Colours
Have you ever noticed how some colours really go
well together while others don’t? We see colours
together in many situations and being able to choose
which colour goes with which is a very important part
of the design process. While many think that choosing
colours is very much an art, there is an associated
science.
Fig 2 The electromagnetic spectrum
The human eye perceives wavelengths in the range
between range 380-780nm. For example violet is
between 410 and 440, blue 440 and 490, green 490
and 540, and so on.
It is interesting to think about colour when we look at
some of the photographs that are taken in space. Often
space photographs are in a spectrum that is not visible
to the naked eye but which is made visible through
technologies which show us what we could see if we
had a broader visible spectrum.
Fig 1 Colours and fashion
The fashion industry is based on colours that every
season changes colours and couplings.
There are many infra-red photographs to view. Under
normal circumstances we can’t see infra-red spectra
(the wavelength is too large) but other devices can and
these can then be photographed with visible colours.
1. The colour science
The modern understanding of colour originated in the
discovery of the spectral nature of light by Isaac
Newton in the 1600s. Newton considered light to be a
stream of particles. His experiments with prisms
showed that white light can be split into individual
colours. Furthermore, he noted that light of different
colours had different refractive properties. Blue light is
refracted more than red light, for example, when it
passes from air into a medium of higher refractive
index such as a prism. We now know that Newton's
famous experiments demonstrated that light consists of
energy of different wavelengths.
The eye is sensitive to a broad band of wavelengths
with the approximate range 380-780 nm. The visible
spectrum represents only a small fraction of the full
electromagnetic spectrum. Within the visible spectrum
certain wavelengths give rise to certain visual
sensations. For example, the shorter wavelengths are
perceived to be violet and blue. It is important,
however, to understand that the use of terms such as
blue light is for convenience only and that this use is
not intended to contradict the fact that colour exists
only in the mind.
Fig 3 Infrared image from space
This image shown in natural colours was taken with an
infrared camera and translated into visible colours to
enable it to be viewed.
It is interesting to speculate how our minds perceive
colour. It suffices to say that whilst we can recognize
and distinguish colour, our brains interpret the colour
as a consequence of our experience and learning.
Much of the science of colour choice is attributed to
the Swiss scientist Johannes Itten who explained many
of the principles of colour combinations in his 1960
book, The Art of Color. Itten’s work is applied to all
Colours
1
facets of society including interior decoration and
fashion. In his book, Itten explains why people are
more inclined to favour some combinations rather than
others; Itten explored both subjective reasons
(including those related to ancient and modern works
of art) and objective reasons (measurable colour
relationships). He started with the concept of a colour
circle, in which the familiar colours of the rainbow are
stretched into a wheel that encompasses red, orange,
yellow, green, blue and purple sections. Although
earlier colour scientists had explored colour circles,
Itten was the first to realize the harmony inherent in
colour pairs according to their spatial relationships
with one another.
• contrast of extension, which involves the relative
areas or sizes assigned to different colours.
By understanding and applying these different kinds of
colour contrast, the skilled designer or artist can wield
incredible power in shaping the viewer's emotional and
aesthetic response to a graphic, page or image. After
all, many aspects of the colour experience are complex
and easily overlooked, such as the way the light-dark
values of pure colours vary with the intensity of the
light source: Warmer colours look darker in reduced
light, while cooler colours look lighter. These are
precisely the colour effects Itten observed and
explained, and he provides useful suggestions for
taking advantage of them.
Fig 4 The Colour Wheel
The exact structure of the colours wheel has been
discussed by scientists for many years.
For instance, the most fundamental rule of colour
combining is that two colours that lie directly opposite
one another on the colour wheel generally look good
together, a useful guideline when selecting foreground
and background colours in an onscreen presentation or
Web site, for instance.
The effectiveness of colour relationships can often best
be explained with reference to seven distinct colour
contrasts:
• contrast of hue, such as the inherent visual
difference between blue, yellow and red;
• light-dark contrast, from the extreme of night/day
to the subdued effects of neutral grays;
• cold-warm contrast, based on measured human
response to warm colours (red, orange, yellow) and
cool colours (blue, green, brown);
• complementary contrast, found in pairs of colours
that Itten said "require each other, incite each other
to maximum vividness when adjacent, yet
annihilate each other to gray-black when mixed";
• simultaneous contrast, caused by the fact that for
any given colour, the eye "requires" the
complementary colour and generates it
spontaneously if it is not already present;
• contrast of saturation, which relates to the
difference between pure, vivid, intense colours and
dull, pastel, more neutral colours;
Colours
Fig 5 Colour and light
The relationship between colour and light is being
studied in many fields as internal design and museum
design (http://www.studioitaliadesign.com/).
