JP4587770B2 - Vehicle photographing method and apparatus - Google Patents

Description

  The present invention relates to a vehicle photographing method and apparatus for photographing a speed violation vehicle, an unauthorized traffic vehicle not paying a high-speed toll, etc. installed on a general road or a highway.

  Conventionally, as a method of specifying the above-described unauthorized traffic vehicle, a license plate of the vehicle is photographed with a camera, and the unauthorized traffic vehicle is specified from a photograph of the license plate. As a method for photographing such a license plate, for example, there is an invention disclosed in JP-A-2002-300437.

According to the present invention, a license plate of a vehicle is photographed by a camera, and the photographed image is processed by setting the value of γ to 1.0 during daytime and the value of γ to 0.45 at night. Even when the illuminance is low, such as at night, image processing can be performed more appropriately without using a lighting device with a large amount of light.
JP2002-300437

By the way, in order to identify the above-mentioned violation vehicle as the needs of road managers, there is a request to obtain not only a license plate but also a facial photograph of the driver who committed the violation, but a driver's seat with a low brightness value throughout the day and night In order to photograph clearly, even if the invention for recognizing the license plate described above is applied, in order to photograph the driver and the license plate at the driver seats having different brightness values at the same time, the brightness value of the license plate is There was a problem that the entire vehicle was brightly lit so as not to go up too much, or dedicated lighting for the driver's seat was required.
However, in the former method of brightening the entire vehicle, the luminance value of the license plate itself also increases, so that there is a problem that it cannot be read.

  The present invention is intended to solve the above-described problems, and an object of the present invention is to provide a vehicle photographing method capable of obtaining a photographed image in which both a license plate number and a driver's face photograph are clarified, and I will provide the device.

The vehicle photographing method of the present invention achieves the above-mentioned object, and the means of claim 1 shoots an original image including a license plate of a passing vehicle and a driver's face when a vehicle detection signal is inputted. Is stored in the license plate portion of the γ corrected image obtained by performing γ correction with the γ value corresponding to the illuminance of the portion through which the vehicle passes with respect to the stored original image. The license plate is extracted from the original image by the license plate extraction means and the stored license plate image is synthesized by pixel replacement to clarify the driver's face and the license plate number. .

According to a second aspect of the present invention, in the first aspect, the license plate is extracted based on a license plate size stored in accordance with a vehicle type in an area defined in advance by a vehicle type signal obtained by the vehicle type determination unit. It is characterized by performing matching and extraction using a corresponding template .

According to a third aspect of the present invention, there is provided a photographing means for photographing an original image including a license plate of a passing vehicle and a driver's face when a signal indicating that the vehicle has detected passage is input. An original image memory for storing the original image taken by the photographing means, and γ correction by γ value according to the illuminance of the portion through which the vehicle passes with respect to the original image stored in the original image memory Γ-corrected image generating means for obtaining a corrected image; license plate extracting means for extracting and storing a license plate portion from the original image stored in the original image memory; and the license plate portion obtained by the γ-corrected image. It comprises image synthesizing means for synthesizing the image stored in the plate extracting means by pixel replacement.

According to a fourth aspect of the present invention, in the above-described third aspect, the license plate extracting unit has a license plate size stored in accordance with a vehicle type in an area defined in advance by a vehicle type signal obtained by the vehicle type determining unit. It is characterized by performing matching using a corresponding template and extracting .

  As described above, according to the present invention, an image obtained by extracting a license plate from a photographed original image is stored in advance, an image obtained by γ-correcting the original image with a predetermined γ value is obtained, and the γ-corrected image and the stored image are stored. By synthesizing the original image of the license plate, the number of the license plate and the driver's face in the driver's seat become clear in the synthesized image.

  In addition, by changing the γ value according to the ambient brightness, and obtaining a γ-corrected image with the changed γ value, a clear image can be obtained regardless of the surrounding brightness. It has effects such as.

  The present invention obtains an image in which the brightness value is increased by performing gamma correction on the driver seat having a low brightness value over the day and night, and by combining the license plate original image with the previously stored license plate original image, A photograph of the driver of the seat is generated as a clear image.

