Apple Shake 4 - Manual (Page 710)

710 Chapter 24 Keying
hiVal
Any pixel above this value (as calculated by its luminance) turns white.
loSmooth
A roll-off factor to provide a smooth drop-off.
hiSmooth
A roll-off factor to provide a smooth drop-off.
matteMult
Toggle to premultiply the RGB channels by the pulled mask.
• 0 = no premultiply
• 1 = premultiply
Primatte (Plug-in)
The Primatte plug-in is the latest update of Photron’s Primatte keying software. The
Shake Primatte node allows you to scrub across an image to determine matte areas in
order to pull a key (or alpha channel) for a composite. The plug-in also works on the
RGB channels to suppress spill (the leaking of blue or green color onto the foreground
objects).
Note that Shake scripts pass special data to the Primatte plug-in. This data is encoded,
which means that Primatte must be set up using the graphical interface.
To learn how to maximize the effectiveness of this node by combining it with other
functions, see Tutorial 6, “Using Primatte,” in the Shake 4 Tutorials, as well as this
manual’s section on “
Blue and Green Spill Suppression ” on page 687.
Supplying the Background Image
Although you can output Primatte with a premultiplied foreground with no
background image, you should supply a background input if possible, as Primatte still
factors in some of this information. If you do not supply this image, black ringing
appears around the edges. If this is impractical, toggle the replaceMode parameter to
use color and supply an appropriate Replace Color.