KR20200126690A - Vehicle registration plate perception camera system - Google Patents

Abstract

The present invention relates to a camera system for clear license plate recognition. The present invention includes: at least one camera photographing and transmitting a license plate with a lens unit (L) formed that incorporates an optical lens and a filter switch unit including a polarization filter and a blocking filter blocking the visible light or infrared ray passing through the optical lens; an image sensor detecting the image captured by the lens unit (L); image processing means having an image output port for image information output to an external image display device and incorporating an image processing unit performing image processing by receiving a converted digital signal from the image sensor and an image collection unit performing image compression by receiving the processed image signal and storing the compressed image; a remote control center including a control server connected to the camera through a wired/wireless network and controlling the camera, an image storage server, an image display unit, and a management server managing the control server, the storage server, and the display unit; and a control unit controlling the image processing means and connected to an infrared projector so that visible light is blocked and an infrared ray is transmitted when the camera performs nighttime imaging.

Description

Vehicle registration plate perception camera system

The present invention relates to a vehicle license plate recognition camera system, and more particularly, to a vehicle license plate recognition camera system for obtaining a clear image of a license plate that is not clearly captured due to weather conditions such as fog or fine dust.

In general, a camera such as CCTV refers to a TV method that transmits images to a specific recipient, and has a variety of uses such as industrial, educational, medical, traffic control surveillance, disaster prevention, and internal image information transmission. It is also called a closed circuit TV because it connects transmission/reception by wire or wirelessly and cannot receive it arbitrarily except for the receiving object.

In recent years, installations for crime prevention are increasing, especially by installing CCTVs in bad offense areas such as alleys. The rapid increase in the installation of such CCTVs is the effect of preventing and deterring crimes, the ease of discovery and arrest of criminals, reduction of fear of crimes perceived by citizens, and supplementation of limited police personnel due to installation in major areas. This is because is empirically proven.

However, it is common to continuously operate CCTVs as described above throughout the day and night, and there have been cases where the quality of CCTV screens is influenced by variables such as weather. For example, if the day is blurred due to a lot of fine dust in recent years, or due to difficulty in viewing minutes due to heavy rain or fog, reflection of lights from vehicles, and neon signs in downtown areas, CCTV cannot properly display clear and clear image quality on the screen. There has been a problem that it becomes an obstacle in playing the role and function.

In addition, in light of the current reality that automobiles are becoming more popular, automobiles are commonly used in events such as crimes and traffic accidents. At this time, tracking the license plate of the vehicle and capturing clues becomes a very important clue in solving the crime. .

However, the surrounding CCTV or signals or speed cameras installed at four streets of highways or general roads do not have proper image quality when the weather such as heavy fog is not good, so even if the license plate of the vehicle is photographed, the license plate can be read properly. There were many cases where I could not do it.

Korean Patent Publication No. 2008-0010475 Korea Patent Publication No. 2014-0112337 Korean Patent Application No. 2004-0068098 Korean Patent Publication No. 2006-0073554

Therefore, the present invention was devised to solve this problem, regardless of day and night, even in the presence of fine dust, heavy rain, fog, reflection of vehicle lights, miscellaneous light, etc., the enforcement camera or the like captures and acquires a clear image of the license plate. It relates to a license plate recognition camera system for the purpose of being able to clearly read.

In addition, it is intended to provide a vehicle license plate recognition camera system capable of clearly photographing the license plate by applying a method of receiving image information and processing the image even for vehicles in which the license plate location is not constant.

In order to achieve this object, the present invention is a vehicle license plate recognition camera system, an optical lens and a lens unit having a built-in filter switching unit consisting of a blocking filter and a polarizing filter that blocks infrared and reflected or visible light passing through the optical lens. At least one camera that photographs and transmits the license plate, an image sensor that detects an image image captured from the lens unit, and an image processing unit that receives and processes a digital signal converted from the image sensor and applies the processed image signal. The camera is connected to the camera through a wired/wireless network and an image processing means having an image output port for outputting the image information to an external image display device, and a built-in image collection unit for compressing the received image and storing the compressed image. A remote control center consisting of a number recognition server and a management server using a remote control center and the image processing means, and an infrared emitter for transmitting infrared rays by blocking visible light when the camera is photographed at night. It characterized in that it includes.

In addition, the filter switching unit is characterized in that the color image is generated by blocking infrared and reflected light by transmitting visible light during the day, and transmitting the infrared light by blocking visible light at night to generate a black and white image.

