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AcesHigh87

macrumors 6502a
Original poster
Jan 11, 2009
986
326
New Brunswick, Canada
So I'm kinda noob when it comes to chroma keying, I'll admit. I've never had the money for a green screen so have never done it.

Software wise I know the process and have the software so that's no the problem. What is, is finding something to make a green screen out of.

So, I had a thought today. During my youtube show my friend will be vlogging across the room in front of his 42" TV. We were just going to leave the screen blank but I had an idea when I looked at it. Why not hook the TV up to the computer, put a pure green image on the screen and then green screen behind him?

What I want to know before we bother filming things is, does anyone think this could work? It's not a usual green screen tactic and I'm iffy on if it will work but has anyone ever tried?

Also, to point out not that I think it would matter. It's an LCD TV and he'll be recording 720p but off his phone so good resolution but maybe not great quality.

--Aces
 
By all means it should work, maybe not well though, since it is also a light source. I've used blue blankets, blue t shirts, green tablecloths, etc. However, the tv may cause some problems like I said, due to the fact that it is emitting light. Though if you can manually white balance, it might go well. But from a phone...well just be the judge. If the picture looks fine on the phone, it'll work okay.
 
You might get interference with the refresh frequency of the TV. Just give it a try... If you have interference, you might play around with shutterspeed of your camera, if you have that option...
(or use a lower frame rate if selectable)
 
You might get interference with the refresh frequency of the TV. Just give it a try... If you have interference, you might play around with shutterspeed of your camera, if you have that option...
(or use a lower frame rate if selectable)

I doubt his camera has it being a phone and all but I'll look into it if that problem arises.

We tested it on his computer screen and found that the green never stayed a stable color, it seemed at least. While it looked like one solid color hen we went to remove it we had over 5 keys and still a bit of green left. Hopefully on the larger, higher quality, screen this problem will be fixed. Plus our lighting created a lot of shadows which likely wouldn't help.

@MacStu, I'm pretty sure you can white balance his TV which might help as you said. What do you think we would balance it to though?
 
It will work, but your biggest worry will be spill. If I understand you correctly, the subject will be stationary in front of the TV (greenscreen). If that's the case, then the TV is also acting like a huge green softbox, emitting light onto your subject. So just watch out for that. Also, make sure you hit the subject with enough light from the front. And if the TV has a glass front, watch out for glare.
 
It'll work but not well at all. My recommendation... Go down to a local fabric store and pay the $15-20 it costs to just buy a big sheet of bright green fabric. Using the tv will work but there are two issues- 1) It emits light and green screens don't emit light so you will probably run into a lot of issues with the main character having parts of their body being keyed out because the green will reflect on them and 2) The refresh rate. You'll see lines moving up and down the screen because of the refresh rate so you're better off buying the fabric and just duct taping it to a wall or something.
 
If you are using a green screen and already going into compositing, why bother with green on the tv?

Just composite and track your image onto the screen.

I've done this many times as our camera crews (reality tv) can't chose what people are watching on tv when they need to shoot.
 
something that really worked for me on a budget was I went to walmart and bought just a bedsheet that was green. I pinned it to my wall and it works like a charm.

You will also need some solid lighting to avoid shadows.
 
Thanks for the advice everyone. We might try some test shots to see if it will work but if it doesn't we just won't bother with the screen unless we find ourselves at a fabric store. We only considered it because of convenience and random thought that it might work. If it doesn't, it doesn't, no big loss.
 
If you are using a green screen and already going into compositing, why bother with green on the tv?

Just composite and track your image onto the screen.

I've done this many times as our camera crews (reality tv) can't chose what people are watching on tv when they need to shoot.

He's not trying to composite something on the TV screen. He's trying to use the TV as a greenscreen itself.
 
He's not trying to composite something on the TV screen. He's trying to use the TV as a greenscreen itself.

In that case, feed the tv screen with what ever image you want to key the person in front of with the laptop....no need for a green screen at all. Pre-production and planning is the key.
 
In that case, feed the tv screen with what ever image you want to key the person in front of with the laptop....no need for a green screen at all. Pre-production and planning is the key.

That would only work if they framed the shot where the TV encompassed the entire frame.


Either way, as already mentioned, a piece of green fabric will work much better.
 
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