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The Tool Chest — Curves

White Point and Black Point Output Levels

Once the input levels for the black and white points have

been determined, output levels can be altered to reﬂ ect 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.

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 ef-

fects of the change will be reﬂ ected in the active image.

Black-point

output slider

White-point

output slider

Output Levels

In some cases, it is best if the darkest and lightest points of the image

are not printed or displayed as saturated black or white, even when the

colors in the original represent a true black or true white. For example:

• Making blacks less saturated can reduce the amount of ink consumed

• Making whites less saturated can prevent undesirable lines from ap-

pearing when a true white is printed in ink (for example, when white is

printed on a colored background)

Default Output Values

The default output levels for white point and black point can be set in

the “Advanced Color” category of the “Preferences” dialog ( 101).