Physical factors can interfere with our ability to see and describe colors the same way others do. That subjectivity gets in the way when we try to execute a designer’s vision or specify a change. It can also interfere with our ability to visually match a color to standard for production purposes.
As noted in our recent blog on the science of color perception, these physical factors might include:
- Light source
The most important of these, since it’s fundamental to the way we see colors, is light.
The most critical factor: Light
Color of light
Objects absorb and reflect light. We can only see objects that reflect light into our eyes, and the color we see depends upon the wavelengths of light that are reflected. When the visible spectrum is reflected equally, we perceive an object as white. When it absorbs most light, we see it as black.
Color in light, unlike pigment, depends on the spectral energies contained in the light. Objects that appear red reflect the red energy while absorbing all others. Without the red energy a normally “red” object will appear black.
Light we perceive as “cool” includes more blue than does “warm” or yellowish light. The color of a light source can be described by measuring the relative powers of various wavelengths. As this spectral power distribution (SPD) changes, so does the way light is reflected to our eyes, which affects the colors we perceive.
Light sources are measured according to their ability to accurately reveal colors in comparison with natural lighting. This value, determined by the spectrum of the light source, is called a color rendering index (CRI) and is often indicated on commercial lamps. The CRI for natural, outdoor light is 100.
Retailers, restaurateurs, and office space designers are among those who routinely consider CRI in an effort to make goods more attractive and an atmosphere more inviting. But natural light varies with the weather, time of year, time of day, and position of a building, among other factors.
Lighting designers can make adjustments by careful selection of artificial light. And paint and textile colors can be chosen to offset characteristics of natural light. For instance, indirect northern light can make colors appear darker, so a designer might select brighter paint and textile colors than they would for a southern exposure.
Intensity of light
In addition to color, the power of the light source can also affect the perceived colors of objects it illuminates. Brighter isn’t always better, though. Research from the Lighting Research Center has compared the relationship of efficacy to CRI, gamut area, and full-spectrum color index values. Sometimes very bright lights, for instance high-pressure sodium lamps, scored poorly on color rendering. Depending upon the application, color might be more important than brightness.
The following Datacolor blog posts also discuss the relationship between light sources and color:
- How Different Light Sources Affect the Way We See Color
- Implementing a New Light Source? Here’s What You Need to Know
Backgrounds and color
Colors can appear quite different depending upon their context – not just the brightness of the viewing area, but the relationship between a color sample and its background. The Datacolor blog When it Comes to Color Why Can’t We Agree? provides examples of optical illusions in which colors appear different depending upon the density or color of the background.
Five additional examples of color illusions show why it can be so difficult to match colors accurately. Even when variables are as tightly controlled as possible, color perception is variable and subjective.
Color perception has been shown to change in high altitudes. One study evaluated the effect of reduced oxygen levels that create physiological changes in the eye. Another found that vision changes climbers experienced at high altitudes reversed themselves within a short time when the subjects returned home.
The relationship between sound and color has fascinated scientists for hundreds of years. Plato and Aristotle speculated about the relationship between color and music, and Sir Isaac Newton styled his color wheel to correspond to the musical scale. Synesthesia is a well-known condition whereby people can hear colors (or experience other crossed senses).
But while sound can trigger a color, it’s not clear whether sound – especially noise – can suppress color perception. One study measured “hue bias” associated with several factors, including noise, and did see a relationship. Another study indicated that bursts of white noise could suppress visual perception generally, but it didn’t single out color perception.