photographing magnification control unit that controls a photographing magnification for photographing the photographed image, and the photographing magnification control unit is configured to perform the predetermined period during the predetermined period. It is preferable to magnify the area including the windshield than when not.

  In the monitoring device according to the present invention, a feature point extracting unit that extracts a feature point of a vehicle based on the photographed image, and the feature point extracted by the feature point extracting unit passes a predetermined time in the photographed image. A moving distance calculating means for calculating a distance moved in between, wherein the photographing magnification control means includes an area including the windshield based on the feature point and the distance calculated by the moving distance calculating means. It is preferable to magnify and shoot.

  The monitoring apparatus according to the present invention further includes an infrared detecting unit that detects infrared rays having a predetermined wavelength from the monitoring region, and the imaging magnification control unit is configured to detect an infrared intensity change detected by the infrared detecting unit. Based on the above, it is preferable to magnify and shoot a region including the windshield.

  The monitoring apparatus according to the present invention further includes resolution setting means for setting the resolution of the captured image, and the resolution setting means is higher when the predetermined period is not during the predetermined period. It is preferable to set the resolution.

A monitoring system according to the present invention is a monitoring system including a monitoring device that monitors a monitoring region through which a vehicle passes, and a management device that manages an image from the monitoring device, the management device including a vehicle number. License plate information input means for inputting information relating to the plate, and license plate information transmission means for transmitting the information input by the license plate information input means to the monitoring device, wherein the monitoring device transmits the license plate information. includes an information storage means for storing information sent from the unit, a light emitting means for emitting light toward the monitoring area, and transmission means for transmitting the photographing field images taken the monitoring area to the management device, wherein management apparatus further comprises a management device side image storage means for storing a captured image transmitted by the transmission means, the monitoring Location is on the basis of the photographic image, further comprising a discriminating means for the license plate of a vehicle passing through the monitored area, it is determined whether or not a particular number plate that meet certain conditions, the light emitting means, the When it is during a predetermined period after the determination means determines that it is the specific license plate, it emits light with an increased amount of light compared to when it is not during the predetermined period .

The monitoring method according to the present invention determines whether or not a license plate of a vehicle passing through the monitoring area is a specific license plate that satisfies a specific condition, based on a captured image obtained by capturing the monitoring area through which the vehicle passes. comprising a determining step of discriminating that, a control step of controlling the light emitting means for emitting light toward the monitoring area, wherein the control step, the discrimination step is in a predetermined period after determining that the a particular number plate In some cases, the method includes a step of controlling the light emitting means so as to emit light with an increased amount of light as compared with when not in the predetermined period .

  When trying to store fine captured images for all vehicles, it is necessary to compress and store the captured images of all the vehicles at a low compression rate, which requires an enormous storage capacity. In addition, when transmitting an image, the amount of data becomes enormous, so traffic increases and a great deal of time is spent depending on the transmission speed. On the other hand, if the captured images of all the vehicles are compressed and stored at a high compression rate in order to reduce the amount of data, the images become coarse, so that a fine captured image of a specific vehicle to be monitored cannot be obtained.

According to the monitoring device according to the present invention, when the vehicle license plate is determined to be the specific license plate, the amount of light is increased when the vehicle is in the predetermined period than when the vehicle is not in the predetermined period. Thereby, a clear photographed image can be obtained for the vehicle having the specific number plate.
In addition, according to the monitoring device according to the present invention, the captured image of the vehicle with the specific number plate is compressed according to a lower compression ratio than the captured image of the vehicle that is not the specific license plate. Thereby, it is possible to obtain a fine image of the vehicle of the specific number plate while reducing the amount of image data.

  In addition, according to the monitoring device according to the present invention, the imaging frequency is increased when it is during the predetermined period than when it is not during the predetermined period. Thereby, more photographed images can be obtained for the vehicle having the specific number plate.

  Further, according to the monitoring device according to the present invention, the area including the windshield is photographed in an enlarged manner during the predetermined period than when it is not during the predetermined period. Thereby, since a windshield can be expanded and image | photographed, the image which image | photographed the passenger of the vehicle of the specific number plate can be obtained.

  In addition, according to the monitoring device according to the present invention, the region including the windshield is enlarged and photographed based on the feature point of the vehicle and the distance the vehicle has moved during a predetermined time. As a result, an enlarged image obtained by enlarging the windshield at a pinpoint can be obtained.

  In addition, according to the monitoring device according to the present invention, an area including the windshield is enlarged and photographed based on the change in the intensity of infrared rays. As a result, an enlarged image obtained by enlarging the windshield at a pinpoint can be obtained.

  In addition, according to the monitoring device according to the present invention, a higher resolution is set when it is during the predetermined period than when it is not during the predetermined period. Thereby, a fine image can be obtained for the vehicle of the specific license plate.

According to the monitoring system according to the present invention, the license plate of the vehicle is input and transmitted to the monitoring device in the management device. In the monitoring device, it is determined whether or not the license plate of the vehicle is a specific license plate, and it is not in a predetermined period when it is determined that the license plate of the vehicle is a specific license plate. Increase the amount of light than sometimes. Further, the captured image is transmitted to the management device in the monitoring device. In the management device, the transmitted captured image is stored. This makes it possible to collectively manage the management apparatus clear images for vehicles of specific license plate.

According to the monitoring method according to the present invention, when the vehicle license plate is determined to be the specific license plate, the light quantity is increased when the vehicle is in the predetermined period than when the vehicle is not in the predetermined period. Thus, it is possible to obtain a clear image for the vehicle of a specific license plate.

  Hereinafter, a monitoring system 1 including a road processing device 5 which is a monitoring device according to an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference symbols, unless otherwise specified, and have the same names and functions. Therefore, detailed description thereof will not be repeated.

[First Embodiment]
The monitoring system 1 according to the first embodiment photographs a part of a road in order to monitor a vehicle passing through the road. FIG. 1 is a perspective view schematically illustrating a part of a road to be monitored by the monitoring system 1 according to the first embodiment. FIG. 1 shows a one-lane road network on one side.

