Using Gmask to isolate a Luma Key area

[mjk12345]

Hi all. I’m relatively new to flame.

I’m trying to do a screen comp on an old TV set with nice rounded edges. The screen is emitting a bright image so I’m using a Keyer Luma to extract a nice matte. All is good and I’m getting a nice matte on the whole screen, however there are some brighter areas around the room and reflections on TV frame that I wanted to mask out.

I wanted to use a Gmask to tell Keyer Luma to focus only on the TV screen area and ignore the room. However, if I plug in a Gmask after Keyer Luma, it generates a white matte in a shape of the GMask but ignores the what the KL did before. I don’t know if I’m making any sense, but what can I do in this scenario? I’m happy with the screen matte created but I want to narrow it down to just the screen.

I thought of using Paint to paint any bleeding onto the room and just leave the screen but it’s a massive pain because there are so many spots I want to exclude.

I could just use Gmask and Mask out the screen and really draw around the edges to preserve the rounded corners but I thought the KL is doing a better job making it more natural with the shape of the screen.

If not GMask, what can I use? Sorry if its such a basic question. Thank You.

[Marcus_M]

In the gmask settings take the colour to 0% and then hit invert. Hope this should do the trick.

[mjk12345]

Thank you. Initially I couldn’t get it to work because I was plugging in a Gmask with a media input not matte input!

[ytf]

Set the mask to 2 Intersect 1 (Inside)

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[joelosis]

@mjk12345

…ding onto the room and just leave the screen but it’s a massive pain because there are so many spots I want to exclude.I could just use Gmask and Mask out the screen and really draw around the edges to preserve the rounded corners but I thought the KL is doing a better job making it more natural with the shape of the screen.If not GMask, what can I use? Sorry if its such a basic question. Thank You.

Also be sure you are using gmask tracer and not the legacy gmask

[BrittCiampa]

@mjk12345

…ding onto the room and just leave the screen but it’s a massive pain because there are so many spots I want to exclude.I could just use Gmask and Mask out the screen and really draw around the edges to preserve the rounded corners but I thought the KL is doing a better job making it more natural with the shape of the screen.If not GMask, what can I use? Sorry if it’s such a basic question. Thank You.

You can use an inverted black mask with the matte plugged into the tracer as mentioned above. But let’s say you have six different areas that you want to luma key and isolate and you don’t want to use six tracers with inverted black masks. In that instance, pull your luma key, pull out a tracer connected to your plate, draw six white masks in that one tracer and then use a comp node set to multiply and plug the luma key into your back and your tracer output into your front and voila.