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Green Screen Basics for Web?

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Rory Keenan
Green Screen Basics for Web?
on Nov 3, 2011 at 12:41:00 am

I'm a documentary film editor with little experience on green screen or graphics.
I finished a film and the director shot some green screen footage he wants on the promotional web site.

I need a "Lay of the land" on green-screen keying.....and exporting video with an alpha channel.
The director shot several people walking or talking against a green-screen. He wants these people exported with alpha channels so the web designer can put this moving video over a "collage design" on the web site.
The people will likely be tiny on the webpage.

-What are the basics for green screen keying in FCP7 ?

-What are the basics on "garbage matting" the corners of the frame ?

-Any recommendations on exporting with an alpha channel ?

-If FCP 7 is bad for keying/alpha-channel export, is there a better application?

(I have limited knowledge of Motion or After Effects. I can spend time learning to key in one of those programs but I'd need some basic help to get started)

Thanks for tips on the basics


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Rafael Amador
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 9:11:50 am

Hi Rory,
Go to the FCP forum and type "Green screen", "Blu screen" or "Chroma key" in the SEARCH window.
There are tons of info about how to get it done in FC.
rafael

http://www.nagavideo.com


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Chris Tompkins
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 12:04:15 pm

Do they want the footage keyed out to overlay on a webpage????

You key out your quicktimes in AE or FCP or Avid or APP.

Export to Prores 4444 or animation w/ alpha.
Compress to .SWF file with alpha for the web.

They'll need flash to do the rest.

Chris Tompkins
Video Atlanta LLC


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Mark Suszko
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 2:23:13 pm

I thought this flash keying over the web page thing had died off already; it was hot for a few months like 2 years ago, just because it was new, but viewers rapidly became annoyed by it, because it wasn't often used with any taste. Maybe your guy has a better application in mind for how to employ it.

Anyway, if the footage is already shot, I find that with a little tweaking, the standard keyer in FCP is no slouch at doing this job, provided the footage is really evenly lit and properly exposed. If the footage is at all problematical, other keyers become the go-to for this, and you can still invoke them thru FCP, if you have them installed. A lot of folks prefer to do their keying in Apple Motion, where they may have access to more keying tools. You may also find that before you key, you'll want to do some tweaking around in the 3-way color corrector or Apple Color, to optimize the footage first.

The 8-point garbage matte filter in FCP is very nice and intuitive to use, and you can keyframe it if needed. But first try using just the normal image cropping tools in the FCP motion tab to cut out unwanted junk in the scene.


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Rory Keenan
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 5:45:14 pm

Thanks guy these tips are great.

"You may also find that before you key, you'll want to do some tweaking around in the 3-way color corrector "

I saw this same tip on older posts about green-screen.
What am I correcting for in the 3-way color corrector?
Do I make the image slightly more magenta, adjust brightness levels.......what am I tweaking for?


"If the footage is at all problematical, other keyers become the go-to for this, and you can still invoke them thru FCP, if you have them installed. A lot of folks prefer to do their keying in Apple Motion, where they may have access to more keying tools."

  • What do you mean "Invoke them thru FCP?
  • I've seen several suggestions for other keyers. Using Apple Motion sounds good because it means I won't need to buy software for this project (I also have After Effects ). I've never used motion, know of any tutorials on keying in Motion? Any tips on starting it?


Within the Filters folder, what sub-folder is the "8-point garbage matte filter" located in"?


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Rory Keenan
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 5:54:50 pm

Thanks guy these tips are great.

"You may also find that before you key, you'll want to do some tweaking around in the 3-way color corrector "

I saw this same tip on older posts about green-screen.
What am I correcting for in the 3-way color corrector?
Do I make the image slightly more magenta, adjust brightness levels.......what am I tweaking for?


"If the footage is at all problematical, other keyers become the go-to for this, and you can still invoke them thru FCP, if you have them installed. A lot of folks prefer to do their keying in Apple Motion, where they may have access to more keying tools."