  With reference to FIG. 1, the vehicle 9 travels straight on a road 10. At the side of the road, one end of an L-shaped column is embedded and installed. A monitoring device connected to the L-shaped support column is connected to the plate recognition camera 3 and the image capturing camera 4 for capturing the vehicle passing through the road, and the plate recognition camera 3 and the image capturing camera 4. A road processing device 5 is attached.

  The plate recognition camera 3 and the image capturing camera 4 are housed in one housing 2. The housing 2 in which the plate recognition camera 3 and the image capturing camera 4 are housed is attached at a position above the road. On the other hand, the road processing device 5 is attached to a position near the ground of the support column.

  The plate recognition camera 3 is a camera for photographing a license plate recognition area 6 (area surrounded by a dotted line in FIG. 1). The image capturing camera 4 is a camera for capturing the monitoring area 7 (the hatched area in FIG. 1). The plate recognition camera 3 and the image capturing camera 4 include a monitoring area 7 in the license plate recognition area 6, and the monitoring area 7 is closer to the traveling direction side of the vehicle than the license plate recognition area 6 (front side as viewed from the camera). ), The field of view and the depression angle are adjusted respectively.

  The plate recognition camera 3 in the first embodiment has a high resolution because it needs to recognize a license plate as will be described later, and uses a camera that photographs in the infrared region. The image capturing camera 4 uses a camera that captures images in the visible light region during the day and in the infrared region at night. As described above, the road processing device 5 according to the first embodiment uses two cameras having different performances suitable for applications, and thus is a multifunctional and expensive device that performs plate recognition and image shooting with a single device. Compared with a road processing apparatus using a camera, the cost of the road processing apparatus can be reduced. Thereby, it becomes easy to increase the number of installation of the roadside processing apparatus 5, and the number of points monitored by the roadside processing apparatus 5 increases, so that the monitoring level can be improved. However, the present invention is not limited to this, and the road processing apparatus may be one using a single camera.

  FIG. 2 is a control block diagram of the monitoring system 1. Referring to FIG. 2, monitoring system 1 includes a plurality of road processing devices 5 connected to plate recognition camera 3 and image capturing camera 4, and a central processing device capable of communicating with each of the plurality of road processing devices 5. 40. The roadside processing device 5 in the first embodiment is provided for each predetermined monitoring point. The images captured by the plate recognition camera 3 and the image capturing camera 4 are transmitted to the central processing unit 40 after being subjected to various processing described later in the road processing device 5. The central processing unit 40 is installed, for example, in a police station or the like that monitors and controls a vehicle.

  The road processing device 5 includes a processing unit 20 that performs various processes, which will be described later, and an image storage unit 21 that stores an image captured by the plate recognition camera 3 and the image capturing camera 4 and compressed. . The image storage unit 21 is configured by a storage medium such as a flash memory, for example.

  The processing unit 20 includes a camera control unit 50 that controls shooting by the plate recognition camera 3 and the image shooting camera 4, an image analysis unit 51 that analyzes the shot image, and a number based on an analysis result by the image analysis unit 51. A license plate recognition area intrusion determination unit 52 that determines whether or not a vehicle has entered the plate recognition area 6, a license plate information identification unit 53 that identifies information on the license plate of the vehicle, and a monitoring target A monitoring vehicle information storage unit 54 that stores information related to the monitoring vehicle (including information such as license plate characters and numbers, vehicle emblems, vehicle colors, etc.) and a monitoring vehicle information stored in the monitoring vehicle information storage unit 54 By comparing the information on the license plate with the information on the license plate of the intruding vehicle to match (completely match or partially match) A vehicle determination unit 55 that determines whether or not a specific condition to be satisfied is satisfied, a compression unit 56 that compresses an image captured at a predetermined compression rate, a determination result by the vehicle determination unit 55, and the plate recognition camera 3. A storage processing unit 57 that stores the photographed image and the image compressed by the compression unit 56 in the image storage unit 21 and a communication unit 58 for communicating various information with the central processing unit 40 are included.

  The central processing unit 40 includes a server 41 for communicating various information with the road processing unit 5 and a plurality of PCs (Personal Computers) 42 connected to the server 41 and operable by an operator. Note that the PC is described as an example of a configuration that can be operated by the operator. However, the present invention is not limited to this, and any configuration that can be operated by the operator, such as a workstation, may be used.

  The server 41 includes a communication unit 43 for communicating various types of information with the road processing device 5, a storage unit 44 that stores an image transmitted from the road processing device 5, and a predetermined number of images stored in the storage unit 44. A search unit 45 for searching for an image.

  Each of the PCs 42 is connected to a mouse, a keyboard, and a monitor. The operator operates the mouse and the keyboard, and includes information related to the monitored vehicle (number plate characters and numbers, vehicle emblems, vehicle colors, and the like). ), An input process for inputting information to be searched by the search unit 45 of the server 41, an image display process for displaying the image searched by the search unit 45 on the monitor, and the like.

  For example, when all the license plates, for example, “Kobe 11 a 4249” are set as monitoring vehicles, “Kobe 11 a 4249” is input as information related to the monitoring vehicle in the input process. In addition, when inputting a part of the license plate, for example, “249” in the serial number as a specific condition, “249” is input in the input process. In addition, in the input process, the emblem of the vehicle, the color of the vehicle, and the like are input as necessary. In this way, the input information (including information such as license plate characters and numbers, vehicle emblems, and vehicle colors) is transmitted to the plurality of road processing devices 5 by the communication unit 43. In the road processing device 5 that has received these pieces of information, processing to be stored in the monitored vehicle information storage unit 54 included in the processing unit 20 is performed.

  Next, photographing processing for performing photographing by the plate recognition camera 3 and the image photographing camera 4 and compression of the photographed image in the road processing device 5 of the first embodiment will be described. FIG. 3 is a flowchart for explaining the photographing process. The photographing process is repeatedly executed every predetermined time (for example, 33 msec). However, the present invention is not limited to this, and a sensor for detecting a vehicle that enters the license plate recognition area 6 is installed, and while the sensor detects the vehicle, the photographing process is repeatedly executed every predetermined time. There may be.

