Primary Color Correction: Tonal Correction Tools - The Art and Technique of Digital Color Correction - page 66

straight lines that are the controls for the Bezier curves of the shadow and
highlight curves.
The curving arcs represent the definition of the shadows, midtones,
and highlights. The tonal ranges are represented by overlapping curves
instead of as strictly defined and delineated areas because if the defini-
tions of the tonal ranges were defined with a sharp cutoff, corrections
to individual tonal ranges would cause sharp, visible transition lines
in the picture at the point where one tonal range was defined from
another.
In Color Finesse, the curves of Luma Range are interactive. The only
way to alter the definition of the midtones is by altering the curve for
highlights and/or shadows. In Symphony, each curve can be radically
altered by setting numerous points on any of the curves. This is a lot of
power, but it can really cause bizarre artifacts in the shot because the
curves can be set to overlap with each other or cut off with abrupt transi-
tions or even leave entire portions of the picture that are not defined by
any tonal range at all!
The value of this control is that it is possible to define very specific
portions of the picture. One example of where this ability would be
useful would be in a shot with a hot window. If the rest of the shot was
Fig. 2.36 In this image, the Luma Ranges are basically unedited. Notice what parts of the grayscale image the Symphony considers
shadows, midtones, and highlights in its default mode.