Terminology
Colour is said to have three dimensions; hue, value and intensity.
Hue refers to the basic name of the colour (red, orange,
yellow etc)
Value, brightness or luminosity is the lightness or darkness of
the colour. This corresponds to the
scale of greys between black and white.
Intensity or chroma refers to the purity, brilliance or
saturation of the colour.
Colour intensity is reduced by adding white or the complimentary
colour.
Tint refers to a lighter than normal value of a colour (pink,
baby blue, aqua etc)
Shade refers to a darker than normal value of a colour (deep
purple, forest green etc)
Tones are colours modified by white or their complimentary
colours.
The Spectrum
When a beam of light passes through a prism it is diffracted or spread
out into the spectrum which we see as the colours of the rainbow.
In the 15th century, Leonardo da Vinci identified four
primary colours: red, yellow, green and blue which are the colours we see most
easily in the rainbow. These colours are sometimes referred to as
psychological primaries because their significance is based on how colour is
perceived rather than on the physical characteristics of light.
These are also the colours traditionally used in school houses or
teams.
In 1666, Sir Isaac Newton named seven spectral zones: red, orange, yellow, green, blue, indigo and
purple each of which have a different, measurable wavelength. The longest wavelength of visible light is red
and the shortest is blue. Newton’s
colour divisions are scientifically based and are still taught today sometimes
by using the mnemonic, “Richard of York gave battle in vain”.
[Newton also connected the different colours or wavelengths to the
seven musical notes of the diatonic scale (C – red; D – orange; E - yellow and
so on) and with the seven “heavenly spheres”, the planets of our solar system
plus the sun and the moon but excluding Earth.]
Although the colours of the spectrum are all part of natural sunlight,
the relative proportions of the colours are variable. Standard white light only exists at
midday: this is when the colours are
seen at their truest and the shadows are black.
In the early morning and late afternoon when the sun is low, blue
frequencies are filtered out by the air and the light is more red and yellow - warm
and glowing and the shadows are blue. At
dawn or dusk, colours are more muted and seem nearer to shades of grey and
objects don’t cast shadows. Moonlight,
reflected sunlight, gives an other-worldly feel to colours which is heightened
by the shadows it produces.
The Colour Wheel
We are taught the three primary colours; red, yellow and blue are used as
starting points when making a colour wheel.
These three colours are generally the colours identified by da Vinci but
ignoring the green. A more accurate
colour wheel can be made by using magenta, yellow and cyan, the colours used in
printing.
Colour accuracy is achieved by careful observation. Only by observing
and getting to know a subject visually, can we start to depict it or
intentionally distort it.
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