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Merete H
Chroma key
on Apr 13, 2005 at 1:03:16 pm

Does anyone know a good site about chroma keying? I need input...



Merete


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Charlie King
Re: Chroma key
on Apr 13, 2005 at 3:04:01 pm

If you can tell us what systems you are using, what kind of invironment, I might be able to help, but I don't know of any sites that explain everything about chroma Keying. Just about every project has it's own little quirks that have to be overcome.

Charlie


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Merete H
Re: Chroma key
on Apr 14, 2005 at 9:22:13 am

I


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Jon Zanone
Re: Chroma key
on Apr 14, 2005 at 11:42:00 am

Don't use DV. As related by others much smarter than I in this very thread, DV is a bear to key. DV is a compressed format, and the part of the signal you need to make a good key is thrown away in the compression process.

Jon


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Mark Suszko
Re: Chroma key
on Apr 14, 2005 at 3:43:07 pm

I think you're hosed, between the DV and the shutter action, you might be trying to key one field's worth of image info in each of those motion frames. For the frames that are not working, You will need to hand-rotoscope those. You can export a frame movie into Photoshop, or use a paint program or compositor (hopefully with a wacom tablet and pen) to draw sharper mattes around the hand and finger, etc.

In DV, keying off green tends to work a little better than blue, as you have more luminance info with green. One other trick you might try is to do a luma key instead of a chrmakey, or combine the matte generated in luma over the chroma matte. Anything to avoid the tedious hand-roto work;-)


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Dave LaRonde
Re: Chroma key
on Apr 13, 2005 at 3:06:03 pm

A good chroma key starts with proper lighting. Try this:

http://www.film-and-video.com/broadcastvideoexamples-greenscreen.html

If you're using an NLE or a compositing application to pull the key (and who wouldn't?) you can get the basics here:

http://www.kenstone.net/fcp_homepage/chroma_key_fcp_hd_monahan.html

It's for Final Cut Pro, but you can find a couple of handy links to other applications. Or you can spend a half-hour refining a Google search to get what you seek.

And God help you if you're trying to key consumer-grade DV. It's a right royal pain in the neck, and you will spend several frustrating hours getting it right.


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Mark Suszko
Re: Chroma key
on Apr 13, 2005 at 7:17:27 pm

I would add the Ultimatte web site is often the first place for beginners to look up info on chromakeying.


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Charlie King
Re: Chroma key
on Apr 14, 2005 at 3:09:22 pm

Fast movement will always cause problems, the blur between fields of thesource and background tend to mix together and as a result will either key out or leave greenish trail. That is where you either live with it, or paint it out frame by frame. I personally don't know any other way to get rid of that problem, altho the better quality the camera you start with and the less compression you use the better the results.

Charlie


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