Tuesday, July 15, 2008

Complementary Colours and mixing neutral colours

Complementary Colours are conventionally described as colours which are on the opposite sides of a colour wheel. However, as I demonstrated in Describing a colour space - there's more than one colour wheel! more than one shape has been used to describe colour relationships in space
- and there's also more than one colour wheel. So how do you work out what are complementary colours?

An exercise in mixing neutrals from 12 complementary coloursusing coloured pencils
(from Stephen Quiller's book -
Color Choices: Making Color Sense Out of Color Theory

Wikipedia provides a more accurate way of describing complementary colours.
Complementary colors are pairs of colors that are of “opposite” hue in some color model. The exact hue “complementary” to a given hue depends on the model in question, and perceptually uniformadditive, and subtractive color models, for example, have differing complements for any given color.Wikipedia - complementary color
Just one problem with that definition - which is that Wikipedia hasn't yet got round to producing an article on 'perceptually uniform' - although I think what it is referring to is partitive models of colour theory - which are all about the perception of colour.

How to identify complementary colours

So, in summary, in order to identify complementary colours
  1. decide what sort of colour mixing you are talking about - additive, subtractive or partitive
  2. identify which model of colour theory you want to use
  3. identify the colours which are opposite in that theory!
As artists we need to to focus on
  • the subtractive models - in relation to the mixing of paints
  • the partitive models - in relation to how we perceive colour - and how
    colour behaves when it is used in an artwork, For example how it reacts
    with the colour of the ground or how it responds to colours placed next to it)
  • the additive models - to understand how light behaves - and why colours in
    artwork don't always look the same when seen on a screen.

How many complementary hues in pigments and dyes?

Complementary hues partly depend on how many colours you want to identify in your colour model. With only a few colours then identification of the opposite hue can only be approximate.

In a 12 colour pigment wheel the complementary colours are:
  • yellow and violet
  • yellow green and red violet
  • reen and red
  • blue-green and red-orange
  • blue and orange
  • blue-violet and yellow-orange
In a 6 colour (ink) process wheel the complementaries are:
  • yellow and blue
  • red and cyan
  • magenta and green
In a colour perception model, the complementary hue is thought to be the colour you see or perceive through negative after images due to the opponent process.
Ewald Hering explained how the brain sees afterimages, in terms of three pairs of primary colors. This opponent process theory states that the human visual system interprets color information by processing signals from cones and rods in an antagonistic manner. The opponent color theory suggests that there are three opponent channels: red versus green, blue versus yellow, and black versus white. Responses to one color of an opponent channel are antagonistic to those to the other color. Therefore, a green image will produce a red afterimage. The green color tires out the green photoreceptors, so they produce a weaker signal. Anything resulting in less green, is interpreted as its paired primary color, which is red.
Wikipedia - after image
Goethe arranged his color wheel symmetrically,
"for the colours diametrically opposed to each other in this diagram are those which
reciprocally evoke each other in the eye. Thus, yellow demands violet; orange, blue; red, green; and vice versa: thus... all intermediate gradations reciprocally evoke each other."
Wikipedia - opponent process and Goethe's Colour Theory

What happens if you mix two complementary colours? (Part 1)

What happens if you mix complementary colours?
  • If you mix all colours together in the physical of light/additive model you get white light - the result of reflecting all the colours in the spectrum
  • If you mix all colours together in the pigment/subtractive model of colour you should get black (the absence of reflected light)

Coloured greys

However if you mix two complementary hues you achieve a neutral coloured grey. Some of the coloured greys which can be achieved using coloured pencils are set out in the colour chart above. This colour chart was produced using an exercise from my Stephen Quiller book Color Choices: Making Color Sense Out of Color Theory. (12 colour version on page 19 - with a 16 colour version on page 43). If you want to buy a book about exploring complementary colours then this one comes highly recommended by me!

The Jeanne Dobie book Making Color Sing is also great on the topic of colour mixing and, in particular, at for explaining the power of what she calls the 'mouse' colours (coloured greys).

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In Quiller's exercise he demonstrates, using watercolours, how all the primary, secondary and tertiary colours on his colour wheel grey each other out. (These are what Jeanne Dobie calls the mouse colours). I wanted to see what would happen if I used this method of mixing colours using coloured pencils - and was delighted with the result! I love the colours in the middle. Bear in mind that I use open hatching when mixing coloured pencils which produces an optical mix as well as a pigment mix - more about this later in this post.

Quiller calls the pure mix of the two complementaries the 'neutral'. The 'semi-neutrals' are then the colours which lean more towards one complementary hue or the other. I actually much prefer this as a summary chart which explores the scope offered by mixing complementary colours.

