Apple Shake 4 - Manual (Page 703)

Chapter 24 Keying 703
ChromaKey
The ChromaKey node examines the HSV values of an image and pulls a matte based
upon the parameters. In the interface, you can scrub a color in the Viewer. However,
disable the matteMult parameter before you scrub. The hue, saturation, and value of an
image each has a set of parameters to describe the exact HSV values you are keying, as
a range from that midpoint, a falloff value, and a sharpness value to describe the falloff
curve. This is illustrated in the following image:
The ChromaKey node is not Shake’s strongest feature. It is recommended to use Color–
ColorReplace; select your bluescreen color; choose your destination color (any other
color); then enable affectAlpha.
A typical application is bluescreen or greenscreen removal. You can stack multiple
ChromaKey nodes to extract different ranges. With the arithmetic parameter, you can
choose to add to, subtract from, or replace the current mask.
Parameters
This node displays the following controls in the Parameters tab:
HSVColor
Picks the center value to be pulled on hue, saturation, and value.
hueRange
Plus and minus from the hue specified by the HSVColor parameter.
hueFalloff
Describes the falloff range from hueRange that is picked, with the values ramping
down.
hueSharpness
Describes the falloff curve from hueRange to hueFalloff.
• 0 = linear drop-off
• 1 = smooth drop-off
satRange
Plus and minus from the saturation specified by the HSVColor parameter.
satFalloff
Describes the falloff range from satRange that is picked, with the values ramping down.