Inner/Outer Key Effect (Pro Only); Linear Color Key Effect - Adobe AFTER EFFECTS 7.0 Manual

ADOBE AFTER EFFECTS 7.0 465
User Guide
Original (left) and background layer (center) are combined using Extract (right).
See also
"To use the Extract effect" on page 276

Inner/Outer Key effect (Pro only)

The Inner/Outer Key effect isolates a foreground object from its background. Even objects with wispy, intricate, or
undefinable edges can be clipped from their backgrounds with minimal work.
This effect works with 8-bpc and 16-bpc color.
The original masked layer (left) and the background layer (center) are combined using Inner/Outer Key (right).
See also
"To use the Inner/Outer Key effect" on page 277

Linear Color Key effect

The Linear Color Key effect uses RGB, hue, or chroma information to create transparency from a specified key color.
This effect works with 8-bpc and 16-bpc color.
Features such as these eyes (left) that closely match the background (center) can become transparent when using keys; Linear Key keeps them
opaque with the Keep This Color control (right).
See also
"To apply the Linear Color Key effect" on page 271
"To preserve a color after applying Linear Color Key" on page 273