In principle, the neutrals and semi-neutrals are contained in the inner rings of a colour wheel. However the problem with this model of displaying such colours is that you don't get to see very much of them - hence why I prefer the matrix approach.

A summary of principles for colour mixing

What follows is a summary of basic principles relating to colour mixing. These relate both to mixing perceived hues and mixing pigments. Both are relevant to art and how colour can be used in artwork.........

Optical mixing is when colours are mixed by the eye; the colours are juxtaposed in term of paint upon coloured ground or two colours placed next to one another. Pigment mixing is when hues are mixed on the palette prior to their application to a support.

Optical mixing of colours - colour perception; the juxtaposition of colours on the support)

  • the Law of Simultaneous Contrast (Identified by Michel Eugène Chevreul and documented in The Principles of Harmony and Contrast of Colours - see link at end for pdf file of a book which became the bible of French and American Impressionists)
    • two complementary hues of a pure colour placed side by side will always excite and brighten one another in the eyes of the viewer.
    • The level of contrast - in both tone and colour - and excitement it creates draws the eye of the viewer.
  • Complementary Colour balance #1: Equal amounts of the same complementary hue (or value or chroma) compete for attention and confuse the eye which zips back and too between the two colours trying to work out which is dominant.
    • work out which hue is dominant
    • work out which value (of each hue) is dominant
    • work out which hue has most luminance
  • Complementary Colour balance #2: Complementary Hues balance one another however complementary hues do not need to be equal to balance one another.
    • The balance usually relates to the where the hues rank in terms of chroma or intensity.
    • For example, a small amount of red (a very intense colour) always stands out in a sea of green (a less intense colour). Paintings of poppy fields engage our attention for a reason!
  • Complementary Colour balance #3: Just as you need darks to see lights; you also need grays to properly appreciate the intensity of the contrast of complementary hues. A viewer's eye benefits from having areas where it can rest and actually avoid the intensity of juxtaposed complementaries - hence the proportion of neutrals and semi-neutrals to juxtaposed complementary colours is very important for creating balance and allowing the full intensity of colour to shine through (Both Quiller and Dobie provide excellent demonstrations).
  • Colour in Shadows and Reflections: An object of any given color will cast a shadow tinged with its complementary color - hence the interest of Impressionists in painting light....and shadows (Shadows are never black - they are always coloured)
  • Times to think about complementary hues and coloured grays/neutrals
    • when creating a coloured ground,
    • when underpainting or overpainting
    • when painting alla prima (using broken colour)
    • when using pointillism (see Seurat ) or
    • when glazing

Mixing pigment colours (physical mixing of pigments on palette)

  • Mixing a colour with its complementary always neutralises the colour - it makes a colour duller and less intense
  • Mixing a colour with equal proportions of complementaries tends to produce a muddy neutral value
  • Hues produced through mixing complementary hues will always sit well with and/or next to the complementary hues from which they were derived (which is why paintings using primarily complementary hues - and all their derivatives - have a sense of unity)
Quiller provides excellent examples which explain visually how colour balance can be achieved - and how to organise hue, value, and chroma so that there is clarity as to which is dominant and why neutral hues are important.

What happens if you mix two complementary colours? (Part 2)

Before mixing complementary hues you need to think about which colours to use. For example, you might think that the complementary of blue is orange - but what sort of blue and what sort of orange?
Here's what a colour scale looks like if mixing one orange with a range of blues which sat near one another in the pigment spectrum.

Orange, a few analogous blues and associated neutrals
copyright Katherine Tyrrell

I didn't use the range of all possible blues - but rather used analogous blue hues. (I'll be covering analogous colours later this week). See how all the blues are slightly different and all the neutrals and neutral tints are also slightly different. This is because some blues lean towards green (and yellow) while others lean towards purple (and red). Holding the secondary colour of red as standard can produce subtly different colours depending on which blue is used.

For me it also demonstrates how despite the fact that all the colours had different names I think it's more or less certain that some of them had very similar pigment combinations. For coloured pencils, it emphasis the need to know an awful lot more about what are the pigments/chemicals which are used in each colour.

I always hatch my colour squares and in the neutrals and neutral tints you can see some of the the colours vibrate together in some of the squares. The same thing is happening in the colour chart at the top of the page.

An amusing aside

Check out this explanation of complementary colours from The Artist's Toolkit. Click the arrow and try the exercises if you want to practice finding complementary colours.

What comes next?

Analogous colours is the next post in The Colour Project. For more information about previous posts see the links and information sites below.


The Making A Mark Project on Colour - previous posts

My Resources for Artists information sites 

  • Colour - Resources for Artists  moving to my new Tips for Artists website
  • Colour - Art Book Reviews for Artists still live - but also moving to my new Tips for Artists website
  • Colour science, systems and models - Resources for Artists mo
  • moving to my new Tips for Artists website