Primary Color Correction: Tonal Correction Tools - The Art and Technique of Digital Color Correction - page 63

Try 130 or 140. This will limit the amount that the Bezier curve affects the
curve about the higher mark. Now, move the lower (shadow) point again
while watching the waveform monitor. Also watch the video monitor;
you can see that the shadows are being deepened, while the highlights
and most of the midtones don't move at all.
If you bring the shadows down far enough, you will see that you start
to crush the middle chip that is at 0IRE. The crushing or clipping is indi-
cated by the waveform trace starting to flatten out. If you want to protect
the deepest blacks from clipping, you could also place a point on the curve
that is very low. This will protect the detail in the deep blacks while allow-
ing you to pull the rest of your shadows deeper. I placed my point at 16.
Then, as I brought my shadow point (input 67) down to an output of 51,
the darkest black did not clip ( Figure 2.33 ) .
To practice this some more, continue this same correction without
resetting it and try to get the brightest chip on the right side (the chart was
lit a little brighter on the right side) to 100IRE and the next three chips to
land at 80, 70, and 60.
The key to this exercise is figuring out what point on the master curve
corresponds to the luminance value of the chip as it is viewed in the wave-
form monitor. This is a very valuable skill to have. You should be able to

W A R N I N G
A reminder about moving
points that are too close
together: There are only
so many levels of gray
between points, and if you
stretch them too far or
condense them too closely,
your image will fall apart.
By “fall apart,” I mean that
it will either exhibit a lot
of noise or posterization or
banding. These faults in the
picture will be much more
noticeable than any errors
that you're trying to cor-
rect, so try to avoid taking
the image beyond where
it can go.

Fig. 2.33