This sub-menu adds control points to existing curve positions, effectively
re-enforcing or Pinning the current curve position. This is an advanced
feature that facilitates modification of one part of the curve without changing
the pinned portion of the curve. For example, you might pin one half
of a curve in place before changing data values in the other half.
This sub-menu controls the behavior and display characteristics of the curve.
CurveGuard,
enables the Curvemeister CurveGuard
option. If a check mark appears next to this menu item, you may not drag
a control point is so as to create a negative sloping curve. If CurveGuard
is disabled, Curvemeister CurveAlert
will use a red color to indicate a possible problem. Power users:
CurveGuard will behave appropriately if the curve are inverted before the
a middle control point is added.
Black
on Left, when checked, specifies that the left edge of the graph corresponds
to a darker color than the right edge. By convention, the RGB, HSB, and
Lab color spaces use black on the left, corresponding to increasing brightness
value from left to right. CMYK and wgCMYK by convention use black on the
right, indicating increasing ink density from left to right.
RGB
Master Curve specifies that a global brightness curve be displayed for
the color space, in this case the RGB color space. This menu item is only
enabled for the RGB and wg-CMYK color spaces. This option should be used
sparingly because it will create color casts. It is useful for setting overall
brightness, and for setting the black and white thresholds for images that
lack a suitable neutral shadow or highlight point.
Histogram 
This sub-menu controls the histogram that may be optionally displayed
in the curve area.
Show
Histogram determines whether the histogram, which shows a graphic
summary of the pixel values in your image, is displayed.
Precise
(Slow) determines whether the histogram is calculated from a subset
of image data, or by scanning every pixel of the image. For many purposes,
the Precise option is not necessary, and there is a substantial
startup delay for large images if this option is enabled.
Axis
Label specifies that the curve axes will be labeled appropriately. Some
or all of the labels may disappear if there is no room for them.
Grid Lines
This sub-menu specifies the number of grid lines that divide the graph
area.
None Displays no curve grid marks at all.
10% and 25% Displays 10, or 4 grid divisions,
respectively. These grid lines are for appearance only, and are used by
the Pin Grid commands.
11 Divisions Displays 11 divisions corresponding to the photographic
Zone System used in photography, and popularized by Ansel Adams.
Diagonal
Reference Line specifies that a diagonal reference line be drawn on
the graph. This line represents curve points that map input values to the
same output value. It is useful for restoring curve sections that have inadvertently
strayed as a result of adjustments elsewhere.
Color
Frames specifies that the border of the curve is to be colored to indicate
the image data controlled by that curve. Although it is informative to use
color to indicate the type of curve, color can also impair your ability
to perceive color in the actual image. For this reason, many people prefer
to minimize the color on the screen that is not part of the image.
Continuous
Update, when checked, specifies that the preview image is always
changed when the curve is changed, rather than after the mouse button has
been released. This option may improve the user interface performance on
old systems with CPU's slower than 400 MHz..
