Finalize a key in Final Cut Pro

Quite often your foreground image has objects that you don’t want to appear in the composited output. These could be production items like microphone booms and light stands or the edges of the chroma key backdrop. Additionally, you might need to resize or reposition the foreground object to better fit with the background. As a final step, you can use the color corrector to adjust the foreground so that it matches the look of the background.

Final Cut Pro includes effects that you can use for these purposes.

Use a mask effect to remove unwanted parts of the foreground image

In the Final Cut Pro timeline, move the playhead to the point in the background clip (the clip you want to superimpose the chroma key clip over) where you want the key to start.
In the browser, select the part of the foreground clip (the chroma key clip) you want to key over the background, then choose Edit > Connect to Primary Storyline (or press Q).
For details about connecting clips in this way, see Connect clips in Final Cut Pro.
Select the foreground clip.
In the above example, the light stands need to be removed.
Click the Effects button in the top-right corner of the timeline (or press Command-5).
In the Effects browser, double-click a mask effect to apply it to the selected foreground clip.
Tip: Type “mask” in the Effects browser search field to quickly find the various mask effects. See Intro to masking in Final Cut Pro.
Adjust the edges of the mask to crop out the objects you want to remove.
When adjusting the mask, be sure to leave shadows and other details that can help make the key more realistic later.
Apply the appropriate keyer effect to the foreground clip.
The foreground is composited over the background.

Use Transform to position the foreground image

You can use the Transform effect to reposition a keyed foreground image.

The viewer showing the subject in the foreground clip composited over the background

Select the foreground clip in the Final Cut Pro timeline.
Click the pop-up menu in the lower-left corner of the viewer, choose Transform, and move the image to the position you want.
You can also resize the image.
When you’ve finished repositioning the foreground image, click Done in the viewer.

Helpful?

Final Cut Pro User Guide

Finalize a key in Final Cut Pro

Use a mask effect to remove unwanted parts of the foreground image

Use Transform to position the foreground image