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Light and color Visual system
Light
is energy in the form of electromagnetic radiation
in the range entities of wavelength between 380nm and 770nm, which is
what our visual system can perceive. Colour is the interpretation
that makes our visual system of the structural composition of the
detected light by the eye. Every illuminated surface absorbs all or
part of the electromagnetic radiation and reflects the rest. The
colour which we perceive depends on the amount of light that is
emitted, reflected, transmitted and absorbed for each wavelength in
the visible spectrum. The human eye only perceives colour when light
is abundant. With little light we can see black and white. White
colour is the result of the combination of all the colours, while
black is the absence of light.
A
white light can be
separated in all the colours (spectrum) by a prism. In nature this
separation occurs in a rainbow. The temperature of the colour is a
parameter which is used to indicate the tone of white light for the
comparison of a black body at that temperature. Meanwhile the
reproductive chromatic index indicates the capacity of a light source
for reproducing colours of illuminated objects.
 
Colour
is artificially generated by the combination of the primary
wavelengths: red, green and blue, keeping in mind the characteristics
of our visual system. Colours are classified in groups warm (yellows
and reds) and cold (greens and blues). The CIE (International
Commission of Illumination) has defined as a standard of
identification the chromatic colour diagram CIE, where each colour is
represented by the coordinates X and Y. For non light emitters of
colour it is also possible to generate by absorption, emission or
addition of wavelengths.
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Colours
produce some physiological and psychological effects over people such
as:
Sense
of warmth: warm colours (from red to yellowish green). They are
dynamic, exciting colours that produce a sensation of closeness.
Sense
of cold: cold colours (from green to blue). Colours that calm and
rest, producing a distancing feeling.
Purity
or saturation of colour: the clear colours animate and give the
sensation of lightness, while darker colours depress and give a
slowing feeling.
Harmony:
is produced when two or more colours are mixed with a nice effect.
Recent
studies have demonstrated that the colour of Light produces
alteration in the cardiac rhythm and facilitates the conciliation of
dreams.
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