The short answer is if you are a painter, you are subtracting your colors, if your are a television set, you are adding your colors. I recently attended an intensive workshop with Jan Hart in Costa Rica. Jan is an expert on color and brought up the subject of additive and subtractive color schemes. I had certainly heard about them over the years, but never really absorbed (pun intended) the real meaning. So, I decided to look into it.
First question you may have is ‘why do I care?’…a good question. We all can operate on the red, yellow, and blue scheme we learned in grade school with great results. Nevertheless, a deeper understanding of how the process works and the differences in the mechanisms that produce color may influence your choices. Who knows, it may ultimately lead to an evolution in your palette that yields more effective paintings.
So here goes….
We perceive light from 1 of 2 types of light source:
- Emitted light such as the sun
- Reflected light such as a piece of watercolor paper
Emitted light, such as light from the sun is additive. White light is all visible wavelengths added together. An absence of light is black. The various visible colors that constitute this white light are visible with a prism or in a rainbow. With the additive color scheme, Red, Green, and Blue are considered the primaries.
Reflected light is subtractive. Huh? Consider a white piece of watercolor paper illuminated by white light. When you paint a red apple, the pigment actually absorbs all of the incoming light except those frequencies that reflect the perception of red. Red is what we see. Hence, all colors except red are ‘subtracted’ from the incoming white light. If we add all our colors to the paper we approach black because more and more frequencies of the incoming light are absorbed by the pigments. Ideally, all colors mixed together would absorb all frequencies resulting in no reflected light, or for us, the perception of black. With the subtractive color scheme, Cyan, Magenta and Yellow are usually considered the primaries. This is why you see these colors in printer cartridges. Printing, painting or anything that uses inks, dyes, pigments etc. to lay color on an object, is subtractive.
The many details of how the primary colors are determined, and how televisions or printers work to provide us with the wonderful world of color go beyond my scope for this short blog. If you are interested in knowing more, the links below are a good place to start. There are endless sources out there on the web to study color perception and color theory.
https://www.rgbworld.com/color.html
http://www.greatreality.com/ColorPrimary.htm
http://www.worqx.com/color/color_systems.htm