Apple Motion 3 - Manual (Page 1099)

Chapter 12 Using Shapes and Masks 1099
Feathering Masks
One of the easiest ways to adjust a mask is to feather its edges. Feathering a mask by a
few pixels can make the masked object blend more seamlessly with a background.
Feathering a mask by larger amounts allows you to create progressively softer edges
for a variety of design purposes.
You can feather mask edges either outward or inward. The direction in which you
feather a mask is dictated by the subject you’re masking. When rotoscoping a subject, a
combination of masks using both inward and outward feathered masks may be
necessary for the best results.
To feather the edge of a mask:
1 Select a mask.
2 Open the Mask tab in the Inspector.
3 Do one of the following:
 Drag the Feather value slider to the right for a positive value to feather the mask
outward.
 Drag the Feather value slider to the left for a negative value to feather the mask
inward.
Feathered in (color channel) Feathered in (alpha channel)
Feathered out (color channel) Feathered out (alpha channel)