  • What do you mean "Invoke them thru FCP?
  • I've seen several suggestions for other keyers. Using Apple Motion sounds good because it means I won't need to buy software for this project (I also have After Effects ). I've never used motion, know of any tutorials on keying in Motion? Any tips on starting it?


Within the Filters folder, what sub-folder is the "8-point garbage matte filter" located in"?

How do you use "multiple layers" or "multiple instances" of the keyer to key problem areas separately?
I've seen suggestions about that in older posts like this one:
"you don't have to get everything in one pass: you can invoke multiple instances of the keyer and composite them in the FCP timeline so as to treat one troublesome part separate from the rest."

Can anyone clarify how to do this (I think I may have problematic footage)


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Stephen Smith
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 6:03:48 pm

I'm not a fan of the keyer in Motion. Motion 5 got a better keyer but I have not used it. I love Keylight which comes with AE. The FCP keyer is okay but it is not good with hair and glass.

Stephen Smith
Utah Video Productions

Check out my Motion Training DVD

Check out my Motion Tutorials


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Mark Suszko
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 7:14:07 pm

Rory, you're asking us to cram several books up your nose as if this is the Matrix and you can just upload perfect knowledge instantly. "woah, I know karate!" Not going to happen like that. Expect to spend days or weeks learning this and learning by doing. And step one is to RTFM, there are actually good instructions in the FCP manuals for all these things you're asking. The only way to get it done faster is to hire one of us to do it FOR you. That said, I'll try to answer your questions, but really, you have to do this on your own.

Still, I'll try to answer some of your many questions, since I seemed to have provoked most of them:-)


In the 3-way color corrector, you would be trying to refine the green screen to make it as even and well-saturated as possible, without affecting the rest of the people in the image, so the keyer has the best initial information to work from. And you try to work in a deeper color space than DV, which is very difficult to pull a good key from.. One of the tricks to working with bad chromakey footage is to use the 3-way color corrector to deliberately over-do the green. Then you make the matte based on this version of the footage, but apply it in a layer to a different, good quality normal colored version of the same scene, to make the best matte/mask combination.

Chromakeyers can sometimes be stand-alone programs that work indepenedently of the NLE. Some can work both as stand-alone and as a plug-in. You "invoke" them or call them up by navigating to your video effects menu, then dropping down the list to "keying", where you'll find luminance keyers as well as chromakeyers.

Apple Motion is a compositing program; it specializes in layering tracks of video, so it is a natural place to put a chromakey effect together with the new background and then export the finished product back to the NLE timeline or whatever. But if you have never touched Motion before today, I doubt you'll do much better than staying within FCP. But a great crash course in Motion is the DVD turorial "Moving with Motion" by COW expert Stephen Smith, who has saved my bacon enough times to equal a whole hog. Get that DVD and by chapter 13 you will be a Motion whiz yourself. But realize it doesn't spend a whole lot of time specifically about keying. Motion may have more chromakeyers and tools installed, though. Like a spill suppressor, which counters the rim of reflected green or blue light that may be seen on the edges of talent that stood too cose toa too-bright screen.

Multiple instances means using the same thing several times on different areas of the screen. In the FCP chromakeyer, you get an eyedropper tool for sampling the green. You can touch and sample more than one time, building up a better and better profile of the color you want keyered out... I use that as a starting point, then I use the visual graphic interface of the keyer to manipulate the control sliders manually, to further refine my key. In a really bad situation, I might mask off all but one part of the scene and just make the best key I can of that part, then bring in another copy of the scene and work my magic on a different parts. Build up the scene until allt he aprts are keyed as best as you can, and that's what I mean about multiple iterations.


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Rory Keenan
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 8:03:50 pm

Thanks so much for your help Mark.

I realize I'm asking for a "crash course".....but even a "crash course" will take some time.
I'm prepared to spend a week doing tutorials and experimenting with the footage they shot.
I just need to know where to start.......and you guys have given me some places to start.
If I can't get pretty close in a week, I'll tell the director we need to hire one of you guys.

I'll start in FCP today & tomorrow (using your suggestions).
If I hit a wall I'll be back here bugging you guys.

