Inverting Magnetic masks (plural) in FCP

Question

I have a clip (inside of car) and I want to see a sunset through windows (plural).

That part works fine.

However there is movement in front of some windows, seats folding etc.

So I have had to split it into 6 masks that will allow sunset to be seen behind.

My problem seems to be how to invert a single mask without invert all the others including top track.

Is there a way to determine if a mask is positive or negative if you know what I mean.

I presume I want the top track to be positive with all the masks in the windows negative so I can see the sunset.

Hopefully someone can help!

iMac 24″, macOS 15.6

Posted on Nov 5, 2025 9:17 PM

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Answer 1

Top-ranking reply

Level 9

72,750 points

Once you have the first mask set, you click the little icon with an ellipse inside a rectangle and choose Add Magnetic Mask, adjust, etc.

Then instead of selecting "Invert Masks", which invert everything, you can change the secondary masks from "Add" to "Subtract":

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Answer 2

Thanks for your help Luis.

My guess worked out ok, Mask whole image then subtract masks from that.

All done now. I don't think there was a way to use previously created masks so at least I had practice doing them again.

Thanks again

Phil

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Answer 3

Would it be possible to post some screenshots illustrating what you are seeing?

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Answer 4

Didn't quite work out.

Some of the masks (to remove) go right to edge of image so I guess I may have to initially Mask whole of image

then Subtract the individual masks from that.

Is there a way to use the Masks I have already created.

It doesn't seem to give me an option, Add, Subtract or Intersect until I have created a new (blank) mask.

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Answer 5

Thanks Luis, I shall give that a try.

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