In addition, the image collection unit recognizes the position of the license plate from the image of the stored vehicle, and the number recognition unit recognizes the character of the license plate from the image of the vehicle license plate recognized by the position recognition unit and measures the size of the recognized character. It characterized in that it comprises a server.

In addition, the camera is characterized in that the illuminance sensor is formed to measure and detect the illuminance of the predetermined area and transmits it to the image processing means.

Accordingly, the present invention is a vehicle license plate recognition camera system using a lens from which reflected light that interferes with the field of view is removed. Even in places with strong reflected light such as leaves, glass, vehicle lights, and above the water surface, which makes it difficult to identify the vehicle number on highways or general roads. It has the effect of securing clear and clean license plate photography.

In addition, since the camera blocks the visible light and photographs only infrared rays so as to obtain a clearer image by blocking unnecessary light rays, there is an effect of attenuating the light caused by the headlight of the vehicle in the visible light band.

In addition, even when the license plate attachment position of the entered vehicle is out of the general range, it is also possible to recognize the vehicle number by extracting the image of the vehicle license plate by clearly detecting this.

1A is an overall configuration diagram of a vehicle license plate recognition camera system according to the present invention.
1B is a configuration diagram of a camera.
2 is a photograph showing the concept of a polarizing lens.
3 is a block diagram of an image processing means.
4 is a configuration diagram showing a connection relationship between a camera, a management server, and a number recognition server.
5 is a comparative picture of a picture taken without polarization treatment and a picture taken after polarization treatment.
6 is a flow chart showing blocking and transmission of infrared and visible rays by a filter switching unit divided according to day and night.
7 is a view showing a vehicle license plate in a conventional manner.
Fig. 8 is a diagram showing a license plate imprinting using the system of the present invention.
9 is a flowchart of a license plate recognition algorithm using the camera of the system of the present invention.
10 is a detailed flowchart of an algorithm for recognizing a license plate using the camera of the system of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to elements of each drawing, it should be noted that the same elements have the same numerals as possible, even if they are indicated on different drawings.

In addition, in the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1A is an overall configuration diagram of a vehicle license plate recognition camera system according to the present invention, FIG. 1B is a configuration diagram of a camera, FIG. 2 is a photograph showing the concept of a polarizing lens, and FIG. 3 is a configuration diagram of an image processing means, 4 is a configuration diagram showing the connection relationship between the camera and the management server and the number recognition server, FIG. 5 is a comparison photo of a photograph taken without polarization treatment and a photograph taken after polarization treatment, and FIG. 6 is It is a flow chart showing the blocking and transmission of infrared and visible light by the divided filter switching unit, and FIG. 7 is a diagram showing that the license plate of the vehicle is photographed in a conventional manner, and FIG. 8 is the photographing of the license plate using the system of the present invention 9 is a flowchart of a license plate recognition algorithm using a camera of the system of the present invention, and FIG. 10 is a detailed flowchart of a license plate recognition algorithm using a camera of the system of the present invention.

As shown in FIG. 1A, the vehicle license plate recognition camera system C of the present invention includes a lens unit L, which is a polarizing lens unit in which an optical lens 5 and a filter switching unit 10 are built, and a captured image At least one camera 20 is formed to transmit. The camera 20 may be installed at any place where the license plate of the vehicle is to be photographed at a location such as a highway or a four-way street of a general road.

It is preferable that the camera 20 has a function of panning, tilting, and zooming with a control signal from a control server (not shown) configured to be built in the management server 61 so as to be able to be adjusted in the photographing direction.

Referring to FIG. 1B, the filter switching unit 10 which is a component of the lens unit L includes an infrared cut filter 11a and a visible light cut filter for blocking infrared or visible rays passing through the optical lens 5 11b). The infrared cut filter 11a, the visible light cut filter 11b, and a polarizing filter (not shown) capable of removing reflected light are also included.

The filter switching unit 10 transmits visible light during the day and blocks infrared and reflected light so that the image of the camera 20 generates a color image, and blocks visible light at night to transmit infrared light to generate a black and white image. To do it.

In addition, the lens unit (L) includes an illuminance sensor (S) formed in front of the camera 20 to adjust the brightness, and the illuminance sensor (S) is set as a certain area, and the illuminance of an area to be photographed or monitored. It detects and measures and generates an illuminance value, and transmits the generated illuminance value to the image processing means 40. Then, the image processing means 40 is connected to the communication unit 90 and transmits to the management server 61 as shown.

