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 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 different treatment, and the second half of the sentence, about the shoulders, is what prevents the usual outcome. Send the footage as it came off the camera, not an already-keyed export.
There is a green edge around the hair. Get rid of it without cutting into the shoulders or the clothing.
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, each one reviewed on a real frame at full size rather than applied and accepted. In the session behind this article it:
- Measured the screen colour from the frame to build the key rather than using a default.
- Checked the alpha channel itself when the transparency appeared to be missing, instead of re-keying.
- 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, so 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.
When does this not work well?
When the screen was lit badly enough to tint the subject. 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, and motion blur defeats erosion, because a fast-moving edge has genuinely mixed pixels.
Common questions
How much erosion is safe? A pixel or two. Beyond that Vizard Agent is changing the silhouette rather than cleaning it.
Can it fix an already-keyed file? Only by painting over the fringe. Send Vizard Agent the original footage if you have it.
Why did the transparency disappear? An intermediate file dropped the alpha. Vizard Agent verifies the channel rather than re-keying.