WHITE BALANCE

BOX 56-6 Summary

• Adjusting the white balance on the camera prior to taking photographs can compensate for unnatural looking color in photographs due to varying ambient light sources.

All light has color. Most of us do not think of it that way as our brains tend to color-correct light for us with no effort at all. Different sources of light produce different wavelengths which we identify using degrees Kelvin. This is commonly referred to as the light's “color temperature.” With digital cameras, this correction for different temperatures of light is called “white balance.” Daylight is the standard by which we measure color. Daylight being what we call white light causes colors to be reflected without a color prejudice. Yellow is seen as yellow, green as green, etc. When we use an artificial light source such as the fluorescent tubes in an office, the color of the light that is emitted produces an unnatural, usually somewhat greenish color when human skin is viewed under it. The camera records this unnatural color very well. For this reason, we must make an adjustment to the “white balance” setting of the camera if we choose to photograph subjects under fluorescent light. The same holds true for tungsten light found in common filament light bulbs, and for the tungsten/halogen hybrid bulbs found in many surgical situations. Fortunately, electronic flash is of a color temperature that is designed to be very close to that of daylight so a flash photo is generally close to being accurate when one uses a daylight white balance setting.

There are usually “presets” in the menu of most digital cameras that change the color sensitivity of the camera for various lighting situations. These may be adequate for some situations. For the most accurate recording of color, it is advisable to use a “custom white balance” procedure that is an option on most good digital cameras and is explained in the manual. If this custom white balance procedure is done properly once, you need not repeat it each time you use the same room and light source. Under no circumstances should one rely on a common setting found on most cameras called “auto white balance” or AWB. Few things in digital cameras work as poorly as AWB in office situations where color reproduction is critical.

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