Although we perceive most types of illumination as white, the colour of light can vary significantly. That's why images made under different types of illumination with Auto White Balance may exhibit an unusual colour cast: blue, amber or green, for example. You can minimize problems such problems using other White Balance (WB) options that your camera provides. And as a bonus, you can also use them as filters for creative effects.

Photo Caption: Your camera's White Balance options allow for making images with accurate overall colour balance or with specific effects, such as the "cool" (bluish) caste in this image to emphasize the cold, wintry conditions. (Lake Louise, Alberta; Daylight WB and WB Fine-Tuning) (c) 2008 Peter K. Burian

Outdoors, the light is white only during the hours around noon on a sunny day. In overcast conditions or in a heavily shaded area, the light is quite blue, while at sunrise and sunset it's yellow or red in tone. Indoors, the colour of artificial light varies too. It's green with older fluorescent tubes and orange with incandescent lamps. Sodium vapour and various esoteric types of lighting have even stranger colours. In any of these conditions, your images may have an unsatisfactory colour cast.

• WB indoors: Under artificial lighting when not using flash, set the camera's most suitable WB preset, such as Fluorescent or Tungsten/Incandescent. If that does not quite provide the intended effect, try the White Balance Fine-Tuning feature, if available with your camera. That allows you to shift the WB toward blue or yellow or magenta or green. If there's no way to get accurate results under artificial lighting, you'll need to use the Custom or Manual WB to teach the camera to render white as white under any type of lighting. Basically, that involves taking a test picture of a white or grey card, then letting the camera calibrate white balance. When whites are accurate, other colours should look fine as well.
• WB outdoors: The presets can be useful for accurate white balance, especially on heavily overcast days but they can also provide desired effects. For a warm glow; try the Flash, Cloudy or Shade WB presets. To emphasize the cool (bluish) light of a winter day, try the Incandescent/Tungsten WB preset.

Most current digital cameras allow you to preview the effect you'll get with any of the White Balance options, using Live View on the LCD monitor. Try several different settings until you find the one that's best, and perhaps tweak it a bit with WB Fine-Tuning. When the preview image looks just right, take the photo and you should need to do very little in computer software for the perfect overall colour balance.

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