8 Examples of a Spectral Color

John Spacey, July 26, 2020

A spectral color is a color that corresponds to a pure wavelength of visible light. All colors are formed with mixes of spectral colors such that they are the root of all color. Spectral colors correspond to wavelengths of light and are theoretically infinite as you could continually measure smaller and smaller differences between wavelengths. Traditionally, these are separated into eight different color names by wavelength as follows.

Color	Wavelength (nm)
Violet	380 - 430
Indigo	430 - 460
Blue	460 - 500
Cyan	500 - 520
Green	520 - 565
Yellow	565 - 590
Orange	590 - 625
Red	625 - 740

Millions of perceptible colors can be made by mixing the various wavelengths of light above in different combinations and using different light intensities. The practice of breaking the range of visible light into eight named ranges is cultural or technical such that it can be done in different ways. For example, it is common to merge the indigo range above into blue. The following is a visualization of the entire range.

Spectral Color vs Primary Color

Spectral colors are based on the science of light perception such that they map to the physics of light that can be perceived by humans. Primary colors are a set of colors defined by a color system that can be used to simulate all other colors. The following chart illustrates the difference between these concepts.

	Spectral Color	Primary Color
Based On	Science	Art & Technology
Represents	The physics of light that can be perceived with the eyes.	A system for simulating all colors with a small set of colors.
Can reproduce all colors?	Yes	No, some colors are only simulated with primary colors such as red, green and blue (RGB). You need all spectral colors to truly reproduce all colors.
Usefulness	Understanding color	Implementing a technology or painting method that simulates a wide range of colors.
Notes	There is only one set of spectral colors.	There are many different sets of primary colors corresponding to different technologies and painting methods.

Notes

Although spectral colors are the root of all colors, other factors impact color. For example, light intensity can be used to make colors light or dark.

Visible light is a tiny part of the electromagnetic spectrum that includes extremely shortwave lengths such as a 1 picometre gamma ray all the way up to a extremely low frequency radio wave that is 100,000 kilometers long.

8 Examples of a Spectral Color

Spectral Color vs Primary Color

Notes

Color Theory

References

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