Removing blurred matte color on animation

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arconz

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Removing blurred matte color on animation

PostMon Jan 24, 2022 2:33 am

I have 3D objects rendered with motion blur & alpha brought into Resolve Studio. The blur is showing the blurred background color (black) at the edges. (See animated red dot in the pic).

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I have recently switched from Premiere Pro which could easily get the proper transparent fade by adding "Remove Black Matte" and/or Set Matte effects. I have googled but can't find a similar solution in Resolve for this? Any help much apprec.
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Uli Plank

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Re: Removing blurred matte color on animation

PostMon Jan 24, 2022 3:28 am

Check the alpha settings in Clip Attributes.
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arconz

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Re: Removing blurred matte color on animation

PostMon Jan 24, 2022 3:47 am

That was the first thing I checked, its Premultiplied by default which shows the black blur, Straight alpha makes it worse.

If its relevant the animation is half-float 16-bit EXRs ACEScg. (ACES Resolve project as well).
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arconz

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Re: Removing blurred matte color on animation

PostSat Jan 29, 2022 4:27 am

Ok further testing has revealed this is likely a Resolve bug with ACES. Rec.709 content + timeline space & everything comps fine, no black halo. However a Rec.709 timeline kind of defeats the purpose of ACES...

To eliminate source imagery as a potential problem I tested from the Fusion page with a shape fill & zoom blur - works fine in a Rec.709 timeline but setting to ACES brings back the black halo around the blur.

Even with ACES Project Settings set to Rec.709 output (to match the monitor), it should still comp correctly internally and output a grabbed still correctly from the Color page? If that's a correct assumption then so as far as I can tell Resolve ACES workflows are only functional for footage or animation with hard alpha mattes, and any sort of blur effect is currently impossible :/
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Hendrik Proosa

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Re: Removing blurred matte color on animation

PostTue Feb 01, 2022 3:11 pm

Compositing with alpha needs proper linearization of RGB values to do the bg multiplication with inverted alpha correctly. My random guess is that this is what goes sideways in Resolve.

In Fusion, what was your working space when trying it out?
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arconz

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Re: Removing blurred matte color on animation

PostThu Feb 03, 2022 12:28 am

That comp was in the Edit page, with a red dot render on top of a blue background render. (or shape fill from the Fusion page in place of the dot render, same result). Input color space for the shape in Fusion was Auto, changing this parameter doesn't seem to make a difference.

Interestingly if I do everything from the Fusion page (inc background) it gets rid of the black edge but the edge blend colors are wrong (See pic)... Imported renders or a Fusion shape fill have the same issue:

Image

Interestingly with ACES color science I can only get a correct sRGB comp from the Edit page and not Fusion, regardless of color space settings. Not a real concern - it would be preferable to get ACEScg images working.

My node network is just a default Merge node with blue to BG and red dot to FG, is there some other node or setting I could try?
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