What
Symbol
Unit
What does it mean
Luminous
intensity
I
candela
[cd]
Concentration of light emitted in a
specific direction
: I = dF/dΏ
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What
Symbol
Unit
What does it mean
Illuminance
E
lux [lx]
Ratio luminous flux incident on a
surface to the surface itself
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What
Symbol
Unit
What does it mean
Luminance
L
[cd / m2]
Ratio luminous intensity emitted by a
source to the apparent area of the
source
related to
brightness
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Efficienza luminosa di una sorgente è il rapporto tra il flusso luminoso emesso e
la potenza elettrica necessaria per produrlo [lm/W]
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Colore: not only physical
Important: light source, object (surface),
context, observer.....
Obsever: physiological, psycologic aspects,
cultural context, individual experience –
memory...
Perceived colour
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Colour / light
direct (from the source)
reflected
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We look at the light source. Can we measure the colour? How to represent them?
HLS system
Tonalità (Hue)
Saturazione (Saturation)
Luminosità (Lightness)
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CIE L*a*b space
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CIE 1931 colour space
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Chromatic circle.
Michel Eugène Chevreul (to classify colours used in Gobelin tapestries)
1839
Complementary colours are in opposite location on the circle
Complementary colours close to eachother -> brightness enhanced
Very much used by impressionists
Base for Pointilism
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... what if we change the light source?
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What is white light?
Correlated colour temperature (CCT)
Correlated colour Temperature (CCT):
it gives the appearance (cold, warm) of a
white source
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