312 A DICTIONARY OF COLOUR
a prasinous
The colour of the leaves of leeks or onions.
n Pre-Raphaelite colours
The natural colours used by those painters, called Pre-Raphaelites, who adopted
the style of artists before the time of Raphael (1483-1520).
n primary colours
Originally, the colours of the spectrum: red, orange, yellow, green, blue, indigo,
violet. As regards surface colour, pigments and paints the term now usually
refers to the three colours red, blue and yellow (also known as elementary colours
and fundamental colours) from which all other colours can, in theory, be derived.
Mixing all three primary colours produces black by the subtractive process.
Primary colours are colours which cannot be created by mixing any other colours.
For digital images and coloured light (for example, on a monitor or television)
the primary colours are red, green and blue (or violet-blue) (RGB) which, when
mixed, make white by the additive process. See additive colour and digital
colour. The primary colours in printing are cyan, magenta, yellow and black
(CMYK) and in colour photography, cyan, magenta and yellow. There have been
other triads of primary colours – such as black, white and red – which have had
widespread appeal over the ages. Also Aristotle’s puniceus, viridis and purpureus
– the exact hues of which are unknown. See also secondary colours, subtractive
primary colours and additive primary colours.
n primary visual cortex
That part of the occipital lobe at the rear of the brain (referred to as V1) which
receives signals from the eye via the optic nerve and dispatches them to other
parts of the brain for processing including V2 and V4 which process colour
information. The Nobel prizewinner Professor Roger Sperry determined in the
1960’s that, of the two hemisphere’s of the human brain, it is the right hemisphere
which dominates in relation to the assimilation of colour. The left hemisphere is
dominant as regards other disciplines such as language, maths and logic.
n primer
Any of the many various substances of different colours applied to a surface and
serving as a base in preparation for receiving paint. See gesso, imprimatura,
pink primer, red lead, and size.
c primrose
Pale-yellow. Also ‘primrose yellow’.