is the temperature in degrees Kelvin
of a black body (light emitted from a source), heated to produce
a certain color of light. It is a way to describe how blue or red
a light source is. For example, candlelight, which has a color temperature
of around 2000K, is towards the red end of the scale and is considered
a warm(reddish) light source. Sunlight at noon measures out at about
5500K, and is much colder(bluer) than candlelight. If you have ever
observed a campfire you may have noticed that the new flames coming
off of a piece of wood are generally reddish, while the coals deep
in the fire tend to produce a more bluish flame, this happens because
the coals burn at a higher temperature than the fresh burning wood.
Here's a basic
diagram that illustrates color temperature and it's effect on color
images. As you move your mouse cursor over any of the four images
below, the scale to the left will indicate the approximate color
temperature for that scene. These images were photographed with
a digital camera set to record at 5500 Kelvin. If you were to try
this same test with a digital camera set to auto white balance,
your camera would automatically correct the images and try to give
them all a neutral white balance (make them look the same).
Does the color
of the apple and banana change as the color temperature of the light
they are viewed under changes from warm to cold? How would a change
in color temperature effect your ability to assess the color of
a digital inkjet print?
understanding of color temperature is necessary to properly assess
and manage color. It is impossible to manage color under
incorrect lighting conditions, especially prints.
One last item
about color and color perception. There is this nasty little term
called Metamerism that
many of you may have already heard of. You've most likely heard
it mentioned in regards to digital image output, specifically ink
jet printers. Metamerism is a condition, where two samples with
different spectral qualities look the same under different lighting
conditions, IE: color temperatures.
The more important
term to grasp here is metamers. Metamers are two
color samples that look different under different lighting conditions.
For example, you make an inkjet print that looks great (color wise)
under tungsten lamps but when you view it outdoors under daylight
conditions it seems to exhibit an unwanted color cast, view the
print under tungsten lights and it looks fine again. Our eye interprets
the same ink on paper differently dependent on the lighting condition,
namely color temperature.
and metamerism are important terms to understand and consider in
a color managed workflow. The next color topic we are going to explore
is Color Models.
Concepts and Terminology...
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temperature is a way to describe how blue or red
a light source is, it is measured in degrees Kelvin.
is a phenomena where two different colors may match or not
match dependent on the light source they are viewed under.
color temperature of light sources used to evaluate color
should be consistent as it influences our perception of