there are two ways… the easiest way is usually to set the screan matte>replacement method to ‘hard color’. you may need to select replacement color to one that is closer to color of the skirt (just click the color chip under replacement method).
another way is to use an inside mask to set the area that you do not want keylight to effect (or want key light to effect differently from the edges). an inside mask is like a core matte, it involves creating a separate matte or a mask that contains the area that you want to keep (not key).
the manual for keylight describes one method to create an inside mask using two instances of keylight on the same layer, the first is a really ugly highly choked matte that the next instance of keylight uses as an inside mask.
another way is using aharon rabinowitz’s ‘super tight junk matte’ technique to create masks on the layer that can then be choked and softened (via the mask properties) to create a similar ugly choked key that you can use as an inside mask for keylight. the mask method processes much faster, but if your super tight junk matte is pretty complicated it can be a little difficult to work with… but if you already created it for the edge matte, you caan quickly copy and paste them onto the footage, tweak the expansion/feather and see how it might work.
if you don’t know what a ‘super tight junk matte’ is, check out the ae tutorials. it’s a very useful technique for getting good keys.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW