Game Development Reference
The Color Key Effect
The Color Key effect is probably the polar opposite of the Color
Difference Key effect. The Color Key effect is extremely simple
and straightforward, but the results are usually well . . . bad. Even
with really clean footage that has subjects with solid edges, the
Color Key effect has a tough time.
I'm going to import the Artbeats video clip UM230.mov from
the Artbeats folder in the Media folder of the exercise fi les. This is
professionally shot footage of autumn leaves falling. Low noise,
good lighting, perfect green screen—the whole bit (Fig. 10.9).
Figure 10.9 The Artbeats
footage of leaves falling.
You would think that this would be easy footage to key, right?
Well, not for the Color Key effect. Let's see how the results turn
out. Click the eyedropper next to the Key Color swatch, and click
on the green screen in the footage in the Composition panel.
Only a handful of pixels are removed, so increase the Color
Tolerance value to remove more of the green screen background.
Chances are, the results will look awful no matter how much you
play with this setting. You can use Edge Feather to soften the
edges. You can also use Edge Thin to fi x the edges, but be care-
ful here. Increasing the value just a little bit will eat away at the
edges of the subject. Taking this to a negative value will expand
the edges of the subject. It's best to use this property sparingly, if
Overall it's almost impossible to pull a good key with this effect.
Even if you manage to get a frame looking good, usually after pre-
viewing the video, the edges of the subject will “dance” around,
looking jittery. I would only use this effect if a client was stand-
ing over my shoulder, or in some other instance, where I needed