White balance – WB

White balance is a function commonly used in video cameras and digital cameras. Human eye can identify the same colour in various objects under different lighting conditions, however, the video camera or digital camera cannot. Those devices record the colour depending on the hue of the incident light. White balance can be used to improve colour rendering in the recorded images.

In automatic mode, the device identifies the brightest point and uses it is a reference point for white. Based on that, it can determine the temperature of other colours in the image. Colour temperature is measured in degrees Kelvin. Colour temperature is determined by the type of light. It means that with the increase in colour temperature the light seems colder (5,500 to 10,000 K) and with the decrease in colour temperature the lights seems warmer (3,000 to 5,000 K).

Almost all CCTV cameras have an advanced AWB (Automatic White Balance) function to adjust the colours to the light at different temperature. AWB eliminates unrealistic colours. Its aim is to compensate for the prevailing colour to generate images as they appear to the human eye.

Another advanced functions is an ATW (Automatic Tracking White Balance), an extension of AWB. The function analyses all image areas for different white values. Unlike cameras with automatic white balance, ATW cameras have a built-in white balance reference for correct white rendering even for uniformly coloured scenes.