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Mask edge Problem

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simonjrogers

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  • Joined: Wed Apr 20, 2016 1:33 pm

Mask edge Problem

PostTue May 10, 2016 10:13 am

Hi,

Im new here, Just trying to get to grips with Fusion after years with After Effects.

Im having an issue with the edges of masks. They appear to have a white line around the outside and when I try to feather the edges, depending on whether the mask is inverted or not I either get a dark or light outline.

Is this a normal issue or am I doing something wrong?

Cheers

Simon
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Sam Biddle

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  • Joined: Wed Feb 03, 2016 4:09 pm
  • Location: London

Re: Mask edge Problem

PostTue May 10, 2016 4:58 pm

Sounds like a premult/unpremult issue;

http://www.spherevfx.com/written-traini ... ed-images/

Use an Alpha Divide node (ADv) or Alpha Multiply node (AMl) depending on whether you're getting dark or light edges.
Sam Biddle
3D Artist @ BlueBolt VFX
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Jaydog

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  • Location: Sunshine Coast, Australia
  • Real Name: Jayden Lawson

Re: Mask edge Problem

PostMon Apr 10, 2023 4:18 pm

Had the same issue. I was cropping my video, and I found that adding sharpening was the issue. I removed the sharpening, made a new compound clip from all the affected videos, and then applied sharpening to the compound timeline, which fixed it.
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GalinMcMahon

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Re: Mask edge Problem

PostMon Apr 10, 2023 10:08 pm

How timely! I cut out part of a frame grab in photoshop. Removed all of the image except for a small portion I wanted to bring back in to DR. Exporting as a png put a black background on it. Usually setting it to screen would work but it didn't. The closest was lighten but that made the rest of the image about 50% opaque. Exported it as a psd with an alpha layer and got the white line after much tweaking.

Is there a useful reason for having to do a workaround for such a basic process? I would think that any graphics software would default to NOT putting white or dancing lines around an overlay and that you'd have to use a workaround to mess it up.
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Sander de Regt

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Re: Mask edge Problem

PostTue Apr 11, 2023 6:41 am

It might have something to do with your export settings. PNGs can have embedded alpha in them, so there shouldn't be this much fiddling.
Sander de Regt

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Chad Capeland

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Re: Mask edge Problem

PostTue Apr 11, 2023 5:06 pm

Yeah, by spec, PNGs should have straight (unpremultiplied) colors. Fusion will (though this is a new behavior) multiply the color on import. So you basically have to have whatever tool is exporting the PNG not premultiply.
Chad Capeland
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