Adobe After Effects CS3 - Manual (Page 456)

AFTER EFFECTS CS3
User Guide
451
Original (top left) shows areas of unwanted transparency after using Color Key (bottom left) that are removed with Matte Choker (bottom
right).
See also
“Keying overview and tips” on page 268
“Close a hole in a matte” on page 271
Simple Choker effect
The Simple Choker effect shrinks or expands the edges of a matte in small increments to create a cleaner matte. The
Final Output view displays the image with the effect applied, and the Matte view provides a black-and-white view of
the image with black areas indicating transparency and white areas indicating opacity. Choke Matte sets the amount
of choke. Negative values spread the matte; positive values choke it.
This effect works with 8-bpc and 16-bpc color.
Original (top left) contains unwanted edges after keying (bottom left) that are removed with Simple Choker (bottom right).
See also
“Keying overview and tips” on page 268