What is white balance?
White balance, as its name implies, is white balance. Because of the adaptability of human eyes, white can be accurately judged at different color temperatures, but the camera is far from it. Under different color temperature light sources, the image will be biased, which is inconsistent with the color seen by human eyes, so white balance processing is needed. In digital cameras, there are often ISPs, in which AWB (automatic white balance) processing is done.
Simply speaking, white balance is defined as a function of "white" regardless of the ambient light. Because the CCD sensor itself does not have this function, it is necessary to modify its output signal, which is called white balance.
Color is essentially an explanation of light. Things that look white in normal light may not look white in darker light, and "white" in fluorescent lamps is also "non-white". If we can adjust the white balance, we can correctly restore other colors with "white" as the base color in the obtained photos. So the white balance control is to adjust the image so that the color of the photographs taken under various light conditions is exactly the same as the color of the scenery seen by the human eye.
There are three CCD electronic coupling elements in the industrial camera. They feel blue, green and red light respectively. Under the preset conditions, the electronic amplification ratio of the three sensing circuits is the same. The relationship is 1:1:1. The adjustment of white balance changes the proportion relationship according to the adjusted scenery.
For example, the proportion of blue, green and red light of the adjusted scenery is 2:1:1 (the proportion of blue light is more, the color temperature is higher), then the proportion of the adjusted white balance is 1:2:2. The proportion of obvious blue in the adjusted circuit enlargement ratio decreases, and the proportion of green and red is increased. Thus, the adjusted scenery is adjusted by the white balance circuit to 1:2:2. The ratio of blue, green and red will be the same. That is to say, if the adjusted white is slightly bluer, then the white balance adjustment will change the normal proportional relationship and weaken the amplification of the blue circuit, while increasing the ratio of green to red, so that the image is still white.
The parameter of camera white balance can be used to adjust the color of red and blue in the image to get realistic color. These values can be controlled manually or automatically. The automatic white balance function provides two modes of operation:
Automation: Continuous implementation of white balance operation on video data streams.
Single touch: trigger only one adjustment process.
Ordinary multimedia cameras only provide a white balance parameter, so increasing the red color value will reduce the blue color value, and vice versa. High quality cameras provide two parameters, so they can adjust the color values of red and blue respectively.