"Sunlight is the purest light and provides the purest color from the spectrum standpoint of the perception of color," explains Debbie Zimmer, paint and color expert with the Rohm and Haas Paint Quality Institute. But sunlight changes over time. As the day progresses and the earth rotates, the intensity of the light changes and you'll observe changes in the appearance of color.
In residential and commercial spaces, artificial lighting is frequently used to either supplement daylight or replace it entirely. The type of artificial lighting used plays a large role in how a color looks.
When you remove light — or tone it down — there is a different effect on the perception of color.
In the real world, there isn't just one kind of light at play — you typically have a combination. If there are large windows, it likely will be a combination of a lot of daylight, some artificial light and some shadows. With small windows, you may have the effects of only a little daylight, primarily artificial light and some shadows. But there's more to consider! You may have a southern exposure, with more direct daylight effects; a northern exposure, with mostly indirect daylight; an eastern exposure, with a lot of morning sun; or a western exposure, with mostly afternoon sun. Northern and western exposures provide cooler, bluish tones. Southern and eastern exposures are warmer, more yellow.
Putting it all together is where it can get complicated, Saylor says. There really is a lot at play. "A color may be modified by the quality of the light source (red light of a sunset); modified by light reflected from colored surfaces (light flooding a room reflected off of green trees and a lawn); modified by shadows in the surface texture (heavily textured white wall grayed by the shadows cast by the texture profile); and further modified by comparison with other colors in the same view (a red object being 'set off' or intensified by a green background)."