I green screened my subject outside and keyed it in AE by using the multiple color keys and using keylight. Now I have a black outline and a little bit of white pixels on the edge of my subject. How can I correct this?
What kind off footage did you shoot? HDV? If you did, you may have to convert the footage to a different codec BEFORE you try to pull the key:
Dave's Stock Answer #1:
If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, AVCHD, mp4, mts, m2t, H.261 or H.264 -- you need to convert it to a different codec.
These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.
In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
If you can get by with ProRes -- yeah, I know it's iffy for you -- that's your best bet for a Mac that also runs FCP. Other good ones are Quicktime's PNG codec (lossles), Animation (big file size, still lossless), Photo JPEG at best quality... and then DVCPro HD.
But that's just me. Someone else may have a different order of preference for different reasons.