Backlight compensation, also known as backlight compensation, so what is backlight compensation? What is the concept of backlight compensation? The following is a detailed introduction. The backlight compensation is also called backlight compensation or backlight correction. It can effectively compensate for the darkness of the main body of the camera when shooting in a backlight environment.
Backlight compensation, also known as backlight compensation, divides the picture into several different areas, each of which is exposed separately. In some applications, the field of view may contain a very bright area, while the contained subject is surrounded by a bright field, the picture is dim and layerless. At this time, since the signal level detected by the AGC is not low, the gain of the amplifier is very low, and the brightness of the main body of the picture cannot be improved. When the backlight compensation is introduced, the camera detects only one sub-area of ​​the entire field of view. The average signal level of this region determines the operating point of the AGC circuit.
Backlight compensation provides the ideal exposure of the target in front of very strong background light, regardless of whether the primary target moves to the middle, up, down, left or right or anywhere on the screen.
When the camera is shooting in a backlight environment, a black image will appear on the screen. However, in the security, the backlight environment is difficult to avoid. At this time, backlight compensation is required. When the backlight compensation function is introduced, if the camera detects that the video level in a region of the captured image is relatively low, the video level of the region is improved and improved by the AGC circuit described above, and the amplitude of the output video signal is increased to make the image as a whole. Clear and bright. If the subject you want to see is dim due to the bright background, you can set the BLC to ON to compensate for the strong backlight.
What is backlight compensation? To put it simply, in a weaker environment, a darker background can also give a clearer picture.
Backlight compensation provides the ideal exposure of the target in front of very strong background light, regardless of whether the primary target moves to the middle, up, down, left or right or anywhere on the screen. That is, an object that can see the backlight, but the things behind the object are not clear.
An ordinary camera that does not have super dynamic characteristics has only a shutter speed of 1/60 second and an aperture of F2.0. However, a very bright background behind a main target or a point source is inevitable, and the camera will acquire It is not a good idea to average the incoming light and determine the level of exposure, because as the shutter speed increases, the aperture is closed and the main target becomes too dark to be seen. To overcome this problem, a method called backlight compensation is widely used on most cameras by weighted region theory. The image is first divided into 7 or 6 regions (the two regions are repeated), and each region can be independently weighted to calculate the exposure level. For example, the middle portion can be added to the remaining blocks 9 times, so one is in the middle of the picture. The target of the position can be seen very clearly, since the exposure is mainly calculated with reference to the light level of the middle area. However, there is a very big drawback. If the main target moves from the middle to the top, bottom, left and right positions of the picture, the target will become very dark, because now it is not distinguished and has not been weighted. The above is the concept of backlight compensation for the China Security Network Xiaobian. I hope everyone can learn more.
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