Hereinafter, an embodiment of a vehicle photographing apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a system block diagram, and 1 is composed of a digital camera or the like that is installed at a toll booth or the like and that converts a video signal captured by an imaging unit (not shown) to capture an illegal traffic vehicle into a digital signal format and outputs it. Yes.
The photographing means 1 performs photographing by inputting a vehicle detection signal from a vehicle detector (not shown).

Reference numeral 2 denotes a control means for performing luminance conversion on the photographed original image, and is constituted by each memory and means described below.
2a is an original image memory for storing a digital image from the photographing means 1, 2b is a known vehicle type discriminating means for discriminating a vehicle type such as a large car, a normal car, a light car, etc. according to the height of the vehicle, etc. The extracted image is temporarily stored in a memory by using a license plate extraction means for extracting a license plate using a template matching method or the like according to a license plate area defined by the vehicle type obtained by the vehicle type discrimination means 2b. The

  2d is an illuminance detecting means for detecting the illuminance of a portion that is installed around the photographing means 1 and through which the vehicle passes; 2e is stored with γ values of 2.5 and 1.5; and the illuminance detecting means When the output of 2d is high when the preset illuminance is high, for example, when it is daytime, a γ value of 2.5 is output, and the illuminance is low, for example, at night When the output is sent, a γ value table 2f that outputs a γ value of 1.5 is a γ value selected from the γ value table 2e with respect to the original image stored in the original image memory 2a. It is a γ-corrected image generating means for correcting and obtaining a γ-corrected image.

  Also, 2g is an image synthesizing means for replacing the license plate image extracted by the license plate extracting means 2c with the license plate position of the γ corrected image generated by the γ corrected image generating means 2f, and 2h is a liquid crystal monitor. An output unit 2i for displaying an image on the display means 3 comprising, for example, an operation signal from an operation means 4 having an operation switch (not shown) for controlling the photographing means 1 and switching the image on the display means 3 An input unit 2j for inputting is a program memory storing a control program for executing the vehicle photographing method of the present invention, and 2k is a CPU for controlling each of the above-mentioned memories and means according to the control program.

  Next, the processing operation of the present invention will be described with reference to the flowchart of FIG. In this embodiment, a description will be given on the case of taking a license plate of a fraudulent vehicle passing through a toll booth and a photograph of the driver's face, but the processing operation is the same for highways and ordinary roads.

  First, to explain the flowchart of FIG. 2A, the illuminance detection means 2d detects the illuminance of the portion of the toll gate through which the vehicle passes (step S1). Then, for example, in the case of daytime illuminance corresponding to the illuminance at this time, the γ value 2.5 indicated by the two-dot chain line in FIG. 3 is selected as the correction value in the γ value table 2e. In the case of illuminance, a correction value of γ value 1.5 indicated by a dotted line in FIG. 3 is selected in the γ value table 2e (step S2). The γ value with respect to illuminance is not limited to the two values of daytime and nighttime, and a value between 1.5 and 2.5 can be linearly selected in the γ value table 2e according to the illuminance. It is also possible.

  Next, the entire processing operation will be described with reference to the flowchart of FIG. 2B. First, it is determined whether or not there is a vehicle detection signal in which an illegally passing vehicle passing through the toll gate is detected by a known vehicle detector (step S11). ), The front of the vehicle is photographed by the photographing means 1 based on the determination that the vehicle detection signal is present (step S12). Next, the captured digital image of the vehicle is stored in the original image memory 2a (step S13).

  Here, since the original image stored in the original image memory 2a is the image of FIG. 4 at daytime, the number on the license plate looks clear, but the driver's face is difficult to see, and at night Then, since the image shown in FIG. 7 is obtained, the number on the license plate can be clearly seen as in the daytime image, but the driver's face is difficult to see.

  Next, corresponding to the size of the license plate stored in accordance with the vehicle type for the area defined in advance by the vehicle type signal obtained by the vehicle type discrimination means 2b for the digital image stored in the original image memory 2a. Matching is performed using the template to be cut out and the license plate is cut out (step S14). Then, the CPU 2j stores the license plate image and position extracted by the license plate extraction means 2c in the memory of the CPU 2j (step S15).