2. The Colour Wheel
In traditional colour theory, there are the 3 pigment
colours that can not be mixed or formed by any
combination of other colours. All other colours are
derived from these 3 hues.
a. Primary Colours
Red, green and blue-violet are regarded as the three
primary colours of light. They stimulate one cone type
and the brain translates this information received by the
eye into what we call colour. When two sets of cones
are fired, we respond that we see for instance yellow a mixture of red and green light. The primary colours
can be seen in the spectrum or rainbow, red at one end,
green in the middle and blue-violet at the other end. In
between these colours may be seen secondary colours
that are, perceptually, each a mixture of two of the
primaries.
2
Thus, you will see yellow between red and green, and
cyan blue between green and blue-violet. The third
secondary colour of light is magenta. This is not part of
the spectrum, it has no single wavelength of light, but
the sensation of magenta may be perceived by looking
at a combination of red and blue-violet light (it can be
distinguished between the two parts of a double
rainbow). It is interesting to notice that, with the
wavelengths yellow and cyan our eyes decompose the
light into responses made by two cones, then our brains
recombine them into the sensation of yellow or cyan.
That is, we never directly perceive yellow or cyan.
A rainbow may be seen by viewing light through a
simple prism. Isaac Newton named seven colours for
his spectrum - red, orange, yellow, green, blue, indigo,
violet. One does not really see indigo as a separate
colour, and orange is a bit doubtful. Newton came from
a culture where specific numbers were regarded as
having mystical significance, so he added the names
orange and indigo to make the magic number seven.
b. Secondary colours
The secondary colours (yellow, cyan and magenta)
appear brighter because two sets of cones are firing
together. These secondary colours are the basic colours
of colour mixing for painting. However, children are
taught crudely that the mixing colours are red, yellow
and blue. This leads to much confusion later if they
become interested in colour work!
To add to the confusion, different people are taught to
match particular colour-names to different colours.
This is particularly true of the blue area. It is sensible
to exercise care when teaching these mixing colours.
Colour printing does not rely on colour mixing, but on
very small dots which are so close to each other that
the eye sees them as a continuous colour. The dots can
be seen through a small magnifying glass.
c. Tertiary Colours
Tertiary colours are a mixture of a primary and a
secondary colour. Thus, red (a primary) and yellow (a
secondary), when combined, are seen as orange.
Conversely, it becomes clear that a green effect can be
obtained either by mixing yellow and cyan pigments or
from a single green pigment and in similar mode for
reds. Of course, all magenta pigments are mixes of two
pigments.
3. Colour Harmony
Harmony can be defined as a pleasing arrangement of
parts, whether it be music, poetry, colour, or even an
ice cream sundae.
In visual experiences, harmony is something that is
pleasing to the eye. It engages the viewer and it creates
an inner sense of order, a balance in the visual
experience. When something is not harmonious, it's
either boring or chaotic. At one extreme is a visual
experience that is so bland that the viewer is not
engaged. The human brain will reject understimulating information. At the other extreme is a
Colours
visual experience that is so overdone, so chaotic that
the viewer can't stand to look at it. The human brain
rejects what it can not organize, what it can not
understand. The visual task requires that we present a
logical structure. Colour harmony delivers visual
interest and a sense of order. In summary, extreme
unity leads to under-stimulation, extreme complexity
leads to over-stimulation. Harmony is a dynamic
equilibrium.
Some Formulas for Colour Harmony
There are many theories for harmony. The following
illustrations and descriptions present some basic
formulas.
Fig 6 Analogous Colours
A colour scheme based on analogous colours
Analogous colours are any three colours which are side
by side on a 12 part colour wheel, such as yellowgreen, yellow, and yellow-orange. Usually one of the
three colours predominates.
Fig 7 Complementary Colours
A colour scheme based on complementary colours.
Complementary colours are any two colours which are
directly opposite each other, such as red and green and
red-purple and yellow-green. In the illustration above,
there are several variations of yellow-green in the
leaves and several variations of red-purple in the
orchid. These opposing colours create maximum
contrast and maximum stability. Nature provides a
perfect departure point for colour harmony. In the
illustration above, red yellow and green create a
harmonious design, regardless of whether this
combination fits into a technical formula for colour
harmony.
4. Colour Context
How colour behaves in relation to other colours and
shapes is a complex area of colour theory. Compare the
3
contrast effects of different colour backgrounds for the
same red square.
colour. Red and green combine to make yellow, green
and blue to make cyan, and blue and red form magenta.
