We explain what primary colors are and how our eyes perceive them. Also, what is the subtractive synthesis of color.
What are primary colors?
Primary colors or primitive colors are those colors that cannot be obtained by mixing other tones or colors, but are "pure", contained in the light white and inside visible spectrum for the human eye. Red, blue, and green are commonly considered primary colors.
However, it is not that primary colors are a property of light, nor that they are defined within it. Actually, the electromagnetic radiation that we call "light" is made up of a continuous range of wavelengths, in which there may well be an uncountable number of colors, but of which the human eye, due to its biological configuration, can capture only some.
In our eyes there are ocular receptors (cones L, M and S), capable of identifying red, green and blue light, from which the rest is composed, thanks to an additive color system. Thus, with the red-green-blue triad (RVA, often called RGB for its acronym in English), the following can be obtained:
- Cyan, adding green + blue.
- Magenta, adding red + blue.
- Yellow, adding red + green.
- White, adding red + green + blue.
This process of mixing the intensities of light is known as additive color synthesis. This name is due to the fact that each color mixture brings light, that is, as primary colors are mixed, one advances towards white (all colors at the same time).
The subtractive synthesis of color
Subtractive color synthesis is called another theory of pigment mixing that, contrary to additive synthesis (in which each color mixture contributes light intensity), subtracts or subtracts light intensity from the resulting color with each color mixture. In other words, when mixing colors, light is lost, one moves towards black.
The primary colors according to this specific synthesis are cyan, magenta and yellow, so it is known as CMYK for its acronym in English (Cyan, Magenta, Yellow & Black). Thus, adding primary colors can be obtained by subtraction:
- Red, adding magenta and yellow.
- Blue, adding cyan and magenta.
- Green, adding cyan and yellow.
- Black, adding cyan, yellow and magenta.