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Green Screen Generator


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#1 Michael Nelson

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Posted 21 February 2010 - 09:37 PM

I do some work that involved shooting at TV monitors (LCD or Plasma) who have images placed in them in post. A common solution has been gaff in the corners of the screen to use as tracking points or, at times, cutting green paper out to fill the screen and then have it keyed out later.

In an idea world I see a device that generates nothing but a green screen. It would be a big as a computer thumb drive, run off a battery, have a HDMI, s-video, or composite RCA, to plug right into the TV.

Does this exist?

Another solution would be to have a DVD with an hour of Green burned to it and it could be played through the TV.
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#2 Logan McMillan

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Posted 21 February 2010 - 11:21 PM

I do some work that involved shooting at TV monitors (LCD or Plasma) who have images placed in them in post. A common solution has been gaff in the corners of the screen to use as tracking points or, at times, cutting green paper out to fill the screen and then have it keyed out later.

In an idea world I see a device that generates nothing but a green screen. It would be a big as a computer thumb drive, run off a battery, have a HDMI, s-video, or composite RCA, to plug right into the TV.

Does this exist?

Another solution would be to have a DVD with an hour of Green burned to it and it could be played through the TV.


I'd use either a DVD with a green menu with no buttons - and that is all thats on it - no need for an hour of footage.

Or a laptop connected to a TV with a green desktop on the TV and nothing else.
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#3 dusty mccord

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Posted 21 February 2010 - 11:26 PM

I'd use either a DVD with a green menu with no buttons - and that is all thats on it - no need for an hour of footage.

Or a laptop connected to a TV with a green desktop on the TV and nothing else.


The Chroma key green screen trick is easier than you think.
This the how I do my own Chroma green DVD's or computer screens in a pinch.

In photoshop create a new document that is the aspect ratio you will need for your TV/Monitor.
Fill that new image with a solid. Color that solid with an RGB value of 0 red, 0 Blue, and 255 green.
export that to a PNG.

Bring that PNG into your dvd authoring software and make sure the software knows what aspect ratio that image is suppose to play as.

Burn that DVD and now you have a Chroma Green DVD that should play green until you turn off the dvd player.

for a super quick green screen for a computer monitor.
hook that monitor up to a compute with photoshop after you have created the green screen image.
in photoshop hit 'F' on the key board to go into full screen mode. Zoom in with 'Command' and '+' or 'Control' and '+' for windows and hit tab to get rig of your tool windows.

make sure your screen saver is turned off.

Enjoy!
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#4 Ben Syverson

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Posted 22 February 2010 - 12:46 AM

From the compositor's perspective... If you're going to put anything on that screen, it should be four small white "+" signs in each corner, against a black background. Any reflection or light hitting the screen will key perfectly if it's against black, and the crosses will let you motion track anything onto the screen.

If you have talent passing in front of the monitor, you'll have to rotoscope, but that's preferable to getting footage with a blown out green screen and having to fake the reflection.

If you really have a lot of foreground subject passing in front of the monitor, especially with fine detail, you can fill the screen with a dark green, but don't do a 100% green. A dark green will still let you pull the reflections.

Edited by Ben Syverson, 22 February 2010 - 12:48 AM.

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#5 Gregory Almond

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Posted 11 March 2010 - 10:39 PM

We once had art department use chroma green paper to fill the screens rather than using the screens themselves to display. Using a monitor to show green means light is being shown onto your actors, causing spill issues.

It would be a good idea to use both green and use a + sign in the middle and L shapes in the corners for tracking simplicity.
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#6 John Brawley

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Posted 11 March 2010 - 11:48 PM

Burn that DVD and now you have a Chroma Green DVD that should play green until you turn off the dvd player.



Don't forget to add some tracking markers in the corner for extra compositing joy.

jb
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#7 Phil Rhodes

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Posted 12 March 2010 - 06:51 AM

Of course, if the green doesn't flicker, you might as well just have played back the real footage...

P
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#8 Oliver Christoph Kochs

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Posted 12 March 2010 - 04:12 PM

Please don't. Reason: The green light emission from the monitor creates a lot of spill (it's a lightsource rather than a cloth that is illuminated by light). You will end up keying information you still need. Also the green helps little to zero for your tracking. I'd use a light grey almost white, empty screen on the monitor and composite the footage with "multiply". I found tracking markers to be superflous because the monitor has the corners and these are what you pin on. If the monitor is a tube type be sure to bulge your image correctly to the convex glass.
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