Chapter 29Part 4: Color Theory
A white wall can look amber under a lamp and blue in open shade. Learn what your camera is correcting, then decide which color of light you want the photograph to keep.
White balance is a color correction that makes a neutral object look neutral under the light in a scene. It counters the light's color cast so white looks white and gray looks gray. The adjustment shifts the other colors in the photograph too.
A camera records the light reflected by a subject. Under an orange lamp, a white shirt reflects that orange light and may look yellow in the photo. Under blue shade, it may look blue. Our eyes and brain adapt quickly; the camera needs a white balance choice to decide what should count as neutral. That choice can aim for accurate color or deliberately preserve the character of the light.
Kelvin (K) describes the warm-to-cool character of many light sources. A household tungsten lamp is often around 2,700–3,200 K, midday daylight near 5,200–5,600 K, and open shade can look much bluer. These are starting ranges; real lights and weather vary.
A camera setting near the light's temperature aims to make a neutral surface gray or white. Set the camera to a higher Kelvin number and the rendered photo gets warmer; set a lower number and it gets cooler. The camera is compensating for the light, which is why the direction feels backward at first.
Two lights can have similar Kelvin values yet differ in green or magenta. Some fluorescent and LED sources show this clearly. Use tint after temperature: move toward magenta to counter green, or toward green to counter magenta.
Neutral is a reference, not a rule. A gray card can help you find an accurate starting point. A sunset may look better with its warmth intact; blue twilight may deserve to stay blue. Decide whether accuracy or atmosphere serves the photograph.
White balance changes color, not the amount of light recorded. A photograph can have a good exposure and still have an unwanted color cast.
Choose the light falling on this illustrated room. Adjust the camera setting and watch the two neutral cards. In Mixed light, the lamp and window have different colors, so a single global white balance cannot make both cards neutral at once.
Like using a gray card, choose which light you want to neutralize.
This is an illustration of channel correction, not a calibrated camera preview. Actual results depend on the light spectrum, sensor, camera profile, exposure, and display.
AWB estimates the scene and works well when you move between different lights. Check the preview when a frame is dominated by one color, such as a red wall or sunset. AWB may try to remove a color you meant to keep and may vary from frame to frame.
Daylight, Cloudy, Shade, and Tungsten are quick starting points. A fixed Kelvin setting keeps a series consistent under steady light. Remember that a Shade preset is usually a warmer correction than Daylight because shade itself tends to be blue.
Place a neutral gray card in the same light as the subject and use your camera's custom white balance procedure, or photograph the card for a RAW editor's eyedropper. A colored wall or a white page with optical brighteners can mislead the reading.
These approximate temperatures describe the light source. Matching the camera's Kelvin setting is a neutral starting point; adjust by eye or with a gray card. Preset names and their exact values vary by camera.
| Light on the subject | Typical range | Try in camera |
|---|---|---|
| Household tungsten lamp | 2,700–3,200 K | Tungsten or about 3,000 K |
| Midday sun or flash | 5,200–6,000 K | Daylight, Flash, or about 5,500 K |
| Cloudy daylight | About 6,000–7,000 K | Cloudy or a warmer Kelvin setting |
| Open shade | About 6,500–8,000 K | Shade or a higher Kelvin setting |
| Fluorescent or LED | Varies widely | Try the matching preset, then adjust Kelvin and tint |
For example, a 3,000 K lamp photographed at a 5,500 K camera setting looks warm. Set the camera near 3,000 K to neutralize it. Under blue shade, moving the camera setting higher adds warmth. If you leave the camera at Tungsten while lighting a subject with daylight-colored flash, that subject can look blue. The same numeric Kelvin and tint settings can still render differently on different camera models and in different RAW software.
RAW and JPEG: A RAW file keeps sensor data and lets you change the white balance interpretation later with much more latitude. A JPEG has the chosen balance baked into its rendered pixels; large corrections can degrade color and reveal clipping. Even with RAW, a sensible in-camera setting gives a useful preview and a consistent starting point.
A warm lamp and a blue window can light different parts of a room. One global setting shifts both, so making the lamp-lit card neutral leaves the window-lit card blue. In the lab, switch to Mixed light and sample each card in turn.
Kelvin describes the blue–amber axis, but it does not fully describe every LED or fluorescent spectrum. A tint adjustment may help a global cast, but it will also shift areas that were already correct. Green light bouncing from a nearby wall onto only one side of a face needs a local correction or a change in the scene. Missing wavelengths cannot always be recovered perfectly.
Find a neutral object near a subject under one steady light. Keep the framing and exposure the same for all three photographs.
Compare: What happened to the neutral object, skin or familiar colors, and the feeling of the scene? If you shot RAW, try the same three interpretations in the editor. Repeat near a window and lamp to see why mixed light is harder.
Further reading: Visual Education: White Balance in Photography and Photography Life: Understanding White Balance. This lesson and illustration are original.