Operation Manual

49
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The Tool Chest — Curves
Sampling the Image for Gray Point
The gray point can also be set by direct sampling. Regardless
of the channel currently selected in the channel menu, sam-
pling simultaneously defi nes the gray point for each of the
red, green, and blue chan nels while leaving the gray point for
the master curve unchanged. Grayscale images can not be
sampled for gray point.
To sample the gray point, click the
button. When the cur-
sor is moved over the active image, it will take the shape of an
eyedropper. Move the cursor over the image to fi nd a pixel
to use to set the gray point, keeping an eye on the pixel level
display in the “Information” palette to identify pixels with a
neutral input value (look for pixels that should be a neutral
gray color in the fi nal image). With the cursor over the target
pixel, click the mouse button. The gray point for each of the
component channels will be adjusted to alter color balance
without altering the brightness of the sampled pixel (the
weight assigned to each channel can be selected using the
“Gray point target” options in the “Advanced Color” catego-
ry of the “Preferences” dialog; 101). The image will au-
to mat i cal ly be altered to refl ect the new value for gray point.
Step 5—Editing Curves Directly
Curves can be reshaped to make adjustments to brightness
and contrast in specifi c portions of the tone range.
Adding New Points to the Curve
Move the cursor to the desired location in the curve edit
display and click. A new point will be added at this position
and the curve will automatically be adjusted to pass through
this point. Points can be repositioned by dragging them to
new locations in the curve edit display. Steepening a section
of the curve will enhance contrast in that portion of the tone
range, while changing the curve to map input to higher or
lower output levels will brighten or darken tones in the af-
fected portion of the tone range. The image in the active
window will automatically be adjusted to refl ect changes to
the curve.
Removing Points from the Curve
Points can be removed from the curve by dragging them out
of the curve window.
Resetting the Curves to Linear
The default linear curve for the current channel can be re-
stored by clicking the
button in the “Curves” palette. To
reset all curves to linear, click the
button.
Resizing the Curve Edit Display
Resizing the Curve Edit Display
The Tool Chest can be resized by dragging its borders (Windows) or
by dragging the handle at its lower right corner (Macintosh). The size
of the curves edit display changes with the size of the palette. For in-
creased precision, enlarge the palette when editing curves.