  Referring to FIG. 3, in the photographing process, in step S <b> 1, photographing is performed by the plate recognition camera 3, and processing for monitoring the invasion of the vehicle into the license plate recognition area 6 based on the photographed photographed image is performed. Done. Thereby, imaging | photography with the plate recognition camera 3 is performed for every predetermined time (for example, 33 msec). Next, in step S2, a process for determining whether or not a license plate of a vehicle that has entered the license plate recognition area 6 has been found is performed. When it is determined that no discovery has been made, the process proceeds to step S1. On the other hand, when it is determined that it has been found, in step S3, processing for recognizing characters and numbers in the license plate is started.

  The processing of step S1 to step S3 is performed by the image analysis unit 51, the license plate recognition area entry determination unit 52, and the license plate information identification unit 53 included in the processing unit 20. Moreover, what is necessary is just to employ | adopt the method currently disclosed by the patent 2910130 gazette and Unexamined-Japanese-Patent No. 2000-99698 as the processing method of step S1-step S3, for example.

  In step S4, a process of determining whether or not the recognition result in the process started in step S3 satisfies a specific condition as compared with the license plate information stored in the monitored vehicle information storage unit 54. Is done. The process of step S4 is performed by the vehicle determination unit 55 included in the processing unit 20.

  For example, when the information stored in the monitored vehicle information storage unit 54 is “Kobe 11 a 4249”, a process of determining whether or not the recognition result matches “Kobe 11 a 4249” is performed. Further, when the information stored in the monitored vehicle information storage unit 54 is “249”, a process for determining whether or not the recognition result includes “249” in the serial number is performed.

  In step S4, based on the recognition result in the process started in step S3, it is determined whether or not a specific condition is satisfied in comparison with the license plate information stored in the monitored vehicle information storage unit 54. The example of performing the process is described, but before performing the process of step S3 and step S4, the narrowing process is performed to reduce the number of vehicles to be processed in step S3 and step S4, thereby reducing the processing burden. You may do it.

  As the narrowing-down process, for example, a process for recognizing the color of the vehicle is performed, and the color of the vehicle based on the recognition result in the process is compared with the color of the vehicle stored in the monitored vehicle information storage unit 54. If they match, the process from step S3 onward may be performed, and if they do not match, the process may move to step S6. As a processing method for recognizing the color of the vehicle, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2004-334665 may be adopted.

  If it is determined in step S4 that the condition is not satisfied, in step S6, a process is performed in which the image capturing camera 4 captures the image and the captured image is compressed at the first compression rate. On the other hand, if it is determined in step S4 that the image is satisfied, in step S5, the image capturing camera 4 captures the image and the captured image is compressed at a second compression rate lower than the first compression rate. Processing is performed. That is, in the process of step S5, the data amount is larger than that when the image is compressed at the first compression rate, but the image definition can be kept high. The processing in step S5 and step S6 is performed by the compression unit 56 included in the processing unit 20. The first and second compression rates may be stored in advance on the road processing device 5 side, or may be input and transmitted by input processing by the PC 42 on the central processing device 40 side. In the first embodiment, the example in which the compression process is performed at the second compression rate lower than the first compression rate in step S5 has been described. However, the present invention is not limited to this, and the compression process is performed. It may not be.

  As described above, when YES is determined in step S2 and YES is determined in step S4, the process in step S5 is performed. On the other hand, if YES is determined in step S2 and NO is determined in step S4, the process in step S6 is performed. Therefore, once it is determined as YES in step S4, a predetermined condition that is satisfied when the vehicle subject to the determination enters the monitoring area 7 and is determined as NO in step S2 or step S4 is satisfied. Until this is done, the process in step S5 is performed. The predetermined condition in this case refers to a condition that is established when the vehicle that is determined as YES in step S4 enters the monitoring area 7.

  The predetermined condition may be a condition that is satisfied when a predetermined time elapses after YES is determined in step S4. In this case, the predetermined time is a time sufficient for the vehicle to pass through the monitoring area 7.

  In step S7, the data for specifying the recognition result in the process started in step 3, the compressed image compressed in step S5 or step S6, and the photographed image photographed by the plate recognition camera 3 are used. Each of them is associated with each other and stored in the image storage unit 21 and transmitted to the central processing unit 40. The processing in step S7 is performed by the storage processing unit 57 and the communication unit 58 included in the processing unit 20. In the central processing unit 40, processing for storing the image transmitted from the road processing unit 5 in the storage unit 44 included in the server 41 is performed.

  In step S7 in the first embodiment, the example in which the compressed image already compressed in step S5 or step S6 is stored according to the determination in step S4 has been described. However, the present invention is not limited to this, and the captured image captured by the image capturing camera 4 is temporarily stored without being compressed, and then the determination in step S4 is performed and the compressed image is stored in step S5 or step S6. While being stored in the unit 21, processing to be transmitted to the central processing unit 40 may be performed.

  As described above, in the first embodiment, the second compression rate is set lower than the first compression rate. For this reason, when a vehicle satisfying a specific condition has entered the license plate recognition area 6, the captured image captured by the image capturing camera 4 is stored in the image storage unit 21 in a fine state. The data can be transmitted to the central processing unit 40 and stored in the storage unit 44. On the other hand, when a vehicle that does not satisfy a specific condition has entered the license plate recognition area 6, the captured image captured by the image capturing camera 4 is stored in the image storage unit 21 in a rough state and the center. The data can be transmitted to the processing device 40 and stored in the storage unit 44. Thereby, while being able to reduce the data amount of the image memorize | stored in the road processing apparatus 5 and the central processing unit 40, a fine image can be memorize | stored about a monitoring vehicle. The fine image in the first embodiment refers to an image stored one by one in a clear state.

