Blue vs Green screen work

[Guest Ken Maskrey]

In school, I was taught: use green for digital, blue for film. But, after reading about colorspaces, and in particular, how HDV's 4:2:0 colrospace is actually an alternating (4:2:0 then 4:0:2) sampling, meaning that on one line it samples Y-U and the next Y-V, I can't see why there would be any difference between blue and green for HDV, or for that matter, any digital colorspace.

 

Anybody got some clarification on this? I'm not tied to an HDV here, I'm just using it as a reference...in addition, one teacher told me the wrong definition of 4:2:0, i.e. that Y-V is never sampled....

[Chad Stockfleth]

I've never heard to use green for digital, and blue for film. I use both in video and film projects. For me it has always been a matter of what your subject is that your are trying to key, for example if the talent has to wear a blue shirt, obviously you have to shoot it on a greenscreen and vice versa. I think either would be fine.

[David Mullen ASC]

Blue is a noiser channel than green, which is one reason for the preference for green, but it more depends on scene content. Film traditionally used blue instead of green mainly because it was somewhat easier to generate hi-con b&w hold-mattes for optical printer composite work, although green was used sometimes.