How to get the green fringe off the hair after keying
Ask Vizard Agent to measure the spill colour off the actual frame rather than apply a standard key. The fringe around hair needs a harder edge treatment than the fringe along a shoulder, and a single erosion strong enough to clean the first will visibly eat into the second.
What is the short version?
Your green screen keyed fine at a glance and there is a green rim around the hair. Turning the key up removes the rim and part of the person with it. Vizard Agent treats hair and clothing as two different problems.
- Tell Vizard Agent where the fringe shows.
- Let it sample the real colour from the frame.
- Expect the mask to treat hair and clothes differently.
What do you need before you start?
The footage as it came off the camera, not an already-keyed export. A cutout someone else made has thrown away the information needed to do this properly, and the only options left are painting over the fringe or re-keying from the original.
If you know the lighting was uneven, say so. Green spill is worst where the screen was brightest and where the subject stood closest to it, and knowing that saves a pass working out why one side is worse than the other.
What do you type into Vizard Agent?
Describe where the problem is rather than asking for a better key. "Clean it up" gets a stronger key, which is the wrong direction; naming the hair points at the part that needs a different treatment from the rest.
There is a green edge around the hair. Get rid of it without cutting into the shoulders or the clothing.
The second half of that sentence is what prevents the usual outcome. A key tuned until the hair is clean has almost always taken a bite out of everything else by then.
What does Vizard Agent actually do?
It measures instead of guessing. The green value is sampled from the actual frame to build the key, and the mask is then adjusted in small, testable steps with each one reviewed on a real frame rather than applied and accepted.
In that session the work ran:
- Measured the screen colour from the frame to build a clean key rather than using a default.
- Isolated the subject, then checked the alpha channel itself when the transparency appeared to be missing.
- Reduced the green halo around the hair while watching the facial features for damage.
- Eroded the mask edge by two pixels — enough for the halo, small enough not to change the shape.
- Found that a stronger erosion cleaned the head but cut into the clothing, and built a graded mask that treats the two areas differently.
- Rebuilt the mask against the video's actual first frame when a mask made from a reference still did not line up.
That last one is worth noting. A mask built from a reference frame and applied to a video that starts a fraction earlier is subtly misaligned everywhere, and the symptom looks like a bad key rather than a timing error.
What does the result look like?
A cutout that sits on the new background without a rim. The hair keeps its softness rather than being cut to a hard outline, the shoulders keep their shape, and there is no green in the edge pixels when you look closely.
Vizard Agent checks the edges at full size rather than in a preview. Green fringing is invisible at playback scale on a dark background and obvious on a light one, so the check has to be on the actual pixels.
When does this not work well?
When the screen was lit badly enough to tint the subject. Spill is not only at the edges — a green cast across a cheek or a white shirt is a colour problem rather than a mask problem, and it needs correcting separately.
Fine hair against a dark new background is the hardest case. The strands that made the shot look natural are exactly the pixels that carry the most spill, and there is a real trade between keeping them and keeping the edge clean.
And motion blur defeats erosion. A quickly moving hand has genuinely mixed pixels at its edge, and no threshold separates them correctly.
How do you fix a result that came back wrong?
Say which part is wrong and in which direction it is wrong. "The hair still has a rim" and "the shoulder looks chewed" are opposite corrections pulling against each other, and Vizard Agent adjusts only the region you name rather than moving the key overall.
If the whole cutout looks slightly off rather than fringed, check the alignment. A mask that does not start on the same frame as the footage produces a soft, hard-to-name wrongness, and matching it to the first real frame fixes it in one step.
If the file looks solid instead of transparent, the alpha did not survive an intermediate step. Ask Vizard Agent to verify the channel in that file rather than re-keying, which was the cause once in that session.
How does Vizard Agent compare to doing it yourself?
Every keying tool has a spill-suppression slider, and on a well-lit screen it is enough. When it is not, the manual answer is a matte built in layers, with different treatments for hair and body — which is the technique here and takes a compositor an hour.
The useful difference is testing each step on a real frame at full size. Most of the time in that session went on small, reviewed adjustments rather than on one big correction, and that is the approach that gets to a clean edge without discovering at the end that the shoulders have been eaten.
Common questions
Why is the fringe only around the hair? Because hair edges are genuinely semi-transparent, so they hold more of the screen colour than a solid edge does.
Can it just blur the edge? It can, and that usually reads as soft rather than clean. Vizard Agent prefers a measured erosion.
How much erosion is safe? A pixel or two. Beyond that Vizard Agent is changing the silhouette rather than cleaning it.
What if the shirt is light coloured? Then spill shows on it. Vizard Agent treats that as colour correction rather than masking.
Can it fix an already-keyed file? Only by painting over the fringe. Send the original footage if you have it.
Does the new background matter? Yes. Vizard Agent checks against a light one, because a dark background hides fringing.
What about motion blur? Erosion does not help there. Vizard Agent will say when a moving edge is the limit.
Can it keep the hair soft? That is the trade. Vizard Agent will show you both versions if you ask.
Why did the transparency disappear? An intermediate file dropped the alpha. Vizard Agent verifies the channel rather than re-keying.
Can I add a prop in front of me too? Yes. That is a separate keyed layer composited over the person.
How do I check it myself? Look at the edge at full size against a light background, which is what Vizard Agent does.
Does this change the audio? No. Vizard Agent keeps the original audio untouched.
Can it do this on a moving shot? Yes, though Vizard Agent finds a locked-off shot considerably easier to hold.
What if the screen was uneven? Vizard Agent measures rather than assuming one value, which handles mild unevenness across the screen.
Can I see the mask on its own? Yes. Ask Vizard Agent to output the alpha channel as its own video and the problem is usually obvious there.