The system is based on the principle of radiation imaging, and the fan-shaped rays emitted by the radiation source penetrate the seal 
Closed compartment and inside cargo, received by the other side detector. Because different substances have
Different density, so the absorption of the ray is different, the ray penetrates the object to be tested
On the detector, the strength of the detector output signal is different; The signals will vary in strength
The signal amplifier is amplified, the analog signal is converted into a digital signal, and then passed
The image capture card transforms the digital signal into a two-dimensional or three-dimensional image on the computer screen
It is shown that the inspection of the goods inside the inspected vehicle can be completed by looking at the line of sight
Work.

The use of radiation to penetrate the closed compartment, image the internal goods, inspectors by looking at the image of the computer monitor, understand the loading of goods in the compartment, and then determine whether there is a suspicious vehicle.




Scan check process
Be in order
The image inspector operates the software and enters the "inspection mode"; Check the gantry system. The blue ready indicator and the yellow working indicator are blinking. If the computer shows that the system is faulty (security interlock), check the system status, clear the fault, and then detect.
Equipping Items
After the image checker, system guide and image rechecker are in place, lift the rod to guide the vehicle.
Scan
Inform the driver of slow speed (big car: uniform speed 3~5 km/h; Car: After driving at a constant speed of 1~3 km/h through the equipment, stop at the green detection kiosk, when the vehicle passes, if an emergency is found, you can press the emergency stop button to stop the system.
Note: The layout of testing equipment and kiosks varies according to the layout of different systems. The above situation is for the equipment before the detection booth.
Inspect
After the vehicle passes through the detection equipment, the vehicle scan image is automatically displayed on the computer screen of the Green inspection kiosk. If the check software does not automatically pop up, select the top file in the left browser bar of the main program, which is the most recently checked image. If there is no record of the vehicle in the most recent inspection image, the scan should be resumed after troubleshooting the equipment.
conclusion
According to the results of the scan image judgment, if abnormal, notify the guide to review, if normal, the vehicle will be released. In the remarks to the right of the master control program, enter the name of the items the vehicle is carrying for later analysis.



The foundation of image recognition
Usually, people use the absorption and reflection of visible light by objects to see colors and object contours, and then make judgments and recognition.
The imaging method of ray penetration is completely different, as the images of various objects it forms are inconsistent with our inherent impressions in the brain. Therefore, it is necessary to establish a corresponding relationship between the actual objects and the images based on understanding the imaging principle, in order to adapt to new visual sensations.
The significance of image grayscale
Grayscale can also be considered as brightness, simply put, it refers to the depth of colors or the brightness of the image. Grayscale refers to the color depth of points in black and white images. If the range is from 0 to 255, black is 0, so black and white images are also known as grayscale images and have a wide range of applications in the fields of medicine and image recognition.
The difference in density and thickness is the basis for generating image contrast. Due to differences in density and thickness, different objects have varying levels of radiation shielding intensity.
Objects with low density or thickness display larger grayscale values on the image, while colors are lighter on the image;
Objects with high density or thickness display small grayscale values on the image, while the color on the image is dark. (Essential grasp)
Because different objects have different differences, different areas of the same object also have differences in density and thickness, so the differences and contours of different objects can be seen in the image.
As shown in the figure below, objects of different shapes have varying thicknesses, resulting in different grayscale values in the image.



At the same time, the edge of the object presents grayscale discontinuity. Through edge detection, that is, the place where the grayscale level or structure has a mutation, it indicates the end of one area and the beginning of another area. This discontinuity is called the edge.
The grayscale of different images is different, and there is an obvious edge at the boundary, which can be used to segment the image. Naturally, this feature can be used to distinguish the goods in the carriage.
The differentiation methods are:
First, at the same latitude, the density/brightness of the same item is consistent. (Overall grasp, horizontal view, from left to right)
Second, adjust the grayscale value, the grayscale/brightness of the same item is gradual. (Overall grasp, vertical look at the picture, top down)