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Light colour and colour rendition:
Light colour and colour rendition
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Sunlight
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Sunlight
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Metal-halide lamp
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Metal-halide lamp
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Halogen lamp
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Halogen lamp
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Perceptibility constant
The properties of an object, identifiled
and properly assessed, even under
changing envioronmental conditions,
are know as the perceptibility constant.
Even under various light sources we
always perceive a white cube as being
white. It is only by direct comparison
that we recognise any
difference.
Colour Reproduction Properties
Coloured environments are determined
by sunlight; the continuous spectrum
contains light proportions from every
wavelength range and gives optimum
reproduction of body colours. Lamps,
however, have a discontinuous
spectrum. The light they give out does
not contain all wavelengths and cannot
therefore optimally represent all colours.
Halogen lamps with a continuous
spectrum accentuate red colours.
Metal-halide lamps are available both
with a low colour temperature, i.e. they
accentuate colours in the red spectrum,
as well as with a high colour temperature,
i.e. they throw up colours in the blue-green
spectrum. The colour reproduction
properties of the various lamps are
defined using the Ra index. The higher
its Ra value, the better the lamp's
colour reproduction. Ra = 100 is the
optimum quantity for artificial lighting.
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