  In the first embodiment, the first compression rate or the second compression is determined depending on whether or not the vehicle that has entered the license plate recognition area 6 satisfies a specific condition. The example of compressing the captured image captured by the image capturing camera 4 at the rate has been described. However, the present invention is not limited to this, and the resolution of the captured image captured by the image capturing camera 4 depends on whether or not the vehicle that has entered the license plate recognition area 6 satisfies a specific condition. The first resolution or the second resolution higher than the first resolution may be set. Specifically, when a vehicle that satisfies a specific condition has entered the license plate recognition area 6, the resolution of the captured image captured by the image capturing camera 4 is set to the second resolution. On the other hand, when a vehicle that does not satisfy the specific condition has entered the license plate recognition area 6, the resolution of the captured image captured by the image capturing camera 4 is set to the first resolution. Thereby, it is possible to store a fine image of the monitored vehicle in the road processing device 5 and the central processing device 40. In this case, a fine image means an image stored one by one in a clear state.

[Second Embodiment]
Next, a monitoring system in the second embodiment will be described. In the first embodiment described above, an example in which the compression rate of the captured image captured by the image capturing camera 4 varies depending on whether or not the specific condition is satisfied in step S4 of FIG. explained. In the second embodiment, an example in which the number of times the image capturing camera 4 captures images per unit time (imaging frequency) varies depending on whether or not a specific condition is satisfied in step S4 of FIG. explain. Hereinafter, the second embodiment will be described with respect to differences from the first embodiment, and the description overlapping with the first embodiment will not be repeated.

  The camera control unit 50 included in the processing unit 20 in the second embodiment controls the plate recognition camera 3 so as to capture an image a predetermined number of times per unit time. In addition, the camera control unit 50 controls the camera for controlling image capturing 4 so as to capture at least the first number of times or a second number of images larger than the first number of times per unit time. The first and second times may be stored in advance on the road processing device 5 side, or may be input and transmitted by input processing by the PC 42 on the central processing device 40 side.

  When it is determined in step S4 described with reference to FIG. 3 that the image is not satisfied, in step S6, instead of the process of compressing the captured image with the first compression rate, the camera control unit 50 performs image capturing. Processing is performed to control the camera 4 so as to shoot at the first number of times per unit time. On the other hand, when it is determined that the condition is satisfied in step S4, the camera replaces the process of compressing the photographed captured image with the second compression rate lower than the first compression rate in step S5 described in FIG. The control unit 50 performs processing for controlling the image capturing camera 4 to capture the image at the second number of times per unit time.

  In step S7 described in FIG. 3, the data for specifying the recognition result in the process started in step 3, the image photographed in step S5 or step S6, and the plate recognition camera 3 photographed. The captured image is associated with each other and stored in the image storage unit 21 and transmitted to the central processing unit 40.

  As described above, in the second embodiment, the second number is set larger than the first number. For this reason, when a vehicle that satisfies a specific condition has entered the license plate recognition area 6, a large number of images are captured by the image capturing camera 4, and the images are stored in the image storage unit 21. The data can be transmitted to the central processing unit 40 and stored in the storage unit 44. On the other hand, when a vehicle that does not satisfy a specific condition has entered the license plate recognition area 6, the image capturing camera 4 captures a small number of images and stores the images in the image storage unit 21. The data can be transmitted to the central processing unit 40 and stored in the storage unit 44. Thereby, while being able to reduce the data amount of the image memorize | stored in the road processing apparatus 5 and the central processing unit 40, a fine image can be memorize | stored about a monitoring vehicle. The fine image in the second embodiment refers to an image stored in a detailed state with a large number of sheets per unit time.

  The monitoring system 1 and the road processing device 5 may be a combination of the contents described in the first embodiment and the contents described in the second embodiment. For example, when it is determined in step S4 described with reference to FIG. 3 that the condition is not satisfied, in step S6, the camera control unit 50 controls the image capturing camera 4 to capture the first number of times per unit time. And a process of compressing the photographed photographed image at the first compression rate. If it is determined in step S4 that the condition is satisfied, in step S5 described with reference to FIG. 3, the camera control unit 50 controls the image capturing camera 4 to capture a second number of times per unit time. And a process of compressing a captured image captured by the image capturing camera 4 at a second compression rate lower than the first compression rate.

[Third Embodiment]
Next, a monitoring system in the third embodiment will be described. In the third embodiment, an example will be described in which the amount of light emitted toward the monitoring region 7 is varied depending on whether or not a specific condition is satisfied in step S4 of FIG. In the following, the third embodiment will be described with respect to differences from the first and second embodiments, and the description overlapping with the first and second embodiments will not be repeated.

  The casing 2 in the third embodiment further houses a flash device as a flash device that emits light toward the monitoring region 7. The flash device uses an infrared LED (Light Emitting Diode) as a flash light source. However, the present invention is not limited to this, and the flash device may be any type of light source. The flash device is connected to the road processing device 5.

  The processing unit 20 in the third embodiment further includes a light amount control unit 59 (see FIG. 2) that controls the amount of light emitted from the infrared LED of the flash device. The light amount control unit 59 controls the infrared LED to emit the first light amount or a second light amount larger than the first light amount in accordance with the timing when the camera control unit 50 captures an image with the image capturing camera 4. . The first and second light quantities may be stored in advance on the road processing device 5 side, or may be input and transmitted by input processing by the PC 42 on the central processing device 40 side.

  When it is determined in step S4 described with reference to FIG. 3 that the image is not satisfied, in step S6, the light amount control unit 59 replaces the process of compressing the captured image with the first compression rate, etc. To control to emit light with the first light quantity. On the other hand, when it is determined that the condition is satisfied in step S4, in step S5 described with reference to FIG. 3, instead of the process of compressing the captured image at a second compression rate lower than the first compression rate, etc. Processing for controlling the light amount control unit 59 to emit light with the second light amount from the infrared LED is performed.

  In step S7 described in FIG. 3, the data for specifying the recognition result in the process started in step 3, the image photographed in step S5 or step S6, and the plate recognition camera 3 photographed. The captured image is associated with each other and stored in the image storage unit 21 and transmitted to the central processing unit 40.

