How to get keyed footage with alpha into Resolve

You pulled a clean key in one app and brought it into Resolve, and now there is a white fringe around the hair, or a dark halo, or the transparency is gone entirely and your subject arrives on solid black. The key did not break in transit. The handoff did, because carrying alpha between applications has three failure points and each one has a signature artifact.

The three ways alpha dies

The container drops it. H.264 and standard ProRes 422 have no alpha channel; export to them and the transparency is simply discarded. You need ProRes 4444, or EXR or PNG sequences.

The premultiplication is misread. Straight alpha stores the foreground at full strength with the mix left to the compositor. Premultiplied stores color already multiplied by alpha. Interpret one as the other and you get fringes: bright halos when straight is read as premultiplied, dark edges the other way. This is the classic white fringe, and it is a flag, not a keying error.

The gamma shifts. Compositing math assumes linear light. Merge soft edges in a display gamma and they land slightly wrong, which reads as a grey haze in semi-transparent areas like hair and smoke.

The clean path into Resolve

1. Export ProRes 4444 with alpha from your keyer. From Key Studio Pro, that is the ProRes 4444 output; the EXR passes are the higher-precision alternative when Fusion owns the comp.
2. Drop the clip on a video track above the background on the Edit page. Resolve reads the embedded alpha automatically and the composite just appears.
3. If you see fringing, open the clip attributes and flip Alpha Mode between straight and premultiplied. One of the two is right, and the fringe names the wrong one.
4. For finer control, use the Matte and FG EXR passes in Fusion, where you decide the premultiply explicitly with an AlphaMultiply or the Merge’s own handling.

Which pass to hand over

• Editor cutting a timeline: ProRes 4444 with alpha. One file, drag, done.
• Fusion or After Effects comp: straight FG plus the Matte EXR, so despill decisions and edge treatments happen in context. Note the FG pass is in the sRGB gamut; convert it to linear before combining it with the alpha.
• Quick preview for a client: the premultiplied Processed EXR, which drops in with no routing at all.

What the right handoff cannot fix

Premultiplication flags fix fringes born at the handoff. A fringe that was in the key itself, spill on the edge pixels or a matte that was already choked, rides along faithfully. If flipping the alpha mode changes nothing, the problem is upstream: spill or the keyer’s edge handling.

Double-premultiplication is the sneaky one: a premultiplied file run through a tool that premultiplies again gets edges darker than either flag setting can explain. If both modes look wrong in different ways, walk the pipeline and find the second multiply.

Common questions

Why is my clip on black instead of transparent?

The file has no alpha. Check the codec first; if it is 422 or H.264, the alpha was lost at export, not import.

EXR or ProRes 4444, which is better?

EXR carries linear float precision and separate passes, which comps want. ProRes 4444 is one convenient real-time file, which timelines want. Deliver by destination, or both; storage is cheaper than a re-export at 11pm.

Does Premiere behave the same way?

Yes: same containers, same premultiplication rules, with the interpretation under Modify, Interpret Footage. The fringe diagnosis transfers unchanged.

The edges shimmer over the new background.

If the matte itself chatters frame to frame, that is the key, not the handoff. See the motion blur guide for why edges chatter and what holds them steady.