The human eye can easily adapt to different light conditions so that objects maintain their ‘true’ colour.
In fact, each type of light amplifies a certain colour in the spectrum. What we consider to be ‘white’ light only occurs during the noon hours of a clear day. Sunlight in the early evening or late afternoon gives everything a reddish tint, and cloudy days bring out the blue end of the spectrum.
Each type of artificial light also has a particular colour cast. Incandescent lighting is yellowish and fluorescent lighting can be either blue or green.
All of these different lighting conditions affect the colour balance in photographs.
Most digital cameras allow you to adjust the colour balance for different types of light. This can be done manually or automatically, although the automatic settings can produce uneven results from one picture to another.
Manual settings can be done by selecting a preset such as ‘sunlight’ or ‘cloudy’, but these settings can be fine-tuned to match very specific lighting conditions.
Colour balance is achieved by adjusting the camera so that ‘white’ is truly ‘white’. Once the camera is set to correctly reproduce white, the other colours should appear to be their natural shade. This can be quickly checked by looking through the viewfinder of your digital camera. Holding up a piece of white paper in front of the camera will allow you to see whether it is the correct shade or not.
Some cameras can be set this way — place a sheet of white paper in front of the viewfinder and select ‘Auto Correct’.
Remember that the presets are general guidelines and may not be suitable for every type of lighting condition. If your camera has a setting for florescent lights, for example, it may still require further tweaking to get the correct colour balance.
Although it is best to try to get the proper colour balance when you are taking photographs, the colour of an image can also be adjusted using software. This should not be thought of as an alternative to proper colour balancing, but it can be used to good effect on some digital images.
Some computer software can automatically adjust colour as well as brightness and contrast. Start out with these ‘auto’ settings — sometimes the results can be surprisingly good.
This knowledge of how colours interact allows you to correct improper colour balances. For example, if an image is too red, adding some cyan (the opposite of red) can help to naturalize the colour.
Software can also be used to adjust colour intensity. Subtle use of imaging software can help to turn good photographs into great photographs.