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what is best method for keying green screen with two shades?

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tony haerwhat is best method for keying green screen with two shades?
by on Nov 2, 2010 at 8:44:40 pm

I'm shooting this music video in front of a green screen curtain and with a green paper floor and was just wondering what was the best way to key out both floor and curtain? Also any suggestions how i can fix green screen overspill on the mans tights would be greatly appreciated?

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Dave LaRondeThere's more going on here than just two shades of green
by on Nov 2, 2010 at 9:50:58 pm

To begin with, I see more like eight basic shades of green. I would key each subject separately, and perhaps parts of their bodies separately. I recommend searching the COW for Aharon Rabinowitz' tutorial on creating super-tight junk mattes.

I also see the footage is probably something like 1440x1080, which implies it was shot in HDV, which is going to be very problematic at the edges of your subjects.

In order to cram an HD picture into the bitrate of an SD DV picture, HDV compresses the snot of the signal. One of the things to go is color resolution: the picture you posted has one-fourth the color information as luminance (B&W) information. And what do you need to pull a good chroma key? Accurate color information. Oh, there's enough there to fool the eye, but not a computer. You'll notice it most at the edges of your subjects.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Michael SzalapskiRe: There's more going on here than just two shades of green
by on Nov 3, 2010 at 12:25:26 am

This explains more what Dave is saying about color resolution.

Here's the super-tight junk matte tutorial Dave mentioned.

Here are some general keying tips.

Here are some tips on getting a better Keylight key.

Here are some tips on getting a key with a bad screen.

As far as the spill goes, if you're not using Keylight you might consider just using the Hue/Saturation effect and just effect the green range and desaturate it or use the spill suppressor effect.

- The Great Szalam
(The 'Great' stands for 'Not So Great, in fact, Extremely Humble')

No trees were harmed in the creation of this message, but several thousand electrons were mildly inconvenienced.


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tony haerRe: There's more going on here than just two shades of green
by on Nov 6, 2010 at 3:46:59 pm

thanks looked through the info it was very helpful. I need to just kill the spill i think first, what is the best tool in keylight just to make his tights not reflect so much green? tried the hue/saturation effect but it wasn't good enough and i am using keylight, unless you know of a better keyer for HDV footage?



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tony haerRe: There's more going on here than just two shades of green
by on Nov 6, 2010 at 12:29:26 pm

RE: One of the things to go is color resolution: the picture you posted has one-fourth the color information as luminance (B&W) information

can you elaborate on what i need to do regarding colour information please?



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tony haerRe: There's more going on here than just two shades of green
by on Nov 6, 2010 at 3:51:55 pm

RE: One of the things to go is color resolution: the picture you posted has one-fourth the color information as luminance (B&W) information


if i was to key out different parts of their body what is the most efficient way of putting all the layers together again can i just plonk mask layer upon mask layer.

Also to fix the edges how can i go about that the best way?

Is there a better keyer for HDV out there?



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tony haerRe: There's more going on here than just two shades of green
by on Nov 6, 2010 at 4:36:03 pm

RE: One of the things to go is color resolution: the picture you posted has one-fourth the color information as luminance (B&W) information


to fix the edges how can i go about that the best way?

Is there a better keyer for HDV out there?

Also i take it the workflow is this:

colour correct green for overspill
create keys with keylight and create tight garbage mattes for diffeent body parts
do a track matte on new comp of garbage matte comp and real footage?



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Danny HaysRe: There's more going on here than just two shades of green
by on Dec 3, 2010 at 4:18:29 am

There once a keyer from Nantucket,, I mean Ultra 2 from Serious Magic. Adobe bought it several years ago and released it with the high end CS3 bundles, then nothing with CS4 and now CS5 has it as a pluggin in Premiere. It doesn't have all the same parameters but it still works well. I have been able to key what was considered to unkeyable footage with the original version. Even better than Kelight, and with HDV. If you want to send me a small enough clip in the native format that Yahoo mail can handle, 10m I think, I'll test it for you with Ultra. Send me a background too if you want. danhays2004@yahoo.com Danny Hays, Universal Studios FL.



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