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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Green Screen - Help Please

D

Dylan Reeve

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We shot some Green screen footage a while ago (two music videos and opening titles for a show, all in one weekend) - but I'm not having great luck with getting TIFs out that key well and look good.

Unfortunately I wasn't on set, and no one asked me ahead of time, or I would have told them to light with daylight-balanced, instead they shot tungsten.

The RED proxies look fairly good in skin tone, but pretty dull and lacking saturation in the green screen.

There's an example clip online here:
http://www.bunkermedia.co.nz/red/A009_C008_080406_001.R3D

Or via FTP:
ftp://ftp.bunkermedia.co.nz/
Username: red
Password: redred

This clip actually has somewhat more vibrant greens than some of the others, but they're all huge - so we'll go with this one.

If anyone can point me in the right direction for best foreground and green for keying, that would be great. Ideally in RED Alert, but REDCINE settings would be fine too.

Thanks!
 
weirdcrew said:
You might be better of exporting it as pdlog or redlog and grade it where you have secondaries as an option. So you can "separate" the green better.
Click to expand...

Something I will experiment with. Still need to get the basic settings in REDAlert sorted, because the Metadata and Defaults aren't great.

The green is pretty desaturated. And to do a good secondary on it I'll still have to be able to pull a decent key to be able to separate the green.
 
Saturating the green in post to pull a key from does not help at all. Never use a scondary to "improve" a greenscreen.

I would try two things:

1. No WB, use REDs native 5000k even the picture looks reddish.

2. WB to 3200k

I suppose that WB in Redalert does not help the later key.

I also would use REDlog since it its optimised for 10bit out and moves the histo more to the right, giving you more "flesh".

EDIT: A great GS does not necessarily look saturated green, on the contrary. Due to the high resolution and the lack of processing (thank you RED) one gets a desaturated looking GS as one would have with 35mm scans. On GS work the depth of the colour space matters, DR, the noise of course and artefacts induced by compression.
Shooting with RED unfiltered tungsten reduces DR (red clips much ealier), the noise in the blue channel is considerably higher but compression artefacts are not worse. In other words: The key can be ok when at least shot in 4K using the power of oversampling if downconverted to 1080p or even PAL.

Sorry to hear this and good luck.

Hans

(I never understand why people shoot tungsten GS with RED as they would never shoot tungsten GS with daylight balanced film).
 
Dylan,

When I put rec 709 on both camera input and output in project settings, you have plenty of green there. The wash out is just the RAW talking (it's like a film negative, grey and washed because it contains so much info).

Regards,

Fredrik Callinggard
 
weirdcrew said:
Dylan,

When I put rec 709 on both camera input and output in project settings, you have plenty of green there. The wash out is just the RAW talking (it's like a film negative, grey and washed because it contains so much info).
Click to expand...

Yeah that was the first setting I tried, as it initially seems to provide the best green, but it way over saturates the skin tones and foreground elements.

Also the noise in the blue channel with that setting is pretty extreme.

Sadly the clip I've uploaded isn't the best example of the problem-clips, but the others are pretty large.
 
The problem you have is white in the clothes - here's a green screen matte plate I quickly graded. Camera rgb and rec 709 in project settings. It's hard to get the yellow tungsten (that colors to green) light out of it with primary grading. I strongly suggest to take it to a secondary grading where you can separate the green screen.

regards,

Fredrik

1377_1208343583.jpg
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Boy, this is bad!

They shot it not only in tungsten but also 2k. Hopeless if you ask me. The girls hair will never key nicely. I gave it try with Shake and Keylight. Bad, bad artefacts to fight, colourspace is not too bad (did a WB native 5k in RC).

I for sure would reshoot (happened to me when I did my first shoot with HDCAM GS - reshot all the GS and used HDCAM never agin for GS).

Very sorry,

Kind Regards,

Hans
 
Hi Fredrik,

IMHO, in your picture the screen does look green now, but this is not the problem. I can pull a key off the reddish plate when developed at 5000K in RC easely. The Skintones get not touched. Colourspace and the differentiation betwenn "green" and skin does work although to the viewers eyes it looks rather similar.

What strikes me are the artefacts. I never knew that RED in 2K creates such bad artefacts. One can only fight this with softening borders, shrinking the matte etc... little but important things like fine hair details will get lost. No chance here for a natural composit.


Hans
 
Hans von Sonntag said:
What strikes me are the artefacts. I never knew that RED in 2K creates such bad artefacts. One can only fight this with softening borders, shrinking the matte etc... little but important things like fine hair details will get lost. No chance here for a natural composit.

Hans
Click to expand...

I know 2K is not nice haahaa why do you think they're coming with 5K hahaha. What I was trying to do was to completely separate them as much as possible and make a green screen pass. So you could key the girls hair as much as possible, maybe I over exaggerated hahaha. The artefacts is nothing to do with except for using methods as if you've shot DV. A DV green screen plug like for example DV garage or something, if you're lazy.

fred
 
weirdcrew said:
The artefacts is nothing to do with except for using methods as if you've shot DV. A DV green screen plug like for example DV garage or something, if you're lazy.

fred
Click to expand...

Yes. What they esentially do is blurring the blue channel. Does help a bit. Stiil far form what I expect from a GS footage (because I don't want anything blurred, I want fine deatil).

BTW, I had a great GS experience with RED: Daylight, 4K, oversampling down to 1080p and off you go!

Interesting that RED does not make filmmaking easier, cheaper perhaps. And sometimes more expensive when things go wrong.

Hans
 
Hans von Sonntag said:
Yes. What they esentially do is blurring the blue channel. Does help a bit. Stiil far form what I expect from a GS footage (because I don't want anything blurred, I want fine deatil).

BTW, I had a great GS experience with RED: Daylight, 4K, oversampling down to 1080p and off you go!

Interesting that RED does not make filmmaking easier, cheaper perhaps. And sometimes more expensive when things go wrong.

Hans
Click to expand...

The blue noise is a problem and has always been, the classic line now is to say maybe in the next build. It seems to especially manifest in tungsten light and in mid tones in low light situations, when the compression has to kick in. The compression noise then is unbearable.

Hopefully this will be solved with build 16 hahahaahaha

fredrik
 
The solution to colour temp problems could be to pull a key in the most forgiving colour settings for the GS, but output only an alpha matte.

Then, re-export the original clips with a grading that suits the skin-tones and scene in general, and combine that with the alpha matte from the original pass...

Won't help with compression artefacts or the like, of course, but may be of use as a workaround for some of your other issues?
 
Have you tried using Primatte Keyer?

There's also a very laborous manual technique in After Effects pulling multiple keys of the various shades of green... Had to do this on a feature... not recommended.
 
O.k I'm about to do a short GS shoot in two weeks time.

I don't do them that often (I'm primarily a wildlife doc maker)
What would you guys recommend so as to avoid the major pitfalls associated with the RED and GS?

Thanks in advance.
 
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