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2. The minimum illumination of the camera is also called sensitivity. The minimum illuminance index can not only look at the number of the front, but should see under what conditions this indicator is measured. For example, the minimum illumination of color is 0.15 Lux/F1.4/50 IRE/AGCON, which indicates that the low illumination of 0.15 Lux is achieved with a F1.4 pass lens, and the video signal measurement level is measured at 50 IRE (350 mv) under AGCON conditions. If the F1.0 lens with a large amount of light is replaced, the video signal measurement level is at 25 IRE, and the measured low illumination index is even lower. The 1/2-inch CCD camera has higher sensitivity and image quality than the 1/3-inch CCD camera.
With regard to the IRE, the maximum amplitude of the video output of the CCD camera is defined to be 100 IRE or 700 mV. A 100 IRE video representation can completely drive a monitor to display the best brightness and contrast. Only 50 IRE or 350 mV video represents only half Contrast, 30 IRE or 210 mV represents only 30% of the original amplitude, usually 30IRE is the lowest available image value, a standard camera should have a noise level of 10 IRE when the auto gain is increased to maximum gain, thus providing 3: 1 or 10dB SNR acceptable image. A result measured at 10 IRE can be 10 times higher than that measured at 100 IRE, so no results that indicate the IRE level are actually meaningless.
3, the camera's signal to noise ratio. When the light is very good, the camera's signal-to-noise ratio is very good, the noise point can not be seen in the image, but when the light is dark, the camera image with good signal-to-noise ratio is still clear, the noise point is less, and the noise is small. For cameras that are worse than the index, noise points will overwhelm the entire image.
4, strong light suppression. Road surveillance cameras require clear camera licenses at night, which requires better light suppression indicators. In professional broadcast television cameras, this indicator is called low vertical spot. The camera adopting this technology can effectively suppress the bright light on the front, make the license plate of the car more clearly captured, and the picture is true and complete. Many road surveillance cameras use "solar eclipse" technology, which is very good for shooting license plates at night, but it often occurs during the day, which affects the overall appearance and integrity of the image.
5, backlight compensation. The camera captures license plates at night. The quality of the backlight compensation technology is directly related to whether the license plate can be clearly seen and whether the rear-end video detection and analysis system can give correct judgment results.
6, the camera's color reproduction. The camera does not have a specific color index, and only the color adjustment and white balance adjustment can be used to restore the true color. The degree of color reproduction is different for different types of cameras. This indicator is only compared through debugging and actual color in the scene.
7. The camera must be of reliable quality and easy to debug during installation. Road surveillance cameras are mostly installed on posts that are 9 to 15 meters high. They require special tool carts or dangerous overhead work for installation and removal. If the quality is not reliable or the commissioning is inconvenient, it will inevitably cause great costs for construction and engineering. Affect normal use.
License plate recognition camera function requirements!
1, the camera definition requirements. The horizontal resolution of the image is greater than 480 lines. High-definition cameras are equipped with high-definition monitors.