The image sensor 30 is an image pickup device that detects an image image captured (photographed) from the lens unit L, and functions to convert light into a digital signal after generating an analog signal. As an assembly of diodes, a CMOS imaging sensor or a CCD imaging sensor that converts light into electrical signals would be desirable.

In other words, it takes an image of a corresponding area, converts it into a digital image signal, and transmits it to the controller 70. Furthermore, the control unit 70 also serves to control the optical lens 5 and adjust the focus (focus).

The lens unit L shown in FIGS. 1A and 1B is a lens that removes reflected light that interferes with the field of view, as shown in FIG. 2, and is clearer in places where reflected light such as leaves, glass, vehicle light, or above the water is strong. And make it clear.

Referring to FIG. 3, an image processing means 40 is formed that receives and processes a digital image signal converted from the image sensor 30 described above.

As shown, the image processing unit 40 includes an image processing unit 41 and an image collection unit 42 that receives the processed image signal and compresses the image and stores the compressed image.

The image processing includes noise removal and balance adjustment. In addition, the image collection unit 42 receives the processed image signal from the image processing unit 41 and stores it in a secure digital card (SD Card).

The image processing means 40 compresses the image information transmitted from the image sensor 30 with a codec such as H-265, H-264, MPEG-4, MPEG, etc., and stores and transmits it.

In addition, the image processing means 40 transmits the image information to a management server 61 remotely through a network through an external communication unit 90.

In addition, the image processing means 40 may determine the state of the surveillance area of the camera 20 as day or night in consideration of the value of the illuminance transmitted from the illuminance sensor S, and the lens unit L It is possible to determine whether to control the image sensor 30 during shooting.

In addition, the image processing means 40 supplies power to the image processing unit 41, the image collection unit 42, and the image output port 43 for outputting image information to an external image display device (not shown). The power module 45 is included to provide power from the outside. However, the power module 45 is provided with a built-in battery in case of an emergency situation such as a power outage, and is supplied with power from the built-in battery. It is desirable to be configured to be able to deliver in configuration.

At this time, the power module 45 may be provided with a self-generation means for generating power from natural energy such as wind power or sunlight, and in the case of the built-in battery, a secondary battery is applied to be charged from the self-powered means in real time. Can be.

The power module 45 is composed of a secondary battery, the built-in battery 46 charged from the power source of the camera 20 and the sensing unit 47 and the sensing unit ( When it is determined that the supplied power is abnormal as a result of detection by 47), a power control unit 48 may be included to control the power of the built-in battery 46 to be supplied to each component.

That is, the power module 45 can detect a state in which power supply is interrupted or unstable, such as a power outage, and in this case, the power of each component can be activated with the power of the internal battery 46, which is its own battery. .

In addition, the control unit 70 controls the image processing means 40 as shown in Figs. 1A and 1B, and the camera 20 blocks visible light when photographing at night to transmit infrared rays. ) Is connected and formed.

In addition, the image collection unit 42 recognizes the character of the license plate from the position recognition unit 42a for recognizing the position of the license plate in the stored image of the vehicle and the image of the vehicle license plate recognized by the position recognition unit 42a, It includes a number recognition server (V) that measures the size of the recognized characters.

Furthermore, the image processing unit 41 interlocks with the number recognition server V that recognizes the vehicle license plate recognized by the location recognition unit 42a and the characters of the license plate.

Hereinafter, the relationship between the camera 20 and the management server 61 interconnected via a wired or wireless network will be described with reference to FIG. 4. It is preferable that the management server 61 and the camera 20 are formed to be connected to the communication unit 90 through a network to enable mutual signal transmission.

As shown, the management server 61 is connected to a plurality of cameras 20 through a wired/wireless network, and a control server (not shown) for controlling the camera 20 and a storage server (not shown) for storing images And a display unit (not shown) that displays the image. Accordingly, it manages the control server, the storage server, and the display unit.

In addition, the camera 20 and the number recognition server (V) of the image collection unit 42 is connected to the network by wired or wireless, and as shown, the camera 20 is connected to the camera 20 through a wired or wireless network, and the camera 20 The image of the license plate taken in is transmitted and stored through a built-in storage unit (not shown), and it is also possible to search for the license plate the person wants to find.

Hereinafter, the management server 61 will be described in detail.

