Green Screen on 60D- Picture Profile?

I can't confirm that, but I read on different occasions, that the "faithful" style produces the most accurate colour representation.
But IMHO the most important thing (next to a perfectly lit screen) is to turn internal sharpening completely down. Sharpening leads to picture artifacts on the edges that can give you a hard time in keying. Also avoid the 720p mode like plague for the same reason.

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"Tragedy is a close-up; comedy, a long shot." - Buster Keaton