Chromakey Help for Newbie Please

I’m brand new to editing but am learning. In my first video I made the mistake of not having the green screen evenly lit. This resulted in one small section of the background being a bit lighter. When applying the chromakey filter I can get the subject to look pretty decent, but the background on one edge has the color off enough for me to notice. If I correct that then the subject starts to have the background showing through him, so that isn’t a viable option.

A more advanced editor (who uses another program) suggested I use a mask to essentially select the subject. He said it’s a way of telling the program to use the chromakey in the critical part of the video only and would allow everything else grab the background jpg by default. I cannot find anything though with the mask that seems to do what he’s suggesting. Am I just stuck this time? I have at least learned to ensure the background is uniformly lit in future videos, but ideally I’d like to be able to correct my error this time via the editing process.

Thank you for any recommendations!

Shotcut has a mask filter that you might be able to use to fix the bad spot on your green screen.

I put a flawed green screen on V3 and a text clip on V2. Then applied a mask filter to V3 and positioned it over the bad spot on green screen. Once it was in position I changed the operation from Write on Clear to Subtract and removed the bad spot on the green screen.


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Thank you so very much for the detailed instructions, Sauron. Doing as specified allowed me to cover the bad spot…WOOHOO!!!

For anyone else who might have a similar problem down the road, I found that when I added the chromakey filter after the mask, it overwrote the area I’d just successfully masked resulting in my background colors being off again. However, dragging the chromakey filter above the mask filter allowed the mask work perfectly.

Many thanks again for your help, Sauron!