About Colours; Rgb And Cmyk Models - Minolta CF5001 User Manual

About Colours

RGB and CMYK Models

Have you ever wondered why the world surrounding us appears coloured to our eyes?
Light is electromagnetic waves with wavelengths between about 380 - 780 nm, also
called visible rays. The wavelengths of visible rays can be separated into the rainbow
colours violet, indigo, blue, green, yellow, orange, and red, from the shortest
wavelength in order. When all the wavelengths of the visible rays strike your eye at
the same time, white colour is perceived. We see the objects in colour because they
reflect or transmit visible light of different wavelengths or frequencies.
Prism
Slit
White light
The colours separated from visible light are called primary colours. Primary colours
cannot be produced from other colours. These colours, however, can be combined to
make up any other colour (colour mixture).
The colour mixture provides two different types, three primary colours of light and
three primary colours of pigment. The three primary colours of light are called
additive colour mixture, and the more colours are added, the brighter it will be. Mixing
red (R), green (G), and blue (B) coloured lights, various colours can be created.
The three primary colours of pigment are called subtractive colour mixture, and the
more colours are added, the darker it will be. Various colours can be created by mixing
cyan (C), magenta (M), and yellow (Y) pigments (such as ink or toner), however, black
(K) is actually used as the fourth colour in addition to the three primary pigments.
Three primary colors of light
7-2
(nm)
780
750
700
650
600
550
500
450
400
380
Visible rays Electromagnetic wave
Three primary colors of pigment
(m)
10 8
10 6
10 4
10 2
1
10 -2
Light
10 -4
10 -6
Reflection
10 -8
10 -10
10 -12
10 -14
Colour