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Change fill to stroke – alpha matte?
Hey there, is there any quick/easy way to change an alpha matte / luma matte from being a fill to being stroked?
For example, I have a luma matte render of a CG character from C4D – so it’s white on black. I want to quickly make that into an outline instead of a fill. And yes, I realize I could render this out using the Cel Renderer in C4D. But I don’t always want to do that, and that may not work in some cases.
Here’s what I currently do:
– Use Set Matte (using Luminance) to change it from a luma matte to an alpha matte
– duplicate my layer, use Simple Choker with a positive value to cut into the matte
– set the Track Matte for my first layer (without the choker) to Alpha Inverted (using my 2nd layer as the matte layer)
– then, if need be, pre-comp both layers and add a Fill to change it to whatever colour I needThis seems like a lot of steps – is there an easier way? Also, it doesn’t work great if your element touches the edge of the frame, as it will then add an outline around there as well. Thanks!
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2 Replies
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Layer > Layer style > Stroke
Creates outline around the alpha, just like photoshop.
for keying out black matte, I Always use free plugin “UnMult” from Red Giant. -
Thanks Mohsen. Good ideas there. I had forgotten about UnMult – I’ll start using that again.
Re: using Stroke, that’s a good technique, but I find it has some flaws. I compared the result of that vs my method, and while they’re similar, using the Stroke layer style gives me a very aliased outer edge for some reason (I tried to attach a screengrab but it wasn’t working).
Also, I then don’t get JUST the stroke – it’s still filled as well. If I want to get it to work on top of other footage, I need to fill the layer with black, then put it on Lighten/Screen/Add, which is likely fine in most cases but not all.
Thanks for the tips!
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