The Effect of Light on Color

Color perception is directly dependent on the light source. In practice, a color can be metrically identical but be experienced visually completely differently. This article describes how this can happen and why knowledge of light is crucial for designers, architects, and color specialists.

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Practical Example: Facade Panels With No Measurable Difference

A manufacturer reported that two identical facade panels, placed at a 90-degree angle, showed visually different colors:

• One panel → yellowish white
• The other panel → bluish white

Instrumental measurement showed virtually no color difference. Yet it was visually clearly present. The cause: the light incidence.

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Why Light Affects Perception

Light determines how color appears. The spectral composition of light changes continuously and influences the color impression of a surface.

Daylight Varies by Moment and Location

• Morning → warmer, yellowish
• Noon → cooler, bluish
• Evening → warmer, orange

In addition, location and season play a role:

• Winter light → cooler than summer light
• Light in Australia → differs from light in the Netherlands

A white object therefore optically changes color throughout the day.

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The Need for Standardization

To achieve reliable color assessment, the CIE (Commission Internationale de l'Éclairage) has established standard light sources.

Important examples:

• D65 → standardized daylight, 6500 K
• A → warm artificial light, approx. 3000 K

Ideally, color assessment takes place in:

• A light booth
• A standardized assessment room

This minimizes the influence of variable light and makes visual comparisons repeatable.

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Back to the Facade Panels

Although the color difference was not instrumentally present, it arose visually due to the effect of sunlight on both surfaces:

• Different angles of incidence
• Different reflected spectrum
• Optical contrast through interaction with the environment

This can lead to:

• Visually disturbing differences, even with correct production
• Unconscious influence, whereby the eye perceives contrast that is not instrumentally measurable

In this case, the coating was delivered according to specification. The optical difference was solely attributable to the natural light conditions.

Minimizing this type of difference requires specialist knowledge of:

• Light geometry
• Material reflection
• Color assessment
• Metamerism and observation conditions

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Want to Delve Deeper into Color Measurement, Light, and Visual Assessment?

Knowledge of light, color perception, and assessment conditions is essential for anyone working with color-professional decisions.

👉 Learn this in the courses of the Dutch Color School: https://kleurenschool.nl

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Questions about light sources, color measurement, or visual assessment? Contact the specialists at the Netherlands Color Institute: https://kleurinstituut.nl/contact