The management server 61 is a wired/wireless network-based management server, and serves to convert images into a database and to issue an image storage command to an internal storage server. In addition, through the built-in control server, the overall camera operation such as zoom in and out of the camera 20, pan tilt, etc. is controlled, and the output screen of the built-in display unit is also controlled.

In addition, the storage server serves to store images captured by the camera 20. Therefore, the video recorded later can be retrieved later and replayed again.

In addition, the display unit selectively displays information including the location of the camera 20 and an image captured by the camera 20.

That is, the vehicle license plate recognition camera system (C) of the present invention applies a polarizing filter, blocks ultraviolet rays in sunny weather, and blocks unnecessary light rays in dark nights. Since it is provided, it can be photographed in accordance with the climate or meteorological characteristics of the region, and as shown in FIG. 5, it can be expressed as a picture on the right of a picture that is much clearer than the picture on the left before polarization treatment.

Hereinafter, a flowchart showing an operation relationship of the vehicle license plate recognition camera system C according to the present invention will be described with reference to FIG. 6.

Referring to FIG. 6, as cameras 20 installed in a certain area operate, a shooting area is designated, and the camera 20 prepares for image shooting including the location and direction of the designated area. (Step 1)

In the next step, the illuminance is measured by the illuminance sensor S formed in the camera 20, and day and night are distinguished through the contrast of light. (Second step)

That is, the illuminance sensor S, which has determined day and night, notifies the filter switching unit 10 of the lens unit L.

In the case of bright daytime, that is, during the daytime, the infrared cut filter 11a of the filter switching unit 10 blocks ultraviolet rays or infrared rays and transmits visible rays so that an image can be clearly displayed. (Step 3)

In the third step, by blocking ultraviolet rays or infrared rays, glare is prevented so that sunlight does not reflect on buildings, so that images with clearer image quality can be displayed. It allows color images to appear through visible light.

On the contrary, when the light is dark, the visible light blocking filter 11b of the filter switching unit 10 transmits infrared rays and blocks visible light so that a black and white image can be displayed. (Step 3)

Accordingly, since it is possible to eliminate reflections of vehicle lights or miscellaneous lights in the dark at night as a whole, there is an excellent advantage of improving image quality.

Therefore, in the case of shooting according to the conventional method as shown in FIG. 7, it is difficult to shoot the enforcement camera (with reference numerals omitted) downward at an angle of 15° to 30° from a pole 6m or more above the ground in order to avoid glare such as vehicle headlights. There was this.

However, as shown in FIG. 8, by operating the filter switch 10, which is one of the constituent elements of the present invention, the camera to which the vehicle license plate recognition camera system C of the present invention is applied is photographed by factors such as vehicle headlights from the front. Since the cause of the disturbance can be eliminated, there is an excellent effect of being able to take a clear image from any angle.

Therefore, the vehicle license plate recognition camera system (C) of the present invention captures the license plate of the vehicle clearly and clearly, regardless of the conditions of the weather or climate, and thus, night and daytime, reflection or glare of sunlight, headlights, fine Since it is possible to solve the problem that the camera cannot read the license plate of the vehicle due to the thick of dust, it is possible to implement a camera system that is optimal for photographing the license plate of the vehicle.

Hereinafter, with reference to the drawings, a license plate position detection and recognition algorithm that can be applied even when it is difficult to obtain the effect of a license plate photographing control due to different positions of the license plate by the vehicle license plate recognition camera system (C) according to the present invention will be described. To

9 is a flowchart of a license plate position detection and recognition algorithm using the license plate recognition camera system (C) of the present invention. As shown, the vehicle license plate recognition method according to the present invention includes a license plate multi-photographing step 100, a license plate region extraction step 200, a license plate image correction step 300, an individual character division step 400, and a license plate character recognition step. (500), data collection step (600); may be performed, including.

In the vehicle license plate recognition method using the license plate recognition camera system (C) according to the present invention, the on-board method, which is the current vehicle license plate recognition method, is not recognized when a vehicle enters outside of an unregistered character or camera angle. In order to improve the problem, the camera 20 is configured and installed as an IP camera, and a method of transmitting image information to a server for image processing is applied.

For reference, when explaining the IP camera, it is a camera used by connecting to the wired and wireless Internet. It is composed of a camera module, a decoder, an image compression chip, a CPU, and a network transmission chip, and the analog signal received from the camera module is digital through an encoder. It is characterized by having a flow transmitted through compression in a compression chip.

