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White Point and Black Point Output Levels
Once you have set the input level for the black point and white
point, output levels can be altered to reflect the actual shade of
the darkest and brightest pixels in the image. If the darkest
shade in the image represents a true black, for example, the
output level for the black point can be left at zero. If, however,
darkest shade present in the image is a lighter color, the output
level for the black point can be raised to achieve more natural
coloration.
The output levels for the white point and black point are set
using the white-point and black-point output sliders on the left
side of the curve edit display.
White-point
output
slider
Black-point
output
slider
Reference: The Tool Chest
To set the output level, click the slider once to activate it, then
drag it up or down until you have found the desired output level
(the output level can also be set by entering a value directly in
the text box to the left of the slider). The effects of the change
will be reflected in the active image.
It is sometimes the case that the darkest and lightest points of
the image should not be displayed or printed as a saturated
black or white, even where the colors in the original image rep-
resent a true black or true white. The reasons for this are
varied, but include:
• The need to reduce the amount of ink consumed by making
blacks less saturated
• The need to prevent an undesirable line from appearing when
a true white is printed using ink (for example, when printing
whites on a colored background)
• The need to prevent distortion on monitor or television sets
caused by very strong or very weak signals at the edges of
the screen
Pg. For more information on:
134 Setting default output values for the eyedropper tools
71
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