Operation Manual

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The Tool Chest — Curves
White-Point and Black-Point Sliders
The white-point and black-point sliders can be used to match
the white and black points to the his to gram displayed in the
curve edit display. While these sliders can be used to edit
curves for any channel, the best results are usually obtained
when they are used to modify the master curve.
To edit the white point or black point, click the correspond-
ing slider once to activate it, then drag it to the right or left (a
value can also be entered directly in the text box underneath
the slider). Matching the black-point slider with the low-
est input value displayed in the histogram will set the mini-
mum output value for the selected channel to the darkest
pixel actually present in the image, steepening the curve and
enhancing contrast without sacrifi cing detail in shad ows.
Similarly, matching the white-point slider with the highest
input value displayed in the histogram will set the maximum
output value for the selected channel to the brightest pixel
present in the image, enhancing contrast without loss of de-
tail in highlights. Any changes are applied instantly to the
active image.
Black-point
slider
White-point
slider
Black-point
input value
White-point
input value