Tutorial 88 - Two Types of Color Mixing (Patreon)

Color can mix in two ways, subtractive and additive. How they relate is a very interesting and elegant part of color theory that we’ll touch on here. It's worth knowing, especially if you’re like me and have struggled with color in the past.

Additive color 

Additive color mixing is a system we use to describe the visible effects of combined light sources, before any object reflects the light. It’s the system all of our screens use to create color.

• We start with black, or the absence of light. 
• Then, we observe one or more of the primary colors red, green and blue. 
• When one of these three colors is combined with another, one of three secondary colors is produced.
• The secondary colors are cyan, magenta and yellow.
• White is created when all three primary colors are combined.
• Each pixel on your monitor can emit any one, or combination of the primary colors RGB, and with a range of intensity, to create a huge range of colors.
• We say “additive” because when the wave length that produces the color red, for example, is combined with the wave length that produces green we get “more” light (less filtered) in the form of yellow, we move closer to white. Remember, white is all the primary colors combined.

Subtractive color 

Subtractive color mixing is a system we use to describe the visible effects of combined paint pigments. The color of an object depends on which parts of the visible spectrum it is reflecting. To understand why paint mixes in the way it does we need to think in a subtractive way.

• We start with white, the canvas. 

Note: Red, yellow and blue, or RYB is the set of primary colors we traditionally use in subtractive mixing. This is the standard color wheel we’re all taught in school. But it’s only based on our perceptions, and is considered by some to be old thinking. A more updated model is the CMY (cyan, magenta, yellow) color wheel, which offers a greater range of colors and truer complements. We'll talk more about this and other color wheels (and cubes!) in a later tutorial.

• When one of the three CMY colors is combined with another, one of three secondary colors is produced.
• The secondary colors are red, green and blue.
• Black is created when all three primary colors (CMY) are combined. 
• We say “subtractive” because we are starting with white, which is reflecting all the visible spectrum. Then, when we apply paint, the surface is now subtracting wavelength, producing color.

When we combine these two systems they relate to one another very elegantly. The secondary colors of the additive system are the primary colors of the subtractive system and vice-a-versa. 

It's this interaction that gives us a better understanding of how colors behave and how we can better identify the relationships of colors to each other. We'll explore this a little deeper in an upcoming tutorial.