  Next, during daytime, the γ correction image generation means 2f performs γ correction with the correction value of γ value 2.5 set in the γ value table 2e, thereby obtaining the γ correction image shown in FIG. 5 (step S16). ). Looking at the γ-corrected image in FIG. 5, the driver's face is clear, but the license plate is too bright as in the case of the vehicle, so the number on the license plate is difficult to see.

  On the other hand, during nighttime, the γ correction image generating means 2f performs γ correction with the correction value of γ value 1.5 set in the γ value table 2e to obtain a γ correction image (step S6). This γ-corrected image is in a state where the driver's face can be clearly seen as in the daytime.

  The image in FIG. 9 shows a case where the γ value is 2.5 and the γ correction is performed by the γ correction image generating means 2f. It turns out that it is very profitable and it is necessary to lower the γ value at night.

  Next, the license plate image extracted by the license plate extraction unit 2c and stored in the license plate portion of the γ correction image obtained by the γ correction image generation unit 2f is synthesized by pixel replacement by the image synthesis unit 2g ( Step S17), the composite image at daytime is shown in FIG. 6 and the composite image at night is shown in FIG. 8 where the driver's face and number on the license plate are clear, and the violation vehicle and the driver can be identified. It can be done clearly.

  In the above-described embodiment, the case where the photographing unit 1 is operated when the vehicle detector detects the vehicle as the timing for photographing the original image has been described. However, the vehicle is directly selected from the images periodically photographed by the photographing unit. You may make it detect and cut out a license plate.

1 is a system block diagram of a vehicle photographing apparatus according to the present invention. It is a flowchart for demonstrating the operation | movement same as the above. It is a characteristic view which shows a gamma correction curve. It is an original image photograph at daytime. It is the photograph after carrying out (gamma) correction of the image same as the above by (gamma) value 2.5. It is the photograph which synthesize | combined the gamma correction image and the license plate of the original image. It is an original image photograph at night. It is the photograph after carrying out (gamma) correction of the image same as the above by (gamma) value 1.5. FIG. 8 is a photograph when the original image of FIG. 7 is γ-corrected with a γ value of 2.5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image | photographing means 2 Control means 2a Original image memory 2b Vehicle type discrimination | determination means 2c License plate extraction means 2d Illuminance detection means 2e γ value table 2f γ correction image generation means 2g Image composition means

Claims (4)

When a vehicle detection signal is input, an original image including the license plate of the passing vehicle and the driver's face is photographed and stored by the photographing means, and the stored original image according to the illuminance of the portion through which the vehicle passes In the license plate portion of the γ correction image obtained by performing γ correction with the γ value, the number plate portion is extracted from the stored original image by the license plate extraction means, and the stored license plate image is a pixel. A vehicle photographing method characterized in that the driver's face and the number on the license plate are clarified by synthesizing by replacement.   The extraction of the license plate is performed by performing matching using a template corresponding to the license plate size stored in accordance with the vehicle type with respect to the area defined in advance by the vehicle type signal obtained by the vehicle type discrimination means. The vehicle photographing method according to claim 1, wherein: An imaging means for capturing an original image including a license plate of a passing vehicle and a driver's face when a signal indicating that the vehicle detector detects the passing of the vehicle is input;
An original image memory for storing an original image photographed by the photographing means;
Γ-corrected image generating means for obtaining a γ-corrected image by performing γ-correction on the original image stored in the original image memory with a γ value corresponding to the illuminance of the portion through which the vehicle passes;
License plate extraction means for extracting and storing a license plate portion from the original image stored in the original image memory ;
Image synthesizing means for synthesizing the image stored in the license plate extracting means by pixel replacement with the license plate portion obtained by the γ-corrected image ;
A vehicle photographing apparatus comprising:   The license plate extraction means performs matching using a template corresponding to the license plate size stored in accordance with the vehicle type for the area defined in advance by the vehicle type signal obtained by the vehicle type determination means, and performs extraction. The vehicle photographing apparatus according to claim 3, wherein:

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