  As described above, in the third embodiment, the second light amount is set larger than the first light amount. For this reason, when a vehicle that satisfies a specific condition has entered the license plate recognition area 6, a relatively large amount of light is emitted from the infrared LED when an image is captured by the image capturing camera 4. be able to. On the other hand, when a vehicle that does not satisfy a specific condition has entered the license plate recognition area 6, a relatively small amount of light is emitted from the infrared LED when an image is captured by the image capturing camera 4. Can do. Thereby, a fine image of the monitoring vehicle can be stored in the road processing device 5 or the central processing device 40. A fine image in the third embodiment refers to an image stored one by one in a clear state.

  In addition, there has been a problem that the sharpness of an image photographed in the past is greatly influenced by the quality of the windshield. In the third embodiment, however, the amount of light when photographing a surveillance vehicle is increased. It is possible to stably shoot with a reduced adverse effect depending on the quality of the glass. Furthermore, in order to increase the amount of light when a vehicle that satisfies a specific condition has entered the license plate recognition area 6, the service life of the infrared LED is made longer than when shooting with always increasing the amount of light. can do.

  Note that the monitoring system 1 and the road processing device 5 may be a combination of the contents described in the first embodiment and the contents described in the third embodiment. For example, when it is determined that the condition is not satisfied in step S4 described with reference to FIG. 3, in step S6, the light amount control unit 59 performs a process of controlling the infrared LED to emit light with the first light amount, and for image shooting. You may comprise so that the process which compresses the picked-up image image | photographed with the camera 4 with the 1st compression rate may be performed. If it is determined in step S4 that the condition is satisfied, in step S5 described with reference to FIG. 3, the light amount control unit 59 performs processing for controlling the infrared LED to emit light with the second light amount, and for image shooting. You may comprise so that the process which compresses the picked-up image image | photographed with the camera 4 with the 2nd compression rate lower than a 1st compression rate may be performed.

  The monitoring system 1 and the road processing device 5 may be a combination of the contents described in the second embodiment and the contents described in the third embodiment. For example, when it is determined in step S4 described with reference to FIG. 3 that the condition is not satisfied, in step S6, the camera control unit 50 controls the image capturing camera 4 to capture the first number of times per unit time. In addition, the light amount control unit 59 may be configured to perform a process of controlling the infrared LED to emit light with the first light amount. If it is determined in step S4 that the condition is satisfied, in step S5 described with reference to FIG. 3, the camera control unit 50 controls the image capturing camera 4 to capture a second number of times per unit time. In addition, the light amount control unit 59 may be configured to perform a process of controlling the infrared LED to emit light with the second light amount.

  Similarly, the monitoring system 1 and the road processing device 5 may be a combination of all the contents described in the first to third embodiments.

[Fourth Embodiment]
Next, a monitoring system in the fourth embodiment will be described. In the fourth embodiment, when the specific condition is satisfied in step S4 of FIG. 3, the position of the windshield portion of the monitoring vehicle is predicted, and the windshield portion of the monitoring vehicle reaches the specific area. An example in which shooting is performed while the shooting magnification of the image shooting camera 4 is increased at the predicted timing will be described. Hereinafter, about a 4th embodiment, a different point from the 1st-3rd embodiment is explained, and explanation which overlaps with the 1st-3rd embodiment is not repeated.

  The camera control unit 50 included in the processing unit 20 in the fourth embodiment controls the imaging magnification of the image capturing camera 4 to at least the first magnification or the second magnification larger than the first magnification. The image capturing camera 4 can zoom and capture a specific area in the monitoring area 7 by the camera control unit 50 controlling the first magnification to the second magnification. The first and second magnifications may be stored in advance on the road processing device 5 side, or may be input and transmitted by input processing by the PC 42 on the central processing device 40 side.

  Further, the processing unit 20 is an image captured at the first timing by the plate recognition camera 3 when the vehicle determination unit 55 determines that the specific condition is satisfied from the image captured at the first timing. And an image photographed at a second timing after a lapse of a predetermined time from the first timing (when the camera controller 50 controls the plate recognition camera 3 to photograph every 33 msec). The feature point position calculation unit 60 (see FIG. 2) that extracts common feature points of the vehicle from the above and calculates the position of the feature point, and the first timing and the second timing calculated by the feature point position calculation unit 60 A moving distance calculation unit 61 (see FIG. 2) that calculates the moving distance of the feature point on the image per unit time from the difference in the position of the feature point in The arrival distance storage unit 62 (see FIG. 2) that stores the arrival distance on the image where the lath portion reaches the specific region, and the movement distance per unit time calculated by the movement distance calculation unit 61 and the arrival distance storage unit 62 are stored. Whether the arrival timing calculated by the arrival timing calculation unit 63 (see FIG. 2) and the arrival timing calculation unit 63 that calculates the arrival timing at which the windshield portion of the vehicle reaches the specific region from the reached arrival distance. An arrival timing determination unit 64 (see FIG. 2) for determining whether or not. The reach distance stored in the reach distance storage unit 62 is a fixed value stored in advance. For example, the windshield of the vehicle from the position extracted as the feature point on the image taken by the plate recognition camera 3 is used. A value corresponding to the average distance to the installed position. Here, as the reach distance, for example, 200 dots are stored as the reach distance from the center point of the number of the license plate to the center point of the windshield. This utilizes the fact that there is no significant difference between the position where the license plate is attached and the position where the vehicle windshield is attached, although it varies slightly depending on the vehicle type.

  The windshield portion of the vehicle photographed by the plate recognition camera 3 reaches the specific area by the feature point position calculation unit 60, the movement distance calculation unit 61, the reach distance storage unit 62, and the arrival timing calculation unit 63. The arrival timing can be specified. Then, the arrival timing determination unit 64 can specify whether or not it is the timing when the windshield portion of the vehicle reaches the specific region.

  For the processing method by the feature point position calculation unit 60 and the processing method by the movement distance calculation unit 61, for example, the methods disclosed in Japanese Patent Laid-Open Nos. 2001-126184 and 2004-326382 may be employed. Good. The feature points in the fourth embodiment are predetermined positions on the front side of the windshield portion in the vehicle, such as points and lines specified from letters and numbers arranged in the license plate, places where emblems are attached, etc. Anything may be used.

