FORUMS: list search recent posts

Should Green Screen be a Vibrant Green?

COW Forums : Cinematography

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Kevin Camin
Should Green Screen be a Vibrant Green?
on May 27, 2016 at 12:36:21 am

Hello,

I'm at a studio where we are moving into doing green screen work. I'll tell you what I know: the screen should be very evenly lit so that it's value is uniform and easy to isolate, keep the subject far enough away to reduce spill, keep the lighting on the subject off the green screen so that it doesn't affect the first point.

1. I was wondering if it is preferable to have a vibrant, saturated green? I feel like right now we are using somewhat of a dull green and I'm not sure if it's affecting the key. A dull green to me might be moving into color areas of tans or yellows. whereas a vibrant green is the farthest point from the other colors.

2. A green screen with video noise (high ISO) I'm assuming produces some keying problems.

3. Any tips on keying out feet that are coming into contact with the screen. I've always done a separate key and/or some rotoscoping if needed.


Any other tips would be greatly appreciated. Thank you.

Best regards,

Kevin Camin


Return to posts index

Mark Suszko
Re: Should Green Screen be a Vibrant Green?
on May 27, 2016 at 3:17:59 pm

Saturation is more important than brightness. Indeed, if the green is too bright, you'll have trouble distinguishing whites. Too saturated just increases noise. For the feet, a separate softbox is what we generally end up using.

My best "secret" tip for good greenscreening?

Shoot a Macbeth chart or printed color bar chart thru the lens of the camera, under the exact lighting conditions of the actual set.

Bring that into your NLE, and color-correct that chart using scopes.

Now, copy/paste attributes>color correction from that corrected clip, into your raw greenscreen footage, BEFORE applying the keyer.

Now key it.

BAM.

Awesome key, right out of the box; probably will not need a single tweak..


Return to posts index

Kevin Camin
Re: Should Green Screen be a Vibrant Green?
on May 27, 2016 at 4:34:37 pm

Thanks for the tips Mark. Just to clarify, is have a saturated green background vs. a duller green background better for key?

Best regards,

Kevin Camin


Return to posts index


Mark Suszko
Re: Should Green Screen be a Vibrant Green?
on May 27, 2016 at 4:46:43 pm

Without seeing them side-by-side, tough to say but I'd prefer more saturated, I guess. Depends on how *much* more.


Return to posts index

Chris Wright
Re: Should Green Screen be a Vibrant Green?
on May 28, 2016 at 3:21:22 am
Last Edited By Chris Wright on May 28, 2016 at 4:14:50 am

i made an AE template that pushes green into rgb 0,1,0 so that there's only one color for the keyer to see. it's in 32bpc
https://f1.creativecow.net/9925/9925

also, much above 60-70ire for newer cameras, and you'll blow out the chroma, leaving only luma which, you know, you can't key.

Red uses 60 ire for example. search the native ire and iso your camera records to as each camera sensor is different.
then decode RAW to EXR or prores 4k and denoise with neatvideo before keying.


Return to posts index

Alan Lloyd
Re: Should Green Screen be a Vibrant Green?
on May 28, 2016 at 5:01:32 pm

A good balance between luminance and saturation, as noted above.

I try to keep the green at about 50 IRE, and nice and even as you'd mentioned.

If you're doing head-to-toe you'll need to light for it, yes.

And noise is the enemy of a good key.

Beyond that, Chris's comments on specifics are useful.

Also, shooting at a decent bitrate and 4.2.2 color sampling are useful. AVCHD can be...interesting in a greenscreen setting.


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]