Theory Thursday #1 - The full Color Wheel

Welcome everyone to the first Theory Thursday!

If you are not interested in understanding how the world works, especially light and shadow, color and harmony, you should better skip reading this post and future Theory Thursday editions.
Opposed to the very direct and practical tutorials you will usually find here, these series of posts will go in depth to answer questions that many painters didn't even ask themselfes.

Be reminded that these posts are written by Raffa alone and reflect his understanding of the topics.
He is not always right and if you found an error or you want to discuss, use the comment section!

We will start with very basic stuff and will advance more and more into the depth of physics.

This week the topic will be:

Why is the color wheel a full circle?

This sound strange at first as most of us are used some kind of color wheel.
The color wheel is our friend, how can anything be wrong with him?
And why shouldn't the color wheel be full circle as it makes perfect sense the way it is?

Let's start simple at the very beginning of everything, the birth of color.
Color is perceived by a interaction of electromagnetic waves and our eye.
Don't stop reading now even if it sounds complicated at first.

There are a lot of different spectrums of electromagnetic waves, to name a few well known, x-rays, infrared, ultraviolet, radio and tv, microwaves and the one we will be talking about now (and I guess the most important for a painter), the visible spectrum.

Electromagnetic waves are made up of photons. Depending on the power the photon has, it has a different wavelength. This wavelength is responsible for the spectrum in which this photon will be.
A powerful photon will have a short wavelength and can even be harmful (gamma rays - radioactivity). But let's move away from photons as this may be interesting, but it's a really deep topic and won't bring us any closer to answering the question of the color wheel! We will talk about photons and electromagnetic waves in a later edition of Theory Thursday.

The visible spectrum is the area of electromagnetic waves that are visible to us.
It begins directly after ultraviolet with violet/blue and ends with red before infrared.

Did you ever see a rainbow? I hope so, otherwise your life would be very sad and you should start searching for a rainbow immediately! Rainbows are a joy to look at and you can hear people go "ahhhhh" and "ohhhh" when they see one. Especially true for double rainbows - with all those colors.
Some people even say there is gold at the end of a rainbow but I tried to find it once and there was only unicorn poo.
However a rainbow is a good example of the visible spectrum of light.

image from Wikipedia by Takkk

Same for a prism, maybe you saw one in physics class in school. Probably it was very boring back then. A prism splits up light into single wavelengths of visible light.

image from Wikipedia by Spigget

We see the visible spectrum which is this

image from Wikipedia by Deborah S Krolls

Maybe you already noticed something by now.
If not take this color and try to find it on the visible spectrum.

MAGENTA! Magenta, the connection between Red and Violet. Closing the Color Wheel and making it a full circle. Without Magenta it wouldn't be a full circle.
But how can it be?
How can we see a color that doesn't exist as a photon?

Magenta isn't a physical color, it's a physiological color.
We can see Magenta because of our brains are awesome and found a solution for a problem.

To understand how we can see Magenta and why we see Magenta we have to understand how the eye and brain works.

Let's skip this whole boring lens-inverting-image-focus-image bla bla stuff and let's focus on color.
You can see different colors because of little cones inside your eye. (They also make you able to see the brightness levels AT DAY. There are also rods, those help you to see in the dark and see motion and peripheral vision, we will also talk about rods in the future and the influence of them on colors at night).

Those cones are split up into three different kinds, Red, Blue and Green resembling the primary colors. 

Red is a very strong cone, he has many brothers that make up the majority of cones in the eye.
Blue is always sad, he has only very few brothers (2% of the eyes cones are blue) and beeing blue all the time is - not - cool!

Maybe some of you already yell at the monitor...
"You LIAR, those are NOT the primary colors!!! It's Red, Blue and YELLOW!"

So let's do a short excursion into the world of primary colors.
Well, the primary colors depend on the medium and the way they mix.
Let's start with the primary colors we all (hopefully) know.
The primary colors for painting, printing etc.
The subtractive mixed colors.
Red, Blue and Yellow... well almost! Did you ever look inside your printer?

 image from Wikipedia by DragonLord

Those are the 'real' primaries for mixing subtractive colors.
Magenta, Cyan and Yellow (Black is basically just a money saver...).
Legends say you can mix any color using these three primary colors.
And it's actually not that far from reality.

You can mix basically all colors with these three primary colors.


Now, opposing to this, lightwaves are mixed additively, the primary colors are Red, Blue and Green.

If you don't believe me, go closer to your monitor and you will see small primary colored lights.

image from Wikimedia Commons by Luís Flávio Loureiro dos Santos

Click on this image to zoom in and see how individual pixels create all the colors on your monitor.

And how does our Brain interpret what colors we see?
Imagine the three color cones beeing hit by light in a certain wavelength.
For example pure red.

The red color cone will completely explode from excitement while blue and green are completely bored by the color and not stimulated at all. RED! RED ALL THE WAY!!!

Now let's hit the cones with some yellow.

Yeah! Exactly how you already guessed, Green and Red are having a great time, both are equally excited and blue is still sad and lonely.

If you look at the additive mixing circle, you will notice that if you mix all three primaries, we will get white.

Yay, BFF!

Objects in the real world absorb certain wavelengths and the rest, the spectrum that isn't absorbed will be the "color" of the object. So a banana basically absorbs all colors except yellows, an apple absorbs all colors except red and so on. This determines the color of an object.
If an object reflects the whole spectrum, the color we will see is white.
Because all of our color cones are stimulated our brain interprets that it must be white.
white light containts all colors of the visible spectrum.
Oh, and black means, no light is reflected/received at all.

Ok, let's stop with all these super-obvious examples and let's find out about friggin Magenta!

If you look at the additive mixing table, Magenta is a mix of blue and red, so when both wavelengths hit the cones at the same time, the brain has to know: is it something BETWEEN Red and Blue on the visible spectrum which would be Green, OR is is just Red and Blue without anything in between.

An Example:
If the Red Cones and Blue Cones are stimulated about 70% AND Green Cones are stimulated 100%, the color must be some bright green.

Now let's remove the Green Part of the color and guess what happens.
Red and Blue Cones are stimulated, but the brain notices a lack of Green stimulation, so it CAN'T be Green.

A Magenta!

Normally the middle between blue and red on the spectrum would be green. But that's (one reason) why we have three kind of cones and not just blue and red. To tell if it is actually green or not.

The Brain makes a new color to tell us if it is Green or not, you could basically call Magenta the "Anti-Green".

 Or is Green 'Anti-Magenta'?

It's basically a way of our Brain to seperate stuff that is purely red + blue from stuff that is kind of greenish. In our survival that was a big thing. Eating a 'Magenta' colored fruit could have a different effect than a bright greenish fruit. Vomiting, dying or beeing exiled by your group of friends for eating strange stuff could be the result.

And with this knowledge it leads to the answer of our question:
Why is the color wheel a full circle?

Because our Brain is awesome!

We really hope you enjoyed this kind of unusual post on Massive Voodoo and if you are thursty for more Theory Thursday (ok, this was a bad one) check Massive Voodoo again next week!

Next week we will have the following topic:
The Complementary Color Conspiracy

We will also have a further look on how the brain processes the informations collected by the color cones inside the eye. Just in case you think this topic was somehow skipped :)


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