Apple Color 1.5 - Manual (Page 237)

To make curves sharper, move their control points closer together. To make curves more
gentle, move the control points farther away from one another.
The following procedures describe how to create, remove, and adjust the control points
that edit curves controls.
To add control points to a curve
µ
Click anywhere on the curve itself.
To adjust a control point
µ
Drag it anywhere within the curve control area.
To remove control points from a curve
µ
Drag a point up or down until it's outside the curve control area.
To remove all control points from a curve
µ
Click the reset button (at the upper-left side of each curve graph) for the curve from which
you want to clear control points.
Using Curves to Adjust Contrast
One of the most easily understood ways of using curves is to adjust contrast with the
Luma curve. The Luma curve actually performs a simultaneous adjustment to the red,
green, and blue channels of the image (as you can see if you take a look at the Parade
scope while making Luma curve adjustments), so the overall effect is to adjust the lightness
of the image.
Note: Adjustments made to the Luma curve may affect its saturation. Raising luma by a
significant amount can reduce its saturation.
237 Chapter 9 The Primary In Room