  Next, an example of a processing method by the arrival timing calculation unit 63 and the arrival timing determination unit 64 will be described. First, the arrival timing calculation unit 63 calculates a value obtained by dividing the arrival distance stored in the arrival distance storage unit 62 by the movement distance calculated by the movement distance calculation unit 61, and the second from the first timing. The arrival timing is calculated by multiplying the elapsed time (33 msec) until the timing. For example, if the arrival distance stored in the arrival distance storage unit 62 is 200 dots and the movement distance per unit time calculated by the movement distance calculation unit 61 is 10 dots, the arrival timing calculation unit 63 As a timing, (200/10) × 33 msec = 660 msec is calculated. Thereby, the arrival timing determination unit 64 can determine that the windshield portion of the vehicle has reached the specific area after 660 msec has elapsed from the first timing. In this way, it is possible to specify the arrival timing at which the windshield portion of the vehicle photographed by the plate recognition camera 3 reaches the specific area.

  As will be described later, the camera control unit 50 controls the imaging magnification of the image capturing camera 4 to the second magnification when the arrival timing is reached, and zooms and captures a specific area in the monitoring area 7.

  Next, photographing processing for performing photographing by the plate recognition camera 3 and the image photographing camera 4 and compression of the photographed image in the road processing device 5 of the fourth embodiment will be described. FIG. 4 is a flowchart for explaining processing at the time of shooting in the fourth embodiment.

  Referring to FIG. 4, in the shooting process in the fourth embodiment, after determining that the condition set in step S4 is satisfied, it is determined in step S401 that the set condition is satisfied. A process for determining whether or not this is the second time is performed. For example, when the monitoring vehicle has entered the license plate recognition area 6, the vehicle determination unit 55 continuously determines that the specific condition is satisfied in step S4. The second determination that the set condition described in the process of step S401 is satisfied this time means the second determination among those that are continuously determined to satisfy the set condition. . When it is determined that the condition is not satisfied, the process proceeds to step S407 described later.

  On the other hand, when it is determined that the condition is satisfied, in step S402, the feature point position calculation unit 60 extracts a common feature point of the vehicle based on the image taken before the predetermined time and the image taken this time, and the feature point is extracted. Processing for calculating the position of is performed. In step S403, a process for calculating a movement distance per unit time from the difference between the positions of the feature points calculated by the feature point position calculation unit 60 by the movement distance calculation unit 61 is performed.

  Next, in step S <b> 404, a process of reading the reach distance stored in the reach distance storage unit 62 is performed. Further, in step S405, the windshield portion of the vehicle is set to a specific area from the movement distance per unit time calculated by the movement distance calculation unit 61 by the arrival timing calculation unit 63 and the arrival distance read from the arrival distance storage unit 62. Processing for calculating the arrival timing to be reached is performed, and the process proceeds to step S407. As described above, the processes in steps S402 to S405 are executed when YES is determined in step S401. For this reason, NO is determined in step S401 for the third and subsequent times that are continuously determined to satisfy the set condition. Thereby, it is possible to prevent the process for calculating the arrival timing described in steps S402 to S405 from being repeated many times for the same vehicle.

  Processing regarding whether or not the arrival timing calculated in step S405 has been reached is performed in step S407. If it is determined in step S407 that the arrival timing has been reached, in step S408, the camera control unit 50 controls the imaging magnification of the image capturing camera 4 from the first magnification to the second magnification to perform imaging. As a result, the image capturing camera 4 can zoom and photograph the windshield portion of the monitoring vehicle that is predicted to reach a specific area in the monitoring area 7, and can capture a captured image of the passenger of the monitoring vehicle. Obtainable.

  On the other hand, when it is determined in step S4 that it has not been satisfied, or when it is determined in step S407 that the arrival timing has not been reached, in step S409, the camera control unit 50 sets the imaging magnification of the image capturing camera 4 to the first. Shooting is controlled at a magnification of 1. In step S410, a process of compressing the photographed image photographed at a predetermined magnification in step S408 or S409 at a predetermined compression rate is performed, and the process proceeds to step S7.

  As described above, in the fourth embodiment, a larger magnification than the first magnification is set as the second magnification. For this reason, when a vehicle satisfying a specific condition has entered the license plate recognition area 6 and when the arrival timing at which the windshield portion of the vehicle reaches the specific area is reached The camera 4 can be zoomed to photograph a specific area, and the image can be stored in the image storage unit 21 and transmitted to the central processing unit 40 and stored in the storage unit 44. Thereby, a fine image of the monitoring vehicle can be stored in the road processing device 5 or the central processing device 40. The fine image in the fourth embodiment refers to an enlarged image obtained by pinpointing the windshield portion of the monitoring vehicle.

  The monitoring system 1 and the road processing device 5 may be a combination of the contents described in the fourth embodiment and the contents described in the first embodiment. For example, after the camera control unit 50 controls the imaging magnification of the image capturing camera 4 from the first magnification to the second magnification in step S408 described with reference to FIG. 4, the captured image is captured in step S410. You may comprise so that the process (it is the same as step S5 of FIG. 3) compressed with a 2nd compression rate may be performed. In addition, after NO is determined in step S407 described with reference to FIG. 4, the process proceeds to step S409 and the photographed image is compressed at the second compression rate (similar to step S5 in FIG. 3) without proceeding to step S409. It may be configured to perform only. Furthermore, after the camera control unit 50 controls the imaging magnification of the image capturing camera 4 to the first magnification in step S409 described with reference to FIG. 4, the captured image is converted to the first compression rate in step S410. May be configured to perform the compression process (similar to step S6 in FIG. 3).

  Similarly, as the monitoring system 1 and the road processing device 5, the contents described in the fourth embodiment are selectively combined with the contents described in each of the first to third embodiments. Also good.

