Subtractive colours

Subtractive colours start with light, presumably white light. Coloured inks, paints absorb some wavelengths of light and reflecting or transmitting others. The three primary subtractive colours are yellow, magenta and cyan.
The yellow pigment absorbs blue light allowing red and green to pass through reflecting from its surface. We perceive the red and green light and see yellow.
The magenta pigment absorbs green light allowing red and blue to pass through or reflect from its surface. We perceive the red and blue light and see magenta.
The cyan pigment absorbs red light allowing green and blue light to pass through or reflect from its surface. We perceive the green and blue and see cyan.
Yellow ink absorb blue light, cyan ink absorbs red light. The only light that remains is green. Green is the subtractive secondary colour achieved by mixing two primary.
Yellow ink absorbs blue light, magenta ink absorbs green light. The only light that remains is red. Red is the subtractive secondary colour achieve by mixing two primary.
Magenta ink absorbs green light, cyan ink absorbs red light. The only light that remains is blue. Blue is the subtractive secondary colour achieved by mixing two primary.
When all three light are in the mix all three lights are absorbed (blue, green, red) therefore we cannot see any light in effect see black.
Yellow + Magenta + Cyan = Black
The printing industry use CMYK colour space, K representing not quite black = when all 3 subtractive colours are combined.


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Additive colours

Additive colour system starts with darkness. Light source from various wavelength is added in various proportion to produce a range of colours. Additive colour theory describes how we perceive color and how they are created. It is essentially colour created by mixing light of two or more different additive colours. The three primary additive colours are red, green and blue, otherwise referred to as RGB
Red & Green = yellow
Green & Blue = cyan
Red & Blue = magenta

Yellow, cyan and magenta are secondary additive colours. When all 3 primary colours and mixed it added together it creates white light. Computer monitors and television are most common examples of additive colours.


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Jonannes Itten – colour contrast

Johannes Itten was a Swiss painter, designer and teacher born in 1888 – 1967. Itten was one of the first people to identify strategies for successful colour combinations resulting in striking colours and contrast. His teaching explained seven methods for coordinating colours utilizing hue’s contrasting properties.

1. Contrast of saturation – this is the contrast between luminous and dull colours.
2. Contrast of light and dark – is the difference in brightness and tone values of colours, which can be lightened with white and darkened with black.
3. Contrast of extension – is based on the relative areas of two or more colours, such as large and small.
4. A complementary contrast – exist when two complementary colours are placed side by side.
5. Simultaneous contrast – is when the opposite colours are placed side by side creating the illusion of vibration or shadows.
6. Contrast of hue – is when pure colours are used in random combinations, which can be further enhanced with black and white.
7. Contrast of warm and cool – is created when warm colours (red, orange, yellow and brown) are place together to evoke a feeling or warmth and comfort. Alternatively cool colours (green, blue, gray) will educe feeling of sadness


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Munsell – Hue Chroma and Value

Professor Albert H Munsell created the Munsell colour system. It is a colour space that separates colour dimension into 3 areas; hue, value and chroma.



Hue measured by degrees around the horizontal circle. Each horizontal circle is divided into 5 principal hues: Red, Yellow, Green, Blue and Purple along with 5 intermediate hues – which is halfway between each principal hues.  There are now in effect 10 sub colours (red, yellow red, yellow, green yellow, green, blue green, blue, purple blue, purple, red purple). Within the 10 sub colours there are 5 hues = in total there are 100 hues separated in increments of 2.5.
Value measures the lightness; black (value 0) at the bottom and white (value 10) at the top. There are several colour solids and gray gradient in between.
Chroma measures the purity of a colour (saturation) with the lower chroma being less pure and appearing washed out, otherwise known as pastels.
Munsell colouring system is also referred to as the number theory. By identifying each colour with a universal number we can produce an accurate representation and of the colour pallet.

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Goethe – the psychology of colour

Colour is an essential part of how we experience the world both emotionally and culturally. In 1810 Johann Wolfgang von Goethe; a German writer, artist and politician published a book titled Theory of Colours.  He focused on the psychological aspect of how brain interpret colours and influence our emotions. Certain colours or colour combination create certain mood and feelings. He base this theory on the colour wheel designed by Isaac Newton and explained that there are ‘positive’ and ‘negative’ colours. Positive are also viewed as warm colours (yellow, orange) and negative are the cooler tones such as blue and purple.

He further elaborates of the different colour combination that could create certain atmosphere. Gentle – by mixing 2 negative colours we could potentially design a calm/ cold environment. For example a room filled with green and blue one would feel relaxed. Powerful – by mixing 2 positive colours we could potentially design a warm and lively environment. Yellow and orange creates an upbeat feeling. Radiant – by mixing a negative and positive tone.


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Isaac Newton – Prism Theory

Isaac Newton is an English physicist and mathematician; his work was influential in many key areas, which include the law of motion, the law of gravity and his contribution to optic. In 1672 he published the theory on spectrum of light. In this experiment He passed a beam of sunlight to a glass prism, which refracted light to the opposite wall producing beautiful and vivid colours. He noticed that colours separating due to some hue refracted more than others eg: blue more so than red. His theory showed that light alone is responsible for colour. Colour is the result of light and not in the glass. He developed conceptual arrangements of colours in which artisan use as primary and secondary. The light that we see as white is a mixture of all the colours of the visible spectrum.


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Aristotle – Theory for Rainbow Formation

A rainbow is an optical phenomenon; it is visible whenever there are droplets of water in the air and sunlight shining from behind. In about 300 BC a Greek philosopher Aristotle devoted much time understanding the theory of rainbow formation. His main idea is when ray of sunlight hit points in the raincloud they all deflective back at a fixed angle. As rays of the sun are parallel to each other they will deflect at the same angle at all points of the clouds. He used geometry to explain this theory ascertaining that if the ground is not in way we would see a full rainbow circle however with shadows in the way that is why we see an arch shape. There is no fixed point in the sky to locate a rainbow; its position is dependent on the observer’s location and the position of the sun. When we move our visual optic of the rainbow moves, with this in mind the myth of ‘pot of gold at the other side of the rainbow reminds a myth.


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