Primary Color Correction: Tonal Correction Tools - The Art and Technique of Digital Color Correction - page 62

Reset the master curve. In Color Finesse, this is done with the reset
button at the lower right. In Avid, Alt-click on the activated tab to reset.
In many other applications, click on the altered point and hit the delete
key on your keyboard. In Color, click on the small diamond in the upper
lefthand corner of the curve to reset the entire curve or just drag the point
off the graph to remove it. In Color Finesse, right-click a point on the
curve and choose Delete Point from the pulldown menu.
This time, let's place a point on the graph that is just below the
halfway point. I set my point at 120. This point will isolate the mid-
tones and highlights from the corrections we make lower on the curve
( Figure 2.32 ).
Now, click on the same point (63) that you adjusted before and drag
the point up and down as you watch the waveform monitor and video
monitor. You'll notice that the changes to the midtones and highlights are
much less obvious than before. They still move a little bit depending on
what application you use because the point is controlling the curve like a
Bezier curve, so the point is not really a hard and fast cutoff of the correc-
tion. Some applications add much less of a Bezier effect to the curve. Avid
should really require only a single point to isolate the correction. If you
want to, you can add a second point just above the first isolation point.
Fig. 2.32