How to remove a "chroma key" hole in a person shape

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dejudicibus

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How to remove a "chroma key" hole in a person shape

PostSat Oct 16, 2021 3:32 pm

I have a clip with a person in front of a green screen. I removed the green in color correction by using the 3D qualifier but a small glare on his glasses creates a hole in the person shape. So I have to remove that hole too, by telling DaVinci Resolve not to consider that small portion of the screen for alpha output. But how? I tried with masks but with no success. Any idea?
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Glenn Sakatch

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Re: How to remove a "chroma key" hole in a person shape

PostSat Oct 16, 2021 3:50 pm

The technique will depend a bit on how you are pulling your key.
An easy way would be to bring your source node back into play after your key, and use a mask to only see the portion of the shot you need to fix.

Inverted masks during the actual key would be another way of achieving this.
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Marc Wielage

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Re: How to remove a "chroma key" hole in a person shape

PostMon Oct 18, 2021 12:38 am

Yes, draw a window INSIDE the person, then use that as a mask (invert the window) so it only does the chromakey OUTSIDE the mask. I have to use garbage mattes like this a lot of times, particularly in shots that need relighting: one person is "lit" with a window, then another crosses in front of them. You have to use another tracked window to avoid having the second person get affected by the first person's correction.

This is the essence of dealing with Occluded Objects, and that and garbage mattes go hand in hand. Very important concept in VFX and color. Basically, it boils down to "only have the effect change what I want, not what I don't want."
marc wielage, csi • VP/color & workflow • chroma | hollywood

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