Apple Motion 5.1.1 - Manual (Page 512)

Chapter 13 Keying 512
In the following image, a clean key is created within the mask by removing the “dirt” left by the
original key.
6 As an optional step, you can nest the originally keyed layer and the holdout matte you just
created inside a dedicated group so you can manipulate the entire subject as a single object.
Apply multiple keys to a single subject
In some instances, it may be difficult to key an entire subject with a single keying filter while
retaining fine details. For example, uneven lighting or background color might mean that the
best settings to key a subject’s hair may not work elsewhere. In such cases, you can use masks to
isolate different parts of a subject, and then apply different keying settings to each area.
Segment a subject into separate keying zones
1 Create a group and place the layer you’re keying in the new group.
2 Duplicate the layer you’re keying until you have a separate duplicate for each part of the image
you want to key separately.
3 Use a mask tool to mask each part of the subject in the duplicate layers.
Note: For more about using the mask tool, see Masks and transparency overview on page 888.
Make sure the duplicate layers overlap, so there are no gaps in the foreground.
Note: You might need to animate the overlapping masks if the foreground subject is moving.
4 Apply the relevant keying filter to the isolated parts of the subject, then adjust each
filter’s settings.
Eventually, you may find you can achieve an optimal key for each part of the subject.
Furthermore, with all duplicates nested in a single group, you can continue to manipulate the
subject as a single object.
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