Noise when Chroma Keying

[Fabiano Peres]

To solve this, on Keylight change the view to “Combined Matte” and at “Screen Matte” increase or decrease the values of “Clip Black” and “Clip White” try to get the bigger contrast of back and white possible…
The black areas are the ones that will not be seen in the final comp.

I hope it helps.

[Eddy Alvarez]

if you clip the black and whites in the screen matte section…do a screen pre-blur by half a point or third of a point..to soften any hard edges..

or add a simple choker effect at half a point…so your edges come smoother

[Derek Hader]

Its not my edges,

Its actually the face of the objects

[Fabiano Peres]

Clip black and white as I told you right before, it will solve the problem.

[Derek Hader]

Thanks for the advice and pointers

[Barend Onneweer]

If the noise is in the matte, then increasing the matte contrast by pulling the levels as suggested will help.

It sounds though as if you’re seeing amplified noise caused by spill removal. See if disabling the spill removal in Keylight helps.

FWIW – I usually apply a pass of Remove Grain before keying.

Bar3nd

Forum COWmunity leader for:
ADOBE AFTER EFFECTS
MAGIC BULLET SUITE
INDIE FILM & DOCUMENTARY

[Erik Pontius]

As others have said, use the status view to see how much to clip white/clip black. Also adjusting the screen strength option very slightly might help as well.
You might also find that you are having to clip black by a large degree to get the majority of the background to key (unevenly lit, wrinkles, etc…). I’d recommend following Aharon’s tutorial on super-tight junk mattes. This way you remove most of the background and only have to worry about a small portion to process with keylight. Also, Andrew Kramer’s tutorial on keylight is a good down and dirty intro to keylight.
Keylight will use a color to replace spill being removed, often adjusting this color from the default grey color may help.
Another option is to tell keylight just not to process the majority of the face by drawing a mask around the center of the face and setting keylight’s “inside mask” option to this mask.
Keylight’s thick manual is a good read as well as it goes into some of the more advanced features that might be of help as well (screen/alpha bias, color correction, etc…)

Erik