OUGD401 - Context of Practice Lecture 11

Colour Theory - Systematic Colour (Part 1) - An Introduction to Colour Theory 

Colour is infinite but contextual, meaning what is around it affects how we read the colour.

Physical - Physiological - Psychological

Spectral colour is colour that is evoked by a single wavelength of light with a visible spectrum.
A single wavelength or narrow bands of wavelengths makes monochromatic light.
A wavelength of spectral colour is perceived as spectral colour in a continuous spectrum.
Colours of similar wavelength or close to other wavelengths cannot always be differentiated.

White light is when all the colours come together.
The colours we see vibrate at different wavelengths .
The perception of any colour is based on the eye receiving light that has been reflected from a surface or object.

Black absorbs much of the light.

The sky is seen as blue because the sea is reflected off the particles in the atmosphere, it actually has no colour.

The rods in the eye convey shades of black and white and grey
The cones perceive colour.

There are three types of cone:
Type 1 is sensitive to red - orange light 
Type 2 is sensitive to green 
Type 3 is sensitive to blue

If a cone is stimulated we see that colour.
If multiple cones are stimulated we see different colours e.g green and orange - red = yellow

The eye is 'fooled' into seeing a full range of colours.
Red, blue and green are seen in different proportions.
The way we perceive light can be changed by eye conditions.

Josef Albers and Johannes Itten key colour theorists.

Colour was originally worked with in pigment / media.
Primary red, blue, yellow mix in the colour wheel to make secondary colours. By mixing primary and secondary colours, tertiary colours are created.

Complementary colours are the chromatic opposites of each other. When these are mixed it creates an absence of colour / grey because the colours cancel out each others wavelengths. By adding a small amount of a complementary colour it dulls the colour, taking some away.

Our eye only sees red, green and blue meaning the eye cannnot physically see yellow even though it is a primary colour. The eye cannot differentiate between a combination of red and green and spectral yellow.

Colour modes
RGB relates to light and is used in screen based colour. It is an additive colour when all the colours are mixed it makes white.
CMYK is used in print and is subtractive as when all the colours are mixed they make black.

Chromatic value = Hue + Tone + Saturation
Hue defines colour and how we describe it
Luminance describes how bright it is and how much light it reflects. Shades of less light are duller.
A Tint is created by adding more white so it becomes lighter.
A tone is created when a shade or tint is added.
Saturation is how bright a colour is and defines how much of vivid pure colour is visable.
Tints, shades and hues push the colour across making it desaturated.
Pantone is a colour matching system.