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The Curves 1 property page controls
the appearance of the curves, and display of curve data:
- Grid controls the number of grid lines that divide the curve
graph area as a percentage. For example, 25% denotes four squares.
- Squares allows you to specify any number of squares that you
wish.
- Labels controls whether or not the curve axes are labeled or
not.
- Diagonal specifies that a diagonal line be drawn between the
two corners of the curve.
- Histogram Show specifies that a histogram be displayed within
the curve area.
- Use exact values specifies that every pixel be counted in determining
the histogram, instead of a subset of pixels.
- Color Frames specifies that the frame of color channels reflect
that color. Otherwise, the frames are gray.
- Black on Left specifies that the left and bottom edges of the
curve correspond to black. This option is saved separately for each
color mode so, for example, CMYK may be specified as having black on
the right, and RGB may have black on the left.
- Master Channel specifies that an RGB master curve be displayed
for RGB mode, and a wgCMYK curve be displayed for wgCMYK mode. This
option is saved separately for each color mode.
- Square Graph specifies that graphs always be displayed square,
even if this uses less available area for each curve.
- Top Left #'s specifies that the editable numeric fields associated
with each curve begin life in the upper left corner, instead of the
lower right.
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Figure
1. The "Curves 1" settings contains options that generally apply
to the appearnce of the curves. |
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The Curves 2 property page contains
mainly options that affect curve preview behavior and resulting image
color values.
- Units settings control the display of values
in the sample palette, the representation of newly saved pins, and the
export of curve and color values via the clipboard.
Certain channels are not affected at all by the units setting. These
are the a and b channels of Lab, which always range from -128 to 127,
and the H and S channels of HSB, which are always in degrees and percent
saturation, respectively.
Units are specified separately for each color space.
- Auto duplicates Photoshop's behavior. If curve display
specifies that black is on the left, curve display units from 0
to 255, with zero representing black, and 255 representing maximum
brightness, respectively. If black is on the right, units are in
percent ink values, with 0% and 100% representing white and black,
respectively.
- 0 (Black) - 255 (White) means that zero represents black,
and 255 represents the maximum brightness value for the channel
value of each curve
- 0% (White) - 100% (Black) means that "ink" units
are used, with 0 representing white, or no ink, and 100 representing
black, or the maximum amount of ink.
- CurveGuard Enable prevents any curve from being modified to
have a minimum or maximum slop outside the specified bounds.
- Maximum and Minimum Slope control the allowable steepness of
modified curves.
- Corner Fill modifies curve behavior
outside of the curve's end points as shown in figures 3 and 4. Corner
fill improves the behavior of CMYK black points, and is also useful
for bringing out shadow and highlight detail since it approximates the
"lizard tail"
curve shape..
- Continuous Preview specifies that image colors will change
as you modify a curve, instead of waiting for the mouse button to be
released. Continuous preview is normally disabled only on slow systems.
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Figure
2. "The Curves 2" settings control curve behavior. |
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Figure
3. A curve shown with the corner fill option enabled. The cursor points
to a curve endpoint.
The line connecting the endpoint to the white corner of the curve is known
as
"corner fill".
Figure
4. The same curve as figure 3,
shown with corner fill disabled.
This behavior is the same as Photoshop's
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located at the top of both the curve and image window. Many of the options in
the Curve Options dialog may also be changed via menu commands, by right clicking
on a curve, or by clicking on the circular menu button 
in the upper right corner of the curves dialog.