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Green Screen trouble

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Matt BilskiGreen Screen trouble
by on Dec 6, 2011 at 10:28:24 pm

Sorry if this doesn't follow the code here but I have a school project due tomorrow and I need an answer quick. But if anyone could help it would be greatly appreciated.

Alright, the story is I'm trying to key out green screen. But every time i try to key it out using Keylight 1.2 in AE CS5 and Ultra Key in Premiere CS5 on Mac, it somehow keys out the grain in the video. I have a Canon t3i and I recorded in 720p 60fps and have tried all different settings and nothing has seemed to work. Also, whenever I import footage to either program it says "This item has an unlabeled alpha channel." Not sure if that effects the way it keys it or not. I'm running lion.

The pictures are examples of what happens

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Kevin CampRe: Green Screen trouble
by on Dec 6, 2011 at 10:49:51 pm

[Matt Bilski] "Also, whenever I import footage to either program it says "This item has an unlabeled alpha channel.""

interestingly there was a post earlier today on this issue, you might check that thread out.

for keying, i would recommend converting the h.264 file to another codec, probably a lossless quicktime.

as for the grain issue, i think you are referring to the noise that can be produced with keylight's spill suppression/removal. if you search the cow, you'll find many techniques to get around this issue. a simple one that can often help is in the screen matte settings, set the the replacement method from soft color to hard color... you may want to set the color to a color that is closure to the color that is showing the most noise.

Kevin Camp
Senior Designer

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Matt BilskiRe: Green Screen trouble
by on Dec 7, 2011 at 1:21:28 am

I played around a bit and the soft color to hard color helped a lot. I was testing on different footage though and it was still a little noisy. And the some of the colors were wrongly keyed out. I'm going to get new lighting and that should do the trick. At least I think it will.. Thank you for help!

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Dave LaRondeRe: Green Screen trouble
by on Dec 6, 2011 at 11:43:38 pm

As Kevin says, there are a lot of ways to get rid of noise in a Keylight key. I like to simply pull a proper key (look in the Status view), and use that clip as an alpha matte for the duplicated footage with NO keylight applied.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA

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