Apple Shake 4 Tutorials - Manual (Page 190)

190 Chapter 6 Using Primatte
By using the foreground and background operators, you have assigned pixels to either
zone 1 or 4. Picking any of the eight operators assigns color to a different zone. The
following image is a chart of the operator/zone assignments.
This illustration demonstrates (roughly) how each operator dimples the surface of the
zones through the use of successive color picks. You may have seen implementations
of Primatte in other software using a real 3D representation of the color space using
polygons. While cool, only about three people on the planet seem to understand it.
Managing Operators
One swell thing about Shake’s implementation of Primatte is that you can review,
modify, or delete previous operators at any time. You do not have to start over from
scratch if you are not happy with the key. Use the parameters shown in the following
illustration to review, modify, or delete previous operators.