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Keylight inside mask – need help
I’m using Keylight on clip that has a green screen – think projector screen – in which an instructor walks in front. This screen is in a wide shot, so heads of the students are also in the screen and the screen is within the context of a room. There is a fair amount of green spill reflected on the foreground images so I’ve been unable to get a clean key with the Keylight controls – I’m trying not to color correct.
So I’m trying to create an Inside Mask for Keylight by creating a high contrast matte from a duplication of the clip. I turned ithis to a pre-comp and assigned this clip as a matte for the original clip using Set Matte. I then apply Keylight to the original clip but Keylight doesn’t find it.
So, my big question is “How can I use a high contrast matte as an Inside Mask in Keylight?”
I’ve been all over this forum and can’t find an answer.
(the footage in question is DVCPro HD 60p)
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7 Replies
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Aharon uses Auto Trace to create a super-tight junk mask, and expands it with a Choker, would that help?
https://library.creativecow.net/articles/rabinowitz_aharon/junk_mattes.php
If not, I probably don’t understand what you’re trying to do.
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I looked at the auto trace tutorial, and not sure it would work. It has an actor on a green screen which fills the frame.
My scenario is a class room with a projection screen which instead of projecting the instuctional material and other footage while we shot we decided to cover it with green paper and then in post replace the green with the appropriate information for the course. So its more like an object in our shot that has a green surface to be modified in post. Think of a box in a larger scene with the face of the box green, actors moving in front of the box, but we need to change the face of the box as the scene progresses – and I don’t want to rotoscope a mask – it’s a four minute clip.
Therefore I was hoping Keylight would do the trick with an Inside Mask based on a high constrast matte created from a duplication of the clip.
Does this clarify?
Thanks.
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i think i get it… i also think i understand the problem with keylight… keylight is looking for a mask (like the vector mask you add to a layer) not the matte that you have created, but that’s no a big deal.
you can use the matte that you have as a track matte for the footage. just place the matte above the footage. then from the ‘modes’ panel (of modes/swithces) set the footage layer to use the lumanence of the matte layer above it as a track matte.
if you were hoping to use keylight to ‘finesse’ the edges a bit, but the high-con to act as a core matte, then do the above, but then, on a duplicate of the footage, w/o the trakcmatte, apply keylight to try and enhance the edges, not worring aout the inside matte that was taken care of by the core matte.
Kevin Camp
Designer – KCPQ, KMYQ & KRCW -
Yup. This has gotten me in the ballpark. Only now I can’t seem to finesse the edges without leaving a very thin white line between the foreground and the background edge – unless I use a white background – then no problem. But I need to use a gradient dark grey background and the thin white line is too noticable.
I’ve been trying to finesse the edge with Keylight.
Any thoughts?
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white edges seems a little unusual for keylight… can you figure out with layer has the edges by hiding them one by one?
it’s not you track matte layer is it? once defined as a track matte, it should remain hidden.
Kevin Camp
Designer – KCPQ, KMYQ & KRCW -
I did try turning off the various layers to see where this is coming from. While doing this I tried tweaking both mattes, but at the end the only thing that worked was to change my gradient background to hide the thing. And it looks pretty darn good (more than acceptable) – though I’d still like to know where that pesky white line is coming from.
But I’ll put it to rest for the time being.
Thanks
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When using Keylight’s despot, I have had the same problem with the annoying white line that is created along the edge of my mask between duplicated layers of footage. My solution that completely solves the problem is to raise the mask expansion on the top layer up as little as 5. This expands the mask subtly covering the white line division.
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