If the footage is too problematic for FCP then I'll go to another application.

Correct me if I'm wrong:
I get the impression that keying in Motion is a little easier than keylight.
Keylight is probably harder to learn but produces better results.
Do I have that right?

If the FCP keyer isn't producing satisfactory results I'll start tutorials on Motion or Keylight.


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Rory Keenan
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 6:03:44 pm

Yes, they want the footage keyed out to overlay on a web page.

Is there any particular codec I should be working in that's better for keying?
I think the footage was shot on a Panosonic P2, in 1080 at 29.97fps, I think it's DVCproHD.
Should I transcode to another codec?


"Export to Prores 4444 or animation w/ alpha.
Compress to .SWF file with alpha for the web."


How do I do this?
Correct me If I'm wrong: it sounds like I export in the FCP Export settings as Prores 4444.
Then I use compressor to save as an .SWF file with alpha for the web.
Do I have that right?


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Stephen Smith
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 6:16:05 pm

I would use the Animation codec, it will work for someone on a PC and a mac. You don't need to compress it as a .SWF file. The Flash person will do the compressing. They will most likely want it uncompressed. Flash will compress the footage with the background when the web guy is done with it. We just give it to them as an Animation - millions +. To do that in FCP go to File, Export, Using Quicktime Conversion. Click on the Options button. Set the Video to Animation. Make sure the Compressor setting is set to Millions of Colors +. That is what will give you the alpha channel. Thats it, you don't need to do anything else, the Flash person will know what to do from there.

Stephen Smith
Utah Video Productions

Check out my Motion Training DVD

Check out my Motion Tutorials


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Rory Keenan
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 6:31:51 pm

Great advice.......Thanks!

I've never used Keylight..... Is there a tutorial on-line?
I think I'll start with the keyer in FCP.
If that doesn't work I'll try Keylight


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Rory Keenan
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 8:29:49 pm

Thanks for the links to tutorials Stephen
Now I have a really bone-headed question.

I went to the link for those tutorials you suggested.
However the video tutorial won't play.

I clicked on the icon that says: "Play the Video Tutorial Here"
A new page loads and there is a blank area where video should be (no play controls either)
Am I doing something really dumb?
Do I need to subscribe to something (or pay) to play the tutorials on Creative Cow?

I can't believe I'm asking for help on watching a web video, but there it is.

Thanks for your patients guys.


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Mark Suszko
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 8:31:24 pm

Update your flash and quicktime, brah.


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Romeo Rubio
Re: Green Screen Basics for Web?
on Nov 5, 2011 at 7:22:13 pm

Definitely try to do the chroma keying in FCP first before you go to an outside program. Might as well stay in FCP if it works fine, right? I've had good results with FCP's chroma keyer, even with uneven color/shadows on backdrops. Just gotta do some tweaking to the settings in the keyer to get the entire range of the backdrop.


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Brad Wright
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 2:18:53 pm

There are several good books out there for keying. I recommend the Green Screen Handbook by Jeff Foster or Steve Wright's books. The most important thing about green screens to know is that your green screen should be perfectly flat and evenly lit. Sure, there's people that will tell you that there software fixes these problems. However, if you ask an expert, they will tell you the exact same thing. Even lighting and a flat background.

Brad Wright is software engineer, so often hard to figure out what he is talking about. He is always happy to explain answers further.


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Stephen Smith
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 2:58:27 pm

[Chris]

Export to Prores 4444 or animation w/ alpha.
Compress to .SWF file with alpha for the web.


Can PC guys use Proress 4444 in Flash? If yes that is great news. Every time I do this they want Animation with Alpha. They then bring it into Flash and let flash compress it when it makes the website.

Stephen Smith
Utah Video Productions

Check out my Motion Training DVD

Check out my Motion Tutorials


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Chris Tompkins
Re: Green Screen Basics for Web?
on Nov 3, 2011 at 3:30:04 pm

I don't think so, don't know for sure.
Prores and WIN.

Chris Tompkins
Video Atlanta LLC


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