Primary Color Correction: Tonal Correction Tools - The Art and Technique of Digital Color Correction - page 51

Fig. 2.21 The Symphony Curves controls allow very precise control over specific tonal ranges.
specific tonal ranges. This power of control is a wonderful thing, but like
any kind of power, it can be abused.
DaVinci Resolve, Color, Avid, and Color Finesse give you a curve for
each color channel and a fourth curve for the Master (or Luma). Looking
at the default position of curves makes you wonder why they are called
curves—they're straight!
That's because at their default position, the curves are simple graphs
that indicate that the input level or source level, which is indicated along
the horizontal axis of the graph and is mapped perfectly to the output
level, which is indicated along the vertical axis of the graph.
Imagine if you were to draw numbers from 1 to 100 along the hori-
zontal axis and then do the same along the vertical axis. As you trace
vertically up from the 50 level on the source side, the diagonal line inter-
sects perfectly with the horizontal 50 level on the output side. Similarly,
0 horizontally matches up with 0 vertically and 100 horizontally matches
up with 100 vertically, giving you a perfect diagonal graph.
But if you “curve” that graph—by adding or selecting a point along
the diagonal line and moving it—you remap the input or source levels to
new output levels. For example, to lower the gamma of an image, create
and drag a point in the middle of the curve and pull it down a little. Note
the numerical values at the bottom of the curve. If you pull the center of
Fig. 2.22 The Curves tab in Avid Media Composer 6. Avid color codes the curves so that it's easier to see what will happen when you
move a curve. For example, pulling the green curve down or to the right will make the image more magenta.