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 adjust to 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.
Create 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. This is the only way to keyframe tolerance while in Scrub Boxes mode, although you can manually keyframe the softness of the Chroma and Luma controls no matter what mode you’re in by using the Animation menu of the Filters Inspector. For more information about keyframe animation, see Animate parameters in the Inspector.
Create 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 (in the transport controls under the Canvas) 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 and Pull a key with the Keyer filter.
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’re only visible using the keyframe controls at the right of each parameter in the Filters Inspector.