Green spill appearing on Precomped alpha matte
by Derek Shin
on
Jan 18, 2008 at 11:47:19 am
[CS3/Keylight] I pulled a perfect key on 4:2:2 footage -- precomped an edge/core key and used this edgecore.precomp as an alpha track matte to the source to apply spill suppress later. This comp (called "Keyed.precomp") has 2 layers in it, the original footage and edgecore.precomp alpha matte layer, looks perfect. But when this Keyed.precomp is taken into the Master comp for Compositing, it suddenly has green spill on the edges. Tried to unmultiply, set matte, adjust hue and add more spill suppress with no luck.
This is a bit confusing, if the Keyed.precomp looks perfect, it should be able to drop into another Master comp and look the same.
Re: Green spill appearing on Precomped alpha matte by Dave LaRonde on Jan 18, 2008 at 6:39:49 pm
[Derek Shin]"This comp (called "Keyed.precomp") has 2 layers in it, the original footage and edgecore.precomp alpha matte layer, looks perfect."
Try adding AE's Spill Suppressor to the original footage in this comp.
Alternately, you could use Keylight and futz with it until you get your subject over a grayish-looking background... you don't need transparency, just Keylight's very good spill supression capabilities.
So why didn't you see the spill until you put it in that other comp? Probably because it's now over a different background. I'll bet it was there in your "Keyed.precomp" all along, but you just didn't notice it.
Re: Green spill appearing on Precomped alpha matte by Derek Shin on Jan 19, 2008 at 5:01:11 am
So today I did realize that the spill does exist ever-so-slightly in the Keyed comp, but it definitely is amplified when nested again into a master comp. For some reason, the alpha track matte picks up more of the edges than I would like, probably because it is not using keylights spill suppress and only looking at the alpha channel. Still don't know why it gets increasingly bad with each nested comp, I just added spill suppression twice and tweaked the edges as a temp fix. Any more info on this would be appreciated!
