Picture This: Getting Colors Right
‘White balance’ settings compensate for variations in light.
By Earl Nottingham
The human eye is a remarkable tool. Unlike film or digital sensors, it not only can distinguish between billions of individual colors but also compensates so that colors appear realistic regardless of the conditions under which they are illuminated.
For instance, our eyes perceive a white shirt as “white” or a gray object as “gray” whether they are outside on a sunny day, under the shade of a tree or inside a room lit by various light sources. Alas, film and digital sensors do not have the ability to recognize the lighting conditions (and hence the color of the light source) under which the photograph is being made.
This is why we are often disappointed when photos taken without a flash inside a room lit by regular tungsten light bulbs take on a yellowish-orange cast and those taken under fluorescent bulbs appear a ghastly green.
With traditional film, options are limited regarding the ability to compensate for different light sources. Most films are “daylight” balanced, meaning that photos shot with direct sunlight or flash would yield pleasing colors. The alternative is “Type B” film, which is color-balanced to compensate for the warm color inherent in tungsten lighting. If you accidentally shot Type B film outside, your image would have a very strong blue cast. Numerous color-compensating filters are commonly used to make colors appear accurate under different light sources when using film.
Thankfully, digital cameras offer an easier solution to the issue of getting accurate color under almost any lighting condition, particularly when capturing images as JPG files (we’ll save RAW files for a later column). It’s called white balance, and every digital camera has several preset and customizable settings that allow the user to fine-tune white balance for a particular lighting situation, the equivalent of using color-compensating filters with traditional film.
The white balance choices are generally found in the menu or functions screen of the camera and consist of several presets represented by icons for common lighting conditions such as daylight, cloudy, shade, tungsten and fluorescent. You will also see auto and custom white balance settings.
Many users prefer to use the auto setting, allowing the camera to choose the color balance. Although not as accurate as the other presets or custom settings, the auto setting does an adequate job for snapshots where critical color isn’t needed.
Some higher-end cameras will have a K setting that allows you to set white balance based on Kelvin temperature, the numerical scale referencing the color of transmitted light.
By far the most accurate white balance is achieved by using the custom setting. This allows a white balance to be set from any light source and is especially useful when shooting in a room with a mixture of light sources such as fluorescent, tungsten and daylight. Generally, this is done by pointing the camera at a solid white reference like a tablecloth or piece of paper and then registering that object to the camera as white.
Each camera maker has a different method of performing a custom white balance, so consult your owner’s manual for the prescribed method.
For critical white balance, there is a handy product called the ExpoDisc (www.expoimaging.com), a calibrated filter that accurately measures the light directly from the source.
Please send questions and comments to Earl at firstname.lastname@example.org.