Color theory

All about design, from A-Zee

CMYK, RGB, Additive, Subtractive, Primary, Secondary, Tertiary…what does it all mean???

Well at the base level these terms all refer to categories of color. 

But isn't all color the same? Blue is blue and red is red, right?

Not quite. When looking at a specific color, take blue for example, we might think it appears the same to us regardless of where we see it - in nature, on tv, in print, etc. However, how that color of blue is generated for each of those specific environments is entirely different. Understanding how these colors are created and the visual effects they engender is a concept known as color theory. This is a topic that would take pages and pages, and hours upon hours to discuss completely. For now I will endeavor to cover the basics, and will expand upon the various points of color theory in more depth in subsequent posts.

Defining terms - primary and secondary

Crayola crayons. ©Stephenie Koerne

Crayola crayons. ©Stephenie Koerne

In order to better understand what color is exactly, lets start by defining CMYK, RGB, additive, subtractive, primary, secondary, and tertiary. The easiest of these is the traditional or historical primary and secondary sets - these are the colors that are first learned as a child, clutching our brand new box of Crayola crayons. 

Chromatography or A treatise on colours and pigments: and of their powers in painting, 1841. By George Field [Public domain], via Wikimedia Commons

Chromatography or A treatise on colours and pigments: and of their powers in painting, 1841. By George Field [Public domain], via Wikimedia Commons

The primary colors (RYB) are red, yellow, and blue. From these three base colors, we can create all others. By combining two primary colors in equal amounts, we are able to get our secondary colors (VOG), violet/purple (red + blue), orange (red + yellow), and green (blue + yellow). Note, many people use violet and purple interchangeably.

The traditional primary and secondary colors are used in the fine arts, particularly in design and painting.

From there things can get a bit more complicated.

DanPMK at en.wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons

DanPMK at en.wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons

A modern scientific theory argues that the traditional primary colors are actually not the best set for obtaining the widest range of colors. For that we need to look at the second set of primary colors, CMY(K) - cyan, magenta, and yellow. From these we can get our traditional colors, which can vaguely be thought of as the CMY secondary colors, and the third set of primary colors, red (magenta + yellow), blue (cyan + magenta), and green (yellow + cyan). The K in CMYK refers to black, which we will discuss shortly.

Wait, what, a third set of primary colors? Yep, RGB or red, green and blue is another set of primary colors. And from these we can get the RGB secondary colors, cyan (blue + green), magenta (red + blue), and yellow (red + green).

Tertiary and beyond

Now if that isn't all clear as mud, lets discuss what lies beyond primary and secondary colors.

Tertiary colors are created by combining adjacent primary and secondary colors. For example with the traditional primary and secondary colors our tertiary colors would be vermilion (red + orange), amber (yellow + orange), chartreuse (yellow + green), teal (blue + green), violet (blue + purple), and magenta (red + purple). Note, this magenta is not quite the same as that found in the CMY color set.

The tertiary colors for the RGB and CMY sets are azure (cyan + blue), violet (blue + magenta), rose (magenta + red), orange (red + yellow), chartreuse (yellow + green), and spring green (green + cyan).

Another group of tertiary colors can be created by mixing secondary colors. From those resulting colors we can then get quaternary colors, and from those we can get quinary colors, which are, roughly, varying shades of gray. 

Color + or - (or additive and subtractive colors)

Additive colors are are the primary colors of light - RGB. Subtractive colors are colors of pigment - RYB and CMY. 

By Zátonyi Sándor (ifj.); Fizped (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

By Zátonyi Sándor (ifj.); Fizped (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

So what does that mean, colors of light, colors of pigment? Well, quite frankly, it means exactly what it says. RGB are colors perceived when mixing (adding) light as it is emitted through media such as tv or video displays. While RYB and CMY are colors that are created through media, such as paints and dyes, in which light is absorbed (subtracted). The additive color system takes us from dark to light, while the subtractive system takes us from light to dark.

A very simplistic, and practical, way that I like to remember the difference between the two, is that, additive colors are visual, while subtractive are physical.

It's all black and white to me…plus gray and brown

In all of this talk about color, where exactly does black and white come in? Not to mention gray and brown.

As I mentioned earlier, the K in CMYK refers to black. In the subtractive color realm, black is the absence of light and is created by combining cyan, magenta and yellow. In the additive realm, black is created through the absence of color (no other colors emitted/showing).

In additive color mixing, white is achieved by combining the red, green, and blue. While in subtractive color mixing, white is the absence of color.

The creation of gray and brown starts to get a bit more muddy in that there are many different combinations that can be used to achieve the colors. 

Moving forward

As stated at the beginning, color theory is a huge topic and to understand it completely, you have to discuss is in much further detail, defining terms and concepts such as hue, saturation, complimentary, achromatic, gamut, Pantone, etc., etc., etc. But that is all to be discussed at another time. Keep checking back here, for more posts breaking down the wondrous world of color.

'Til next time!


Stephenie Koerne is a Digital Media Lab Instructor at the UW Stratford Campus, but better know as Jill-of-all-Trades. When not juggling work tasks, Stephenie wiles away the hours working on her photography and other art projects, collecting toys (as showcased in her office!), and reading. She loves cats and pink is her signature color.

P.S. Stephenie is American, so her blog series is Design A-Z, not A-Zed, and no there is not supposed to be a U in color.