Color theory is everywhere—in nature, in cities, in stores, online. We’re so used to it we often don’t notice it’s even there, until we suddenly come across a black and white movie on TV.

Then we remember how good it is that we have such a colorful world. For that reason alone, if not for improving your design skill set, knowing how color works is a good thing to do.

So let’s dive in!

1. Technically, color doesn’t exist

Might sound strange, but it’s true.

Color is created only when our brain tries to make sense from light signals it receives from the outer world. In other words, it’s all in your head.

color theory
Deprived of color, our world would probably look like a scene from Matrix.

Without that, our world is a monochromatic place bathing in electromagnetic radiation of varied intensity and wavelengths. Nothing fun about that, unless you’re into physics.

The key takeout? We should probably have a national holiday just to celebrate the colorful marriage of our eyes and brains.

2. Humans are trichromats

If you ever thought RGB color model is a recent discovery from Silicon Valley, you’d be three centuries off target.

The trichromatic theory—you know, the story saying we see colors through red, green and blue channels—was given birth in 17th century by Thomas Young. I guess they probably considered him mad at the time.

color theory
We are able to see colors because of red, green and blue receptor cells in our retina.

Eventually, science proved he was completely right and explained that we are able to see the colors because we have three distinct types of receptor cells in our retina, each being sensitive to different light properties , or specifically, to red, green and blue color.

Based on that and some other experiments, scientist estimate that we are able to see approximately 10 million different colors.

If that sounds impressive, you might be surprised to hear that we are relatively color blind compared to some species. A Mallard Duck, for example, has 5 types of color receptors in their retina. Might not sound like much but that’s nearly 170% human color vision! When you think about it, Mallard Ducks might be the new X-Men.

3. There are two ways to create colors

Human race loves to fiddle with everything and color is no exception.

During our exploration of color theory, we’ve found there are two ways to go about color creation: by mixing light (or additive) or by mixing paint on paper (subtractive).

Mixing light, or additive model, is perhaps the most intuitive one. It allows you to create colors by mixing red, green and blue light sources in various intensities. The more light you add, the brighter the color mix becomes, which is the reason this mixing process is called “additive”.

Essentially, this is the way we physically perceive colors, and the way we are accustomed to mixing colors through RGB computer model.

color theory
Colors are mixed either by combining light sources, or paint on paper.

But just a few decades ago, subtractive color mixing was the norm and it’s still being taught at art schools. In this case, “subtractive” simply refers to the fact that you subtract the light from the paper by adding more color. Logical, isn’t it?

Traditionally, the primary colors used in subtractive process were red, yellow and blue, as these were the colors painters mixed to get all other hues. As printing emerged, they were subsequently replaced with cyan, magenta, yellow and black (CMYK), as this color combo enables printers to produce a wider variety of colors on paper.

So when you think about it, additive and subtractive color models are just two sides of the same coin, or two ways to think about the same thing: making colors.

4. No single device is capable of reproducing all visible colors

“A device that is able to reproduce the entire visible color space is an unrealized goal within the engineering of color displays and printing processes”.

This is how Wikipedia explains this problem and if you ever had issues trying to match colors on screen with those on paper, you probably have your own words for it.

Technically speaking, every device and printing process has its own color gamut, or a set of colors it can successfully reproduce.

color theory
Same photo, as seen by computer screen (RGB) and typical printer (CMYK). As printer cannot reproduce bright saturated tones, the colors can never perfectly match.

In other words, your color options are limited depending on what you’re working with.

If you’re using RGB screens, you can mix some very bright and saturated colors. If you have to print that out, your options get reduced to a limited color spectrum of a CMYK printer. And, if you saw a brochure printed with a beautiful Pantone colors, you’ll never be able to find them on screen—they simply cannot be reproduced by RGB monitor.

So there you go – different devices, different colors. You’ll never be able to match them perfectly but you can do a lot with some basic color management.

5. We describe colors using color models

“Teal blue” and “Fuxia” are great when you’re talking about sweaters but having a color name for millions of colors we use today would be hardly practical.

That’s why we invented color models or standards which help us describe colors.

color theory
Using HSB color model in Photoshop will make working with color easier, as this color model was invented to help people work more intuitively.

The RGB model

By far the most “popular” additive color model. Each color is described as set of Red, Green and Blue values on a scale from 0 to 255.

The HSB model (or HSL / HSV)

This color model is based on RGB but is better suited to artists and designers. Each color is described as a combination of Hue, Saturation and Brightness values which allows for quick and intuitive color choices.

For example, in HSB model, making an orange color brighter or darker is a matter of playing with the Brightness slider. In RGB model, you’d have to move around all sliders to find a darker tone of the same color,with no clear idea on what you need to do.

The CMYK model

This is standard subtractive, printing color model. Each color is represented by a corresponding value of cyan, magenta, yellow and black inks, on a scale from 0% to 100%.

6. Color wheel is (so far) the best way to think about colors

First invented by Sir Isaac Newton and later improved by countless others, color wheel shows how primary colors blend to create other distinct hues.

color theory
Left: traditional (Newtonian) color wheel consisting of 12 hues created by mixing three primary colors. Right: a fancy computer generated color wheel based on same principles.

Traditionally, the color wheel consists of:

  • Primary colors: Typically Red, Yellow and Blue.
  • Secondary colors: Green, orange and purple hues created by mixing primary colors
  • Tertiary colors: Further color hues you get by mixing a primary color with a secondary color. They are usually named with two words: blue-green, red-violet, yellow-orange.

But why is this useful?

For one thing, it helps you quickly grasp how colors relate to each other and which combinations work best through color wheel harmonies.

7. Colors come in harmonies

How many times have you come across a great design and were impressed with beautiful choice of colors? All things equal, it’s likely that they used one of the rules of color harmonies.

Basic color harmonies
Basic color harmonies

Harmonies are created by picking colors from the wheel according to predefined schemes, such as analogous, complementary or triad. These combinations always look balanced, natural and eye pleasing, just as certain note harmonies in music.

Of course, you should reap the benefits of digital technology and use interactive color scheme applications, such as Color Scheme Designer.

Color theory explained

Color theory is about how color works – the better you understand this, the better designer you’ll be.

Although every bit of knowledge counts, there are three areas you should pay particular attention to: understanding how additive and subtractive mixing works, understanding the gamut (remember – a color spectrum of the device) and handling the color wheel and harmonies.

These three things alone will give you skills necessary to cope with any color challenge in your design career, making you a rare expert in the field.

Have any questions about color theory? Please ask.

Header photo: Rocco Lucia (via Flickr)