Apple Color 1.0 - Manual (Page 219)

Chapter 10 Secondaries 219
Note: You can manually set the key blur to even higher values by typing them directly
into the Key Blur field.
One of the nice things about keying for color correction is that, unlike when keying to
create visual effects, you don’t always have to create keyed mattes with perfect edges
or completely solid interiors. Oftentimes an otherwise mediocre key will work perfectly
well, especially when the adjustment is subtle, so long as the effect doesn’t call
attention to itself.
Also, it’s important to bear in mind that sometimes a hole in the keyed matte you’ve
been worrying about might actually correspond to a shadow in the subject you’re
isolating that you don’t actually want to be part of the correction.
Previews Tab
The Previews tab is a two-part display that helps to guide your adjustments while you
use the HSL qualifiers and the vignette controls described in this chapter. Two reduced
resolution images show you different views of the operation you’re performing.
No key blur With key blur
Check Your Secondary Keys During Playback
It’s a good idea to double-check to see how the secondary keys you pull look during
playback. Sometimes a secondary operation that looked perfectly good while you
were making the correction exhibits flickering at the edge or “chatter” that is the
result of noise, or of including a range of marginal values that are just at the edge of
the selected range (this happens frequently for “hard-to-key” features in an image). In
these cases, additional adjustments may be necessary to eliminate the problem.
Also, secondary keys that work well in one part of a shot may not work so well a
couple of seconds later if the lighting changes. Before moving on, it’s always a good
idea to see how a secondary operation looks over the entire duration of a shot.