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Chroma Key Mask Combination

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Tom Fox
Chroma Key Mask Combination
on Feb 26, 2013 at 5:13:08 pm

Hello all,

I have been lurking here for over 10 years and was completely flabbergasted to find that I had never posted (or indeed signed-up). This must be because CC always has the answer :)

...Until now...

...

I am trying to combine a mask and a chroma,

In the shot, I have the talent in front of a green screen. He is parting his hands to reveal some PIP (picture in picture) video boxes.

I have masked his hands and used the motion tracker to reveal the video PIPs as he pulls his hands apart. So far so good.

the problem occurs when I add a keyer filter both the background and the extra layer that contains the mask and motion tracker.

The mask tracker layer then becomes transparent (quite understandably actually) to reveal the video PIPS below. His hand covers the video but, obviously, the green is transparent.

The layers are as follows:

--- Mask Layer (including copy of hands with a bezier cut-out of some of the green screen behind to mask the pips before the hands reveal
--- PIP layer
---Backround Layer (original video)

I am sure that I am not the first to come accross this issue and I will no doubt be the last. What is the workaround?

Examples (Where black is Alpha):




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Stephen Smith
Re: Chroma Key Mask Combination
on Feb 26, 2013 at 5:24:34 pm

I would make the PIP layers a group and add the mask to that group. Then I would put one layer of the person above that and key the person.

Stephen Smith
Utah Video Productions

Check out my Motion Training DVD

Check out my Vimeo page


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Tom Fox
Re: Chroma Key Mask Combination
on Feb 26, 2013 at 5:42:50 pm

I knew it was that simple....

It was causing my brain to fade...

Thanks Stephen.

It has brought about another problem though. Given that the masks are inverted, and that there is one mask for each hand, one mask will override the other. Would the solution be to (sub) group those two masks or can one put two beziers on the same layer?


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Stephen Smith
Re: Chroma Key Mask Combination
on Feb 26, 2013 at 5:47:22 pm

You can do multiple mask on one group or layer. Once you create your second mask it will add to the current mask, which in your case you don't want. If you go to the Mask Tab in the Inspector you can change the Mask Blend Mode from Add to Subtract and then you will get the results you are after.

Stephen Smith
Utah Video Productions

Check out my Motion Training DVD

Check out my Vimeo page


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