Therefore, by dividing the area of the vehicle license plate with three or more cameras 20, a vehicle image is captured, and an algorithm for recognizing the vehicle license plate by collecting the vehicle number obtained from each image is prepared to improve license plate recognition performance.

10 is a detailed flowchart of a license plate position detection and recognition algorithm in a vehicle image. As shown in FIG. 10, the method for recognizing a vehicle license plate of the camera system C according to the present invention,

The license plate multi-photographing step 100 is a step in which a plurality of IP cameras installed at various heights and angles divides the license plate by region and shoots it, and transmits the image information to the management server 61. (110), including a photographed image server transmission step (111).

The license plate region extraction step 200 is characterized in that the license plate region is extracted by detecting the position and color component of the license plate from the photographed image data.

The license plate image correction step 300 is characterized in that it comprises a filtering process for removing noise and improving the filtered image of the license plate image obtained in the license plate region extraction step 200, and a filtering step for removing noise (310), comprising a step 311 correcting the filtered image.

In the individual character division step 400, the image data corrected in the license plate image correction step 300 is converted to a binary image, and the binary image is divided into individual characters of the license plate based on the character string arrangement information according to the license plate shape. Character unit division is extracted through the character unit and each divided character is extracted into individual character blobs to be recognized. Step 410 of converting to a binary image, step of character unit division 411 ), and an individual character blob extraction step 412.

The license plate character recognition step 500 is characterized in that the characters divided in the individual character division step 400 are normalized to recognize individual numbers and Korean characters, and the individual character blob normalization step 510, individual numbers, and Korean characters recognition step It includes 511.

The step (600) of assembling the image data of the photographed license plate area includes a license plate region division and labeling step (610) of performing border-based division and labeling on the photographed vehicle license plate image, and the license plate region division and labeling step ( Including a license plate area scanning step 611 of selectively scanning a portion determined to be a license plate area at 610, and a step 612 of collecting license plate image data using the image scanned in the license plate area scanning step 611. Done.

Therefore, the vehicle license plate recognition camera system (C) according to the present invention selects and photographs infrared rays to secure clear image quality by blocking rays that interfere with obtaining clear images from the camera 20, The light of the headlight can be attenuated, and when the angle of entry of the target vehicle to be photographed is unique, or the position of the license plate is not constant, it is possible to shoot the license plate of a vehicle that cannot be photographed or photographed in advance. You can do it.

As described above, the above-described contents are merely illustrative of the technical idea of the present invention, and those of ordinary skill in the technical field to which the present invention pertains, within the range not departing from the essential characteristics of the present invention. Modifications, changes and substitutions will be possible.

Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings. . The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

5: optical lens 10: filter switching unit
11: cut-off filter 20: camera 30: image sensor 40: image processing means
41: image processing unit
42: image collection unit 42a: location recognition unit
43: image output port 45: power module 46: built-in battery 47: sensing unit 48: power control unit 61: management server 80: image output control module 90: communication unit
95: infrared emitter
V: number recognition server
L: Lens part S: Illumination sensor
C: License plate recognition camera system

Claims (4)

In the vehicle license plate recognition camera system,
One or more cameras formed with an optical lens and a lens unit (L) having a built-in filter switching unit consisting of a blocking filter and a polarizing filter for blocking infrared or visible light passing through the optical lens to photograph and transmit a license plate;
An image sensor for sensing an image image captured from the lens unit L;
An image processing unit that receives the converted digital signal from the image sensor and processes an image and an image collection unit that compresses the image by receiving the processed image signal and stores the compressed image are built-in, and the image information is transferred to an external image display device. An image processing means having an image output port for outputting;
A control server for controlling the camera and a storage server for storing an image, a display unit for displaying the image, a management server in which the control server, the storage server and the display unit are built-in by being connected to the camera through a wired/wireless network;
And a control unit connected with an infrared emitter for controlling the image processing means and allowing the camera to transmit infrared rays by blocking visible light when photographing at night.
The method of claim 1,
The filter switching unit transmits visible light during the day and blocks infrared and reflected light to generate a color image, and blocks visible light at night to transmit infrared to generate a black and white image. .
The method of claim 1,
The image collection unit may include a location recognition unit for recognizing the position of the license plate in the stored vehicle image;
And a number recognition server configured to recognize a character on the license plate from the image of the vehicle license plate recognized by the location recognition unit and measure the size of the recognized character.
The method of claim 1,
And an illuminance sensor that measures and detects illuminance in the predetermined area and transmits it to the image processing means.

Images