Colour Theory

What is colour?

Colour has the ability to be perceived through the sense of sight. For example, the only reason we know red is red, is because we have been trained throughout the years to know what colour is what. These colour names are referred to as hues which is the general description or the name that is given to that specific colour. It is a psychological process that will precipitate a physical stimulus, more known as a colour stimulus. There are three different types of photo receptor cells in our retinas of the human eye that are delicate to the rays in which different wavebands are passed through. These are cones. Alongside these, there are other receptors known as rods which is responsible for the sensitivity to brightness. (Keller and Szabó, 2006)

 

There are functions of three factors that we see, that will change the way in which we see colour. Any change of these factors will make us perceive colour in a different way. The three factors which are mentioned in Scene Design and Stage Lighting – page 30 (Pilbrow, 2008) are:

 

  • The colour of light itself
  • The colour of the objectives being observed
  • The ability of the optical sensor i.e. an eye which will distinguish between colours

 

The mass amount of range in a electromagnetic radiation that is visible to the human eye is known as the visible spectrum. Some of the colours that are observable by humans are not within the visible spectrum. These types of colours are made by mixing two or more different wavelengths together. Colours that have only one wavelength are known as a pure colour. The purity of the colour is known as saturation, or less commonly named chroma.

The colours on the spectrum are the same as the ones in the rainbow: Red, Orange, Yellow, Green, Blue; Violet. Because of the fact that light travels in waves, it has both a frequency and wavelength. (Frequency being the number of waves being passed through a given point and wavelength is the distance between two analogous points of waves.

Frequency and Wavelengths

wavelengths

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The visible wavelengths on a electromagnetic spectrum provide the colour and light. Each colour this is made will have its own spectral wavelength. These wavelengths are measured in nanometers. This measures so that 1 nanometer is equivalent to one-billionth of a metre. The visible portion on the spectrum is small section with wavelengths roughly 380 – 750 nanometres. Anything less than 380 nanometres are classed as ultra violets and anything longer than 750 nanometres are classed as infrared.

 

CIE Chromaticity Chart:

.The colour chart shown next to this piece of text, was created by the International Commission on Illumination to stipulate visually relationships that colours have with each other. It quite clearly shows the colour mixing, categorically how a number of  colours are derived from the mixing of the three primary colours.

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(Parker et al., 2008)

The saturated colours are located near the perimeter and become less saturated the further in the chart they go, as they are being mixed with different wavelengths. This will carry on until all the colours mix in the middle which will create white. The curved black line (known as the ‘black body locus) will indicate the exact colour emitted by a light source at any given colour temperature.

 

Colour Interaction:

Colour within light and pigment may be changed through mixing. When different lights of a different colour hit a white surface, the result will conclude in a admixture of all those colours. If the surface itself is coloured, mixing will still take place but the surface of the colour will participate to produce a reflected colour. This is known as colour modification.

 

The colour triangle:

A very good way to illustrate colour mixing, is through the use of a colour triangle. The primary colours are at the three points of the triangle. The colour within the centre should represent all three colours mixed together making white.

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Secondary Hues:

If two of the primary colours are mixed together along the edge of the triangle, it will create a secondary hue. Mixing green and blue together will give you the result of cyan. Red and green will conclude in yellow and red and blue will make magenta. Similar to the primary hues, if the secondary hues are mixed together they will also create white.

Complementary Hues:

Within the triangle, straight across from one of the colours, will be that hues complementary hue. As the triangle indicates, mixing a colour with its complement creates white.

Colour Mixing:

Mixing coloured lighting is a common practise within Theatre. Overlapping the different rays, fills in shadows which create rich and vibrant colours which help enliven a scene.

Primary and secondary colours which are in lighter tints, are generally used for front lighting the performer. However, if using complementary hues, these can create a white hue which is more vibrant than a unfiltered lantern.

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