I have two layers where i have used the colorama effect combined with luma matte track matte to remove the sky (white areas) from the comp. Now i want to cut or slim the track matte due to hard edges, i tried simpel choker but no luck. What can i do to reduce the whole edges of a track matte???
simple choker works on the alpha of a layer, so applying it on the layer beneath the track matte, or on the luma matte/track matte itself won't work (neither really has an alpha at that point).
the most straight forward way to do it would be to pre-comp the track matte and layer being matted, then apply simple choker to the nested comp.
select the track matte and associated layer and choose layers>pre-compose. this will make those layers into a single layer (nested composition). add simple choker to that layer and you should get what you are looking for.