[Fifth Embodiment]
Next, a monitoring system in the fifth embodiment will be described. In the above-described fourth embodiment, the timing at which the windshield portion of the monitoring vehicle reaches the specific area when the specific condition is satisfied in step S4 of FIG. An example of shooting with increasing shooting magnification has been described. In the fifth embodiment, when a specific condition is satisfied in step S4 of FIG. 3, an image is taken according to whether or not the specific area has been reached by specifying the windshield portion of the monitored vehicle. An example in which shooting is performed by increasing the shooting magnification of the camera 4 will be described. Hereinafter, the fifth embodiment will be described while referring to differences from the fourth embodiment, and the description overlapping with the fourth embodiment will not be repeated.

  The housing 2 in the fifth embodiment further stores thermopiles 31 and 32 having their light receiving parts directed in the direction of the specific area in the monitoring area 7. Each of the thermopiles 31 and 32 is connected to the road processing device 5. Here, the thermopile is an infrared sensor that generates thermal electromotive force according to the amount of energy when receiving infrared rays radiated from individual objects in a non-contact manner. The amount of energy is proportional to the fourth power of the absolute temperature and the emissivity of the object in the thermopile field of view (see Stefan-Boltzmann equation).

  As the thermopile 31 in the fifth embodiment, one that absorbs only infrared rays having a wavelength of 8 μm to 10 μm is used. The thermopile 31 may be provided with a filter that transmits only wavelengths between 8 μm and 10 μm. Moreover, the thermopile 32 uses what absorbs only the infrared rays whose wavelength is between 10 micrometers-12 micrometers. The thermopile 32 may be provided with a filter that transmits only a wavelength between 10 μm and 12 μm.

  Here, the features of the thermopiles 31 and 32 will be described. FIG. 5 is a diagram for explaining an output voltage output from the thermopile 31 or 32 in accordance with the part of the vehicle 9 that enters the field of view of the thermopile 31 or 32. FIG. 5A shows the viewing direction of the thermopiles 31 and 32 by solid lines. The state of FIG. 5A shows that the windshield portion of the vehicle 9 is in the field of view of the thermopiles 31 and 32.

  In FIG. 5 (b), the vertical axis represents the output voltage and the horizontal axis represents time, and the output voltage output from the thermopile 31 corresponding to the part of the vehicle 9 in the field of view is output from the thermopile 32 as a solid line. Each output voltage is indicated by a thick dotted line.

  Sections after T0 to T1 and T4 shown in FIG. 5B indicate output voltages when the vehicle 9 is not in the field of view of the thermopiles 31 and 32 shown in FIG. The output voltage from the thermopile 31 indicates V2, and the output voltage from the thermopile 32 indicates V3.

  The section of T1 to T2 and T3 to T4 shown in FIG. 5 (b) is from the portion from the front side (front end) of the vehicle 9 to the windshield in the field of view of the thermopile 31 and 32 shown in FIG. The output voltage when the rear (rear end) portion is included is shown. The output voltage from the thermopile 31 indicates V4 higher than V2, and the output voltage from the thermopile 32 indicates V6 higher than V3.

  The section from T2 to T3 shown in FIG. 5 (b) shows the output voltage when the windshield portion of the vehicle 9 is in the field of view of the thermopile 31, 32 shown in FIG. 5 (a). The output voltage from the thermopile 31 shows V1 that is extremely lower than V4, and the output voltage from the thermopile 32 shows V5 that is slightly lowered from V6, unlike the sudden change in the output voltage of the thermopile 31.

  As shown in FIG. 5, the thermopile 31 has an extremely low output voltage when the windshield enters the field of view, and the thermopile 32 does not have a very low output voltage even when the windshield enters the field of view. . In the fifth embodiment, a windshield portion of a vehicle, which will be described later, is detected by using such features of the thermopiles 31 and 32 and a feature in which infrared radiation intensity differs between the windshield and other materials. Processing is performed.

  The processing unit 20 in the fifth embodiment includes a ratio calculation unit 65 that calculates a ratio used to specify the windshield portion of the vehicle, and whether the ratio calculated by the ratio calculation unit 65 is equal to or less than a predetermined value. A ratio determining unit 66 for determining The ratio calculation unit 65 calculates the ratio between the output voltage from the thermopile 31 and the output voltage from the thermopile 32 before the camera control unit 50 captures images with the image capturing camera 4.

  Next, photographing processing for performing photographing by the plate recognition camera 3 and the image photographing camera 4 and compression of the photographed image in the road processing device 5 according to the fifth embodiment will be described. FIG. 6 is a flowchart for explaining the photographing process in the fifth embodiment.

  Referring to FIG. 6, in the shooting process in the fifth embodiment, after it is determined that the condition set in step S4 is satisfied, in step S501, ratio calculation unit 65 starts from thermopile 31, 32. Based on the output voltage, the ratio of the output voltage from the thermopile 31 to the output voltage from the thermopile 32 is calculated. In step S502, the ratio determining unit 66 performs a process of determining whether or not the ratio calculated by the ratio calculating unit 65 is equal to or less than a predetermined value. If it is determined in step S502 that the ratio is equal to or less than the predetermined value, in step S503, the camera control unit 50 controls the imaging magnification of the image capturing camera 4 from the first magnification to the second magnification to perform imaging. As described above, in the fifth embodiment, the area including the windshield is enlarged and photographed based on the windshield, other materials, and the intensity change of infrared rays. As a result, the image capturing camera 4 can zoom and capture the windshield portion of the monitoring vehicle that has reached the specific area in the monitoring area 7, and can obtain a captured image that captures the passenger of the monitoring vehicle. .

  On the other hand, when it is determined in step S4 that the ratio is not satisfied, or when it is determined in step S502 that the ratio is not less than or equal to the predetermined value, the camera control unit 50 sets the imaging magnification of the image capturing camera 4 to the first in step S504. Shooting is controlled at a magnification of. In step S505, a process of compressing the captured image captured at a predetermined magnification in step S503 or S504 at a predetermined compression rate is performed, and the process proceeds to step S7.

  As described above, in the fifth embodiment, a magnification larger than the first magnification is set as the second magnification. For this reason, when a vehicle that satisfies a specific condition has entered the license plate recognition area 6 and the windshield portion of the vehicle reaches the specific area, the camera 4 for image capturing is zoomed. Thus, the windshield portion of the monitoring vehicle in the specific area can be photographed, and the image can be stored in the image storage unit 21 and transmitted to the central processing unit 40 and stored in the storage unit 44. Thereby, a fine image of the monitoring vehicle can be stored in the road processing device 5 or the central processing device 40. The fine image in the fifth embodiment refers to an enlarged image obtained by pinpointing the windshield portion of the monitoring vehicle.

  In the fifth embodiment, it is determined whether or not the windshield portion of the monitoring vehicle has reached the specific area, and the specific area is zoomed and photographed when it is determined that the specific area has arrived. Explained. However, the present invention is not limited to this, and the position of the windshield portion of the monitoring vehicle may be detected, and the detected position may be zoomed and photographed.

  The monitoring system 1 and the road processing device 5 may be a combination of the contents described in the fifth embodiment and the contents described in the first embodiment. For example, after the camera control unit 50 controls the imaging magnification of the image capturing camera 4 from the first magnification to the second magnification in step S503 described with reference to FIG. 6, the captured image is displayed in step S505. You may comprise so that the process (it is the same as step S5 of FIG. 3) compressed with a 2nd compression rate may be performed. Further, after NO is determined in step S502 described with reference to FIG. 6, the process proceeds to step S505 without compressing the captured image at the second compression rate (similar to step S5 in FIG. 3). It may be configured to perform only. Further, after the camera control unit 50 controls the imaging magnification of the image capturing camera 4 to the first magnification in step S504 described with reference to FIG. 6, the captured image is converted to the first compression rate in step S505. May be configured to perform the compression process (similar to step S6 in FIG. 3).

  Similarly, as the monitoring system 1 and the road processing device 5, the contents described in the fifth embodiment are selectively combined with the contents described in each of the first to third embodiments. Also good.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a perspective view which shows typically a part of road used as the object of the monitoring by a monitoring system. It is a control block diagram of a monitoring system. It is a flowchart for demonstrating the process at the time of imaging | photography. It is a flowchart for demonstrating the process at the time of imaging | photography in 4th Embodiment. It is a figure for demonstrating the output voltage output from a thermopile according to the site | part of the vehicle which entered the visual field of the thermopile. It is a flowchart for demonstrating the process at the time of imaging | photography in 5th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Surveillance system, 2 housing | casing, 3 plate recognition camera, 4 imaging camera, 5 road processor, 6 license plate recognition area, 7 monitoring area, 9 vehicle, 10 road, 20 processing part, 21 image storage part, 31, 32 Thermopile, 40 Central processing unit, 41 Server, 42 PC.

Claims (9)

A discriminating means for discriminating whether or not the license plate of the vehicle passing through the monitoring area is a specific license plate satisfying a specific condition, based on a captured image obtained by capturing the monitoring area through which the vehicle passes;
A light emitting means for emitting light toward the monitoring area,
The light emitting means emits light with an increased amount of light when it is during a predetermined period after it is determined that the determining means is the specific license plate than when it is not during the predetermined period. apparatus. Further comprising an image compression means for compressing the pre-Symbol captured image,
Said image compression means, pre-captured images in the inter Kisho periodically, characterized by compressing at a compression ratio lower than the photographed image when it is not in the predetermined period, the monitoring device according to claim 1. It further comprises photographing frequency control means for controlling the photographing frequency for photographing the photographed image,
The monitoring apparatus according to claim 1, wherein the imaging frequency control unit increases the imaging frequency when the predetermined period is in progress than when not in the predetermined period. Further provided is a photographing magnification control means for controlling a photographing magnification for photographing the photographed image,
4. The method according to claim 1, wherein the photographing magnification control means shoots an enlarged region including a windshield when the predetermined period is in effect and when not during the predetermined period. 5. A monitoring device according to the above. Feature point extracting means for extracting feature points of the vehicle based on the captured image;
A moving distance calculating unit that calculates a distance that the characteristic point extracted by the characteristic point extracting unit has moved while a predetermined time elapses in the captured image;
5. The imaging magnification control unit according to claim 4, wherein the imaging magnification control unit performs imaging by enlarging an area including the windshield based on the feature point and the distance calculated by the moving distance calculation unit. Monitoring device. Infrared detection means for detecting infrared rays of a predetermined wavelength from the monitoring area,
The monitoring apparatus according to claim 4, wherein the photographing magnification control unit magnifies and captures an area including the windshield based on an infrared intensity change detected by the infrared detection unit. Further comprising resolution setting means for setting the resolution of the captured image;
The monitoring apparatus according to claim 1, wherein the resolution setting unit sets a higher resolution when the predetermined period is in progress than when not during the predetermined period. A monitoring system comprising a monitoring device that monitors a monitoring area through which a vehicle passes, and a management device that manages images from the monitoring device,
The management device
License plate information input means for inputting information relating to the license plate of the vehicle;
License plate information transmitting means for transmitting the information input by the license plate information input means to the monitoring device;
The monitoring device
Information storage means for storing information transmitted from the license plate information transmission means;
Light emitting means for emitting light toward the monitoring area;
And transmission means for transmitting the captured image captured the monitoring area in front Symbol management device,
The management device
A management device-side image storage unit that stores the captured image transmitted by the transmission unit;
The monitoring device
Based on the captured image, the vehicle further includes a determination unit that determines whether the license plate of the vehicle passing through the monitoring area is a specific license plate that satisfies a specific condition,
The light emitting means emits light with an increased amount of light when it is during a predetermined period after it is determined that the determining means is the specific license plate than when it is not during the predetermined period. system. A determination step of determining whether or not the license plate of the vehicle passing through the monitoring area is a specific license plate that satisfies a specific condition, based on a captured image obtained by capturing the monitoring area through which the vehicle passes;
A control step of controlling a light emitting means for emitting light toward the monitoring area ,
The control step controls the light emitting means to emit light with an increased amount of light when it is during a predetermined period after it is determined that the determination step is the specific license plate than when it is not during the predetermined period. A monitoring method comprising the steps of:

Images