Re: Creating a luma matte from subject against black background

Maybe try this:
1. Precomp your footage.
2. Add a white solid and place it under your video.
3. Add curves to your video and crush the blacks, but try avoid making anything in your foreground image too dark.
3. Add Luma Key - Key Out Darker.
4. Play with Luma Key settings until it looks right.
5. Might want to mess with Matte choker effect on top of the key.
6. Add fill and turn it to black.
7. Go back to main comp and use this as a luma matte or reverse luma matte.

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