Apple Motion 3 - Manual (Page 1100)

1100 Chapter 12 Using Shapes and Masks
Applying Filters to Masks
As with shapes, you can apply filters to masks, which remain editable even after the
fact. Although uses for this technique might not be immediately obvious, it’s actually
an extremely powerful way to further manipulate the alpha channel created by one or
more masks.
For example, you could apply the Crystallize filter to a mask to stylize its edges. This
results in jagged edges that resemble facets of crystal around the edges.
When applying filters to masks, it’s useful to bear in mind that masks are just grayscale
images. In the example above, the Crystallize filter creates patterns in the grayscale
mask image, which results in a rippled translucent pattern.
To apply a filter to a mask, do one of the following:
m Drag a filter from the Library directly onto a mask in the Layers tab or Timeline.
m Select a mask in the Layers tab or Timeline layers list, then choose a filter from the Add
Filter pop-up menu in the Toolbar.
The filter appears nested underneath the mask layer to which it’s applied.
Original mask (color channel) Original mask (alpha channel)
Crystallize filter applied to alpha channel
(color channel) Crystallize filter applied to alpha channel
(alpha channel)