How do you test a green screen remover’s edges before export?

Put the same cutout over black, white, and your actual replacement background. Zoom in on hair and fabric. If a line changes with the backdrop, inspect the matte; if the edge stays green on all three, try spill correction. Scrub through motion before exporting.

A three-background diagnostic card

Duplicate one keyed frame into three panels and keep the crop and exposure identical. In the first two panels, use black and white. In the third, place the actual replacement plate. Mark the same edge in each panel. A dark line on white can disappear on black, and a bright edge on black can vanish on white. A green cast that remains on both is a reason to inspect color separately from opacity.

Is it leftover green or partial transparency?

Turn on the alpha or matte view. Check an area that should be opaque, such as the middle of a jacket. If the backdrop shows through there, repair opacity before changing color. If the matte looks solid but the jacket edge is green in the composite, reduce green spill on that edge. Keep the original and corrected frames side by side so you can see when the correction starts changing skin or fabric.

Why test three frames?

Pick one still frame, one at the fastest motion, and one when the subject passes through a shadow. For each, write down the location of the defect, which backdrop makes it visible, and whether it also appears in the matte. Change one control, then repeat the same checks. Stop when the edge looks stable against the actual plate and the correction has preserved the intended detail.

What if the editor preview looks clean?

Export a short sample using the settings you plan to deliver. Re-import it and composite it over the same test backgrounds. If the exported sample and the timeline behave differently, fix the export before changing the key. Check the delivery format’s alpha support when you need a transparent result.