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Chapter 11 ∣ Color
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• B. The yellow to blue values where positive
b* values (+b*) are yellowish, and negative b*
values (–b*) are bluish.
Metamerism
Metamerism is a phenomenon where two colors
appear the same using one light source but are
different under a different light source. While this
happens regularly in the real world with clothing and
other items, it presents a unique problem for those
in the graphic communications industry. Especially
relevant for web designers and online stores, the
general public wants to know what color an item
is that they are purchasing. Designers can control
the color they use with profiles, and embed that
information into a graphic they upload to the site.
Web browsers are becoming much better at color
accuracy and profile representations. Metamerism
occurs on mobile devices as well, Figure 11-31.
Because of the number of variables that are out
of our control, minimizing metamerism by viewing
color under the proper or expected lighting is
sometimes the best that we can do.
Adaptation
The adjustment eyes make to lighting conditions
is called adaptation. If the eyes experience low
light for some time, the cones and rods grow more
sensitive and light appears brighter. This is dark
adaptation. Just as a photographer increases
exposure time in a dim lighting situation, the dark
adaptation of the eyes increases vision “exposure
time” to raise sensitivity. Your eyes adapt to the
color of light in much the same way. This is called
chromatic adaptation. A good example of this
effect is reading at night using a tungsten lamp that
emits light with a yellow cast. The reader’s eyes
quickly adapt to the yellow color to the point that it is
not even noticeable. If the reader steps outside and
looks in through the window, he or she would clearly
see that the light has a yellow cast.
Adaptation makes it difficult to use your naked
eye to determine such things as the amount of
Goodheart-Willcox Publisher
Figure 11-30. The opponent color theory shows one method of how light is seen and perceived by the brain.
black-white red-green blue-yellow
S = short wavelength M = medium wavelength L = long wavelength
S M L
+
S M L
-
S M L
-
+
Figure 11-31. Metamerism is a color phenomenon in which
colors appear the same in one light and different in another.
Incandescent 5000 K