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Graphic Communications
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light needed in certain photographic situations.
Adaptation is also part of the reason viewing
booths are used when proofing printed materials.
A viewing booth has color-balanced lighting
(5000 K illumination), so anyone viewing the same
printed materials sees them under identical lighting
conditions. The light temperature used in a viewing
booth appears clear and color-balanced, and is
ideal for making color comparisons, Figure 11-32.
Cones and rods in the eye adapt at different
rates. Cone adaptation occurs in about seven
minutes, while rod adaptation continues for an
hour or more. Decreased light and increased visual
sensitivity also reduce the ability to make out fine
detail.
Adjacency
Adjacency is a change in color perception that y
is caused by colors adjacent to or surrounding a
subject, Figure 11-33. If you place the same color
against different background colors, the color
appears different in each scenario. For example,
a color looks brighter if the surroundings are dark,
but the same color looks darker if surrounded by a
lighter color. The same color surrounded by different
colors appears different. Additionally, a color looks
more saturated if surrounded by a complementary
color. This color-vision effect is called chromatic
induction or simultaneous contrast.
Color Constancy
Color constancy is the tendency to perceive y
the color of an object to be the constant, even
when environmental conditions (such as lighting)
are changed. Skin tones are also commonly
misperceived. When viewing the printed image of
a person, for example, his or her skin color may
appear correct due to the color maintained in the
viewer’s memory. The actual difference in color
is apparent when the person is compared to the
printed image.
Color Viewing Variables
Although the human vision system is both highly
sensitive and accurate, it is also very subjective.
Visual perception varies among individuals for many
reasons and can even be affected by changes in
emotional and physical states.
Color Blindness
The ability to see in color is not inherent to
all animals. Although some birds, fish, reptiles,
and insects have highly-developed color vision
systems, it is almost certain that very few mammals
below the primates possess color vision. Among
Goodheart-Willcox Publisher
Figure 11-33. When a color is viewed against a light
background, it appears darker. When the same color is viewed
against a dark background, it appears lighter. Surrounding a
color with different colors makes it appear different.
Photo courtesy of GretagMacbeth, New Windsor, NY
Figure 11-32. Standardized viewing conditions are
necessary to properly evaluate color reproduction. This
viewing booth emits 5000 K illumination.
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