Color Theory

In this tutorial I will try to explain the basic rules of working with colour. Heh, that's a really tough task, so be understanding and gentle ;). I urge anyone that reads this article to paint and make observations as you go along, even copy the images as closely as possible to learn. Have fun. That's, what's Art about.
 

Part 1 : "RGB" - what's that?

The RGB stands for "Red, "Green" and "Blue", the main colours in the palette. By mixing these colours you can achieve thousands of colours. The standard is used in TV's and monitors for example. It's used for any imaging device that has a screen. There are also other standards, like CMYK (Cyan, Magenta, Yellow, blacK) but this one for ex. is used for printing. But the most common standard is RGB and this is what we'll talk about.

Why "RGB"?

The white sun light is made of different colours, it's not really white; when you throw the sunlight thru the prism or thru the drops of water (a rainbow), the light will split to all the colour components of the light - that is Purple, Red, Yellow, Green, Blue Cyan, Dark Blue. Newton and Young made experiments, that prove this fact. And it was Young that proved, that the amount of the components can be diminished to three - Red, Green and Blue, that we will call Secondary colours. Those three colours allowed Young to recreate the White light. The Primary colours (Purple, Yellow, Cyan) are made by mixing the Secondary Colours. Mixing Primary with Secondary colours will give us Thertiary colours, and so on and so forth...

(on the illustration - P-Primary colour, S - Secondary, T - Tertiary)

Part 2 : Mixing Colours - live (Read only when you painting with real paints or want use mixer in Painter)

Yeah, you say, I mix red, green and blue paint and all I get is black. Yes, when we mix paints we will not get a brighter colours as it happens with the light (Synthesis by Addition), but darker.
(mixed red, green and blue colours in Painter)
 

This is called Synthesis by Substraction. It works like that  - when you mix cyan with yellow, you get green, because when the light is cast on it, the cyan substracts red, the yellow substracts blue... and comes out green (image 2, bottom) when the white light is cast on the mix. In spotlights when you mix red with green - you'll get yellow, because is adds one to another ( image 1 - middle left ). This info is usefull, when you have to light some scene in a theatre or 3D.
(1 - Synthesis by Addition; 2 - Sythesis by Substraction)

By understanding it we can simulate the natural colours of the world, when painting non-digital.

Part 3 - Filling colours

That's always a problem - what colour put next to another so that it looks good? This is a task for a lot of time, mainly learning by your own experience, BUT... there is a very simple rule that covers it - when you take a colour wheel, the filling colours lie opposite each other (yellow - deep blue, red - cyan etc).

By understanding it and using it well you can create very intensive shadows and background and create amazing contrasts. 

(Henri Matisse -

(Henri Matisse -

Part 3 : Colours of objects

Every object has a colour, and can be defined by one. But we have to understand how the object is affected by shadows and surroundings. To make it visible enough let's take a pool ball. When you cast a light on it - you can see that the colour of it is not plain, it has local (true) colour, colour close with tone and surrounding colours (reflection) and specular highlight.

(1 - specular highlight, 2 - local colour, 3 - reflections, 4 - colour close with tone)

As you can see, the red ball is full of tones. But if you remember the rules of colour interaction - it will be easy for you to rule the colour. The rule of a thumb - most generally we paint shadows by adding black and red to local colour, while adding yellow/green and white to the highlights. This makes nice, deep shadows and bright, live highlights. This situation changes whenever you feel like it - the lighting can get blue, red or of any other colour, affecting the whole scene. The shadows can be cold - blue and lighting can be live and yellow (as on the photos on the bottom). But remember - never make shadows with just adding black to it - it will look ... dirty. I'll prove that later on.

Another thing is the strength of the light. Objects that are lighted with it - especially red and yellow - are well saturated and reflect it very strongly.
  
When the light is fainter - all the objects get desaturated and blue.

(photos taken from H.Parramon book of colour theory)

(photos taken from H.Parramon book of colour theory)

When the atmosphere gets in a way, different situation takes place... The further the planes get from the observer, the more blue and less contrasted they are. It is especially well seen on the landscape photos:

There are also other factors like fog, clouds, smoke etc. that affect the scene. 
 

Part 4 - Contrasts

Comparing to nature our colours are very poor. Imagine a situation - there is a hole in a wall, that leads to a dark room. There is literally no light in it. Then, next to the hole we hang a black sheet of paper. When we compare them - the paper is really dark grey in contrast to the hole.

So we have to immitate the colours by playing with contrasts. The general rule says, that the colour seems brighter, when the surrounding colour is darker. And the opposite - the colour seems darker, when the surrounding colour is brighter.

The same colours of different values put together strenghten each other:

This is a very simple example - each of the stripes is filled with ONE colour of one value - NO GRADIENT, but put next to a colour of a different value, the brighter becomes even more bright, the darker gets even more dark when it meets the other one. On the image you see gradients, that are physically not there, it's just an optical illusion. That's the rule you have to understand - you can strenghten the colour with the value contrast, and you have colour contrast with it too. Also the colour seems different alone than among other colours, so the colours affect each other. The maximum contrast you get by putting together filling colours.
 
Here H. Parramon shows how it is imoprtant to get proper background colours. ON this Francesco Serra painting the background is changed. On the first one - the background is reddish, the contrast makes the olive skin and blouse of the girl more green. That shows the influence of the red background on the character. The second one has more golden background. That makes the girl faint, she dssolves into the back, it makes her less important in the picture, accenting the background. It is heavy and makes the skin colour gray. In both examples the background is also too active, drawing attention away from the girl.

Here we have the original painting, where the background is blue with some tones of green. This is the perfect choice for the background colour, because the filling colour for the yellow is blue. Here also artist made a contrast of values - where the skin is light - the background is dark, where the skin is dark - the opposite - look at the hair at the forehead, the neck, the arm. Thru the contrasts he takes the character out of the portrait into the first plane. He also accents the girl with the black outline. Notice also the presence of the filling colours in shadows on the blouse - they are green, and the blouse is faint blue in some places. The artist always thought of the filling colours while painting that.

So to sum up - with one brush stroke you don't paint just a spot, you also paint the area around it (Chevreul)


 

Part 5 - Using black and white, shading

As I said before - the first thing that a man thinks when paints is - to make it lighter I have to add white, to make it darker - black. Well, not exactly. Let me show you.

On this quick sketch you can see shaded bucket (let's just say that you see it). Looking at a first glance it's OK. But only OK, something is missing.

Here is a bucket with good colouristics. Here greater number of colours were used, the bucket looks more 3 dimensional, the filling colour is used in the shade to liven up the picture (to have a yellow background and blue shadow is not possible, but I used it to show you how can it be done and what it does with the picture). It looks much more alive and natural. The one above looks dirty, because it was shaded just with using black and white. For a better understanding compare the highlights. So - when it's possible - don't use white.

When painting, you have to always be aware of the surrounding environment, that can affect the thing that you paint. You have to observe, if the lighter areas are affected with blue, red or yellow colour... The shadows can also have dominant red or blue, as these are the darkest colours in the light spectrum. And be aware of what you want to show, what you want to accent. Overall it is common to use more desaturated colours, using live colours just to accent something you choose to be important in the picture.
 
Well, that's about it for a beginning. There are also some things to say about harmonizing the colours, tonations and rules about using them, but it's more advance. I'll write another tutorial covering those subjects, so stay tuned.

Michal Matczak, Moderator and Texture Artist for 3d Total.

To see more by Michal Matczak, check out Prime - The Definitive Digital Art Collection

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