01 What Is White Balance

White Balance is a color‑balancing technique in photography. It adjusts color balance within an image to render white objects as human‑perceived white under varied light sources and shooting environments. It eliminates color casts and restores subjects’ true colors.

Put simply: it ensures white objects look white in photos.

a How Light Sources Affect Shooting

Why do white objects sometimes fail to appear white in captured images? The answer lies in light sources.

Different lighting conditions produce distinct color shifts in photos. Under certain illumination, captured colors can deviate drastically from real‑world appearance. For example, white paper shot under warm candlelight or incandescent lamps will take on a reddish tint. White‑balance adjustment corrects such distortion and recovers original colors.

b Color Temperature

To understand white balance, you first need to grasp color temperature, a concept used in photography, television and display devices.

Definition of color temperature in physics: When an ideal black‑body is heated from absolute zero, it emits light of varying colors at different temperatures. If light from a real‑world light source matches the light emitted by a black‑body heated to a specific Kelvin temperature value, that Kelvin value is defined as the light source’s color temperature.

In plain terms, color temperature describes how “warm” or “cool” a light source is. Note the counter‑intuitive rule: warm tones such as orange and red correspond to low color‑temperature values, while cool tones such as blue and white correspond to high color‑temperature values.

White‑balance adjustment essentially calibrates against color temperature. Telling the camera the color temperature of the shooting scene enables the camera to calibrate the image and restore subjects’ natural colors.

c Why Is It Called White Balance?

Photography and color theory are built on the RGB three‑primary‑color model: all visible colors can be reproduced by mixing red, green and blue.

Pure white carries RGB values of 255,255,255 (FFFFFF), with no bias toward any single color channel. If white is reproduced accurately, all other hues will render correctly. In practice, gray cards with equal RGB channel values can also serve as white‑balance calibration references, which will be explained below.

02 White Balance in Shooting

As covered above, white balance restores true subject colors by ensuring white renders white under different light sources. Below is how white balance is applied in shooting.

a Auto White Balance

Nearly all cameras feature Auto White Balance (AWB), where the camera detects ambient color temperature and uses it as the white‑balance parameter.

Advantage: Simple and hands‑off, requiring minimal manual setup.Disadvantage: Color casts may occur if scene recognition algorithms misinterpret lighting conditions.

b Manual White‑Balance Scenarios

White balance works by informing the camera of ambient color temperature for color calibration. Scene‑based white‑balance presets tell the camera what type of light is present; the camera applies built‑in corresponding color‑temperature mappings for correction.

Users may also input a specific numerical color‑temperature value directly, forcing the camera to calibrate using that fixed value to achieve similar results.

c Calibration Using Gray Cards / White Cards

Most users cannot accurately read real‑time color‑temperature values. Gray cards or white cards solve this problem.

Calibration principle: shoot a gray or white card on‑site to provide the camera with a neutral‑white reference benchmark. The camera uses this reference frame to set white‑balance parameters automatically.

A white card provides a pure‑white reference point. However, achieving proper exposure for a white card can be tricky, so an 18‑% gray card is widely used as an alternative reference. Both gray cards and white cards feature equal RGB channel values, qualifying them for white‑balance calibration.

Shoot the gray or white card within the scene; the camera takes the card’s captured color as the neutral benchmark and completes white‑balance calibration. Though purchasing reference cards is required, this delivers the most accurate white‑balance results.

d RAW‑File Post‑Processing Calibration

Camera images originate from sensor data. Standard JPEG files are generated after sensor data runs through algorithms, white‑balance correction and data compression.

When shooting in RAW format, raw sensor data is preserved. White balance can be re‑adjusted freely in post‑processing software such as Adobe Lightroom.

03 Summary

In short, white balance calibrates for varied color‑temperature lighting conditions. By getting white to render correctly, it recovers the true colors of photographed subjects.

Common white‑balance workflows include automatic camera adjustment, manual selection of light‑source presets or specific color‑temperature values, and calibration via white or gray reference cards. For cameras supporting RAW capture, white‑balance parameters can be modified afterwards during post‑production.