The combination of red, green, and blue in full
intensity makes white.
Fig 8 Contrast effects
Colour perception changes also in relation with the
surrounding context.
Red appears more brilliant against a black background
and somewhat duller against the white background. In
contrast with orange, the red appears lifeless; in
contrast with blue-green, it exhibits brilliance. Notice
that the red square appears larger on black than on
other background colours.
Different readings of the same colour
Looking at the image below you can see that the small
purple rectangle on the left appears to have a redpurple tinge when compared to the small purple
rectangle on the right. But they are both the same
colour and this demonstrates how three colours can be
perceived as four colours.
Fig 9 Colours relationships
Colours are relative if we consider their relationships
and multiple effects that can be created.
Observing the effects colours have on each other is the
starting point for understanding the relativity of colour.
The relationship of values, saturations and the warmth
or coolness of respective hues can cause noticeable
differences in our perception of colour.
5. Colour Models
RGB
The RGB colour model relates very closely to the way
we perceive colour with the r, g and b receptors in our
retinas. RGB uses additive colour mixing and is the
basic colour model used in television or any other
medium that projects colour with light. It is the basic
colour model used in computers and for web graphics,
but it cannot be used for print production.
The secondary colours of RGB – cyan, magenta, and
yellow – are formed by mixing two of the primary
colours (red, green or blue) and excluding the third
Colours
Fig 10 RGB Model
A colour model based on additive colours.
CMYK
The 4-colour CMYK model used in printing lays down
overlapping layers of varying percentages of
transparent cyan (C), magenta (M) and yellow (Y)
inks. In addition a layer of black (K) ink can be added.
The CMYK model uses the subtractive colour model.
Fig 11 CMYK Model
A colour model based on subtractive colours.
6. The Language of Colour
Different colours can evoke different emotions and
different impressions depending on where and how
they are used. If you take the time to notice, it is
possible to see patterns in the ways colours are used
and in the settings where they appear.
• Blue is an energetic colour. It gives a sense of
•
•
•
•
activity and urgency. Blue is used to evoke
emotions of activity, energy and strength.
Red is often associated with eating and food. It is a
colour commonly used in restaurants and eateries in
its many hues and shades.
Pink is s calming colour. Used in combination with
other colours to create peaceful feelings.
Green is the money colour. Often associated with
finance and profits.
Grey is a colour that suggests corporate strength
and business acumen. Grey is found in many
4
public buildings, airports etc. Executives dress in
greys and its various shades.
Considered the negation of colour, black is
conservative, goes well with almost any colour
except the very dark. It also has conflicting
connotations. It can be serious and conventional.
Black can also be mysterious, sexy, and
sophisticated.
http://www.elab.usilu.net/COLORE/demo/index.htm
People often use the language of colour in visual
design to convey impressions and effects. Web pages
are designed with specific colours to carry specific
meanings and intents to viewers.
2. What is a colour wheel? What are some rules for
matching colours using a colour wheel?
•
Colour: Revision Questions
1. What is the electromagnetic spectrum? Over what
range of the spectrum do the visible colours
appear?
3. Discuss and describe colour contrasts that can be
used to choose colour relationships.
4. Which are the primary, secondary colours and
tertiary colours? How are they formed?
5. Explain analogous and complementary colours and
how they are used in colour selections.
6. What is the RGB colour model? Where is it used?
7. The RGB colour model is an additive model of
colour. Explain what this means.
Fig 12 A Web Page
This page uses colour to convey meaning and to evoke
feelings in the user.
Links of Interest
Frequently asked questions about Colour Physics:
http://www.colourware.co.uk/cpfaq.pdf
8. What is the CYMK model of colour? Explain
where it is used and how it differs to the RGB
model.
9. Think of a colour which you like. Write down the
emotions and feelings it evokes in you. Where
have you seen this colour used where you have had
this emotion?
10. Is black a colour? Explain your answer.
Physics designers’ portal with many resources on
colour physic:
http://physics.designerz.com/physics-optics-colour.php
Causes of colours:
http://webexhibits.org/causesofcolor/index.html
The Physics and Physiology of Colour and Colour
Vision:
http://www.greatreality.com/ColorMain.htm
Optical Microscope Primer Website:
http://micro.magnet.fsu.edu/primer/lightandcolour
History of Colour Models:
http://www.handprint.com/HP/WCL/color6.html
A short but interesting tutorial; on how the Hubble
Space Telescope uses colours:
http://hubblesite.org/sci.d.tech/behind_the_pictures/ind
ex.shtml
Online course about colours with some useful links:
Colours
5