User guide

KeylightThe Foundry
BASIC KEYING
15
Despill Bias
background showing through here. Also, some of the fine hair detail on the
actor, visible in Figure 14, has been eroded in Figure 15.
Despill Bias
Although the foreground is despilled automatically, you may find the need
to pull out a little more of the screen colour after picking from the image.
You can do this with the Despill Bias control. Just increase the parameter
until the blue disappears. However, if you increase too much the foreground
will become transparent.
There are ways to fix that and these are covered in the next chapter. See
“Biasing” on page 18.
Figure 14. Screen Strength = 105 giving a
good Screen Matte.
Figure 15. Screen Strength = 150
giving background show through and
over eroded edges.
Figure 16. Exaggerated blue spill. Figure 17. Despill Bias used to remove the
blue spill.