Apple Motion 5.1.1 - Manual (Page 504)

Chapter 13 Keying 504
6 Drag the Erode slider right to soften the matte from the edge inward, while preserving the
original matte outlines as a translucent outer boundary.
Original matte Eroded matte
Animate parameters in the Keyer filter
If necessary, you can animate the parameters of the Keyer filter to account for changes in the
background screen you’re keying. For example, if there’s uneven lighting in the background, and
the camera pans along with a moving subject as she walks from a bright part to a darker part of
the colored background, you can animate the Keyer filter parameters to account for this change.
There are two ways of doing this. You can use the Refine Key controls (Sample Color and Edges)
to sample background colors on multiple frames, or you can set manual keyframes using the
Animation pop-up menu and keyframe controls found in the Filters Inspector.
•
Creating keyframes using the Refine Key controls: When you add a Sample Color box or Edges
control to a clip you’re keying, keyframes corresponding to the Chroma and Luma controls
(in the Color Selection group) are placed at that frame, whether the Record button is enabled
or not. This is the only way of keyframing tolerance while in Scrub Boxes mode, although the
softness of the Chroma and Luma controls can be manually keyframed no matter what mode
you’re in by using the Animation menu of the Filters Inspector.
•
Creating keyframes using the Color Selection controls in Manual mode: In Manual mode, you
can keyframe all aspects of the Chroma and Luma controls using the keyframe controls
or Animation menu. Alternatively, you can use the Record button to keyframe changes to
the Chroma and Luma controls. After you add the first keyframe to the Chroma or Luma
parameters, additional keyframes are added at each frame where you make modifications. For
more information about the Color Selection parameters, see
Keyer filter controls on page 488
and Use the Keyer filter on page 497.
After you’ve added at least one keyframe—by using the Refine Key tools, or by manually
keyframing—adjustments to the Chroma and Luma controls on other frames will generate more
keyframes, whether the Record button is enabled or not.
Tip: To make an adjustment without adding keyframes, use the Jump to Sample buttons (in
Scrub Boxes mode only), or the Next/Previous keyframe buttons to the right of the Chroma
and Luma controls in the Filters Inspector (in Scrub Boxes or Manual modes) to navigate to a
previously keyframed frame.
After you switch from Scrub Boxes mode to Manual mode, work in Manual mode from that
point onward. Switching from Manual mode back to Scrub boxes mode can create unexpected
combinations of additionally sampled and keyframed values that are difficult to control.
Note: Chroma and Luma control keyframes do not appear in the Keyframe Editor. They are only
visible using the keyframe controls at the right of each parameter in the Filters Inspector.
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