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Take a sheet of white paper outside in to the daylight and it will appear bright white. Take the same sheet of paper in to an indoor environment lit by artificial lighting, and it will still appear white although probably less bright. However, do not be deceived. Indoors, the paper no longer really appears white. The colour temperature of the artificial lighting is reflected from the white surface of the paper and what the human eye sees is a warm yellowish tint (in the case of tungsten lighting). The reality is that the brain knows the sheet of paper is white and makes a very subtle and sophisticated adjustment to the signals received from the eyes. Hence the paper is still seen as white. Digital cameras, and indeed film cameras, are not as clever as the human brain. They record faithfully the wavelengths of light they receive. It may therefore be necessary for the photographer to use a film designed for artificial light, or tell a digital camera to make an appropriate adjustment. This is where white balance becomes important.

The white balance control on digital cameras can be used to adjust shooting parameters to suit the prevailing colour temperature of the light. It is relatively easy to set an appropriate white balance for most normal scenes. Standard modes include sunny, shade, cloudy or hazy, flash, fluorescent, tungsten and auto. Each setting implies a degree of compromise, but errors of less than about 250K are unlikely to be noticed.

Typical settings found on digital cameras include:

Other sources may require different settings. Sodium vapour light, often found at sports venues, may require a colour temperature setting of 2,700K. High temperature mercury vapour light may measure as high as 7,200K.