8 Bit Noise From Keys

[user_deleted]

Hi there, I'm keying uncompressed 8 bit HD footage shot against green. When the key is made the footage really deteriates in the none green areas. Huge ammounts of noise appear and pixels..

I usually switch matte back into the original footage but can anyone tell me why this happens cos it makes the footage look crap!

[user_deleted]

well, it depends how the footage was originally shot and how you key it (maybe to some compressed codec and you use keylight? then it's compression artifacts i guess).
if you put up a lossless frame and your script it might be easier to give you sound advice.
++ chris