Difference between revisions of "Film Projects"

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Aka. chroma key, and color keying.
Aka. chroma key, and color keying.
[http://en.wikipedia.org/wiki/YUV YUV color space]:
* Y: [http://en.wikipedia.org/wiki/Luma_(video) Luma] - Brightness black-and-white signal
* UV: [http://en.wikipedia.org/wiki/Chrominance Chrominance] (two) - Color signal
[http://en.wikipedia.org/wiki/Chroma_subsampling Chroma subsampling] resolution:
* 4:4:4 (Y:U:V) - full resolution / high bandwidth
* 4:2:0 (Y:U:V) - less resolution / lower bandwidth
* 4:1:1 (Y:U:V) - less resolution / lower bandwidth
[http://cdn3.libsyn.com/macbreak/macbreak20060303-001b-mp4.mov MacBreak part 2] explains and shows how chroma subsampling works.


Quotes:
Quotes:
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* [http://forums.cgsociety.org/showthread.php?s=cf5bcfd0ef189ceb485eec675f99884d&p=2911287#post2911287 CGTalk GreenScreen]
* [http://forums.cgsociety.org/showthread.php?s=cf5bcfd0ef189ceb485eec675f99884d&p=2911287#post2911287 CGTalk GreenScreen]
* [http://www.pcquest.com/content/multimedia/2004/104070101.asp Matte creation in After Effects]
* [http://www.pcquest.com/content/multimedia/2004/104070101.asp PCQuest Matte creation in After Effects]
* [http://www.dvgarage.com/prod/prod.php?prod=dvmatteae&sub=features dvMattePro]
* [http://www.dvgarage.com/prod/prod.php?prod=dvmatteae&sub=features dvGarage dv Matte Pro]
* [http://www.dvcreators.net/discuss/showthread.php?t=7197 Green Screen!]
* [http://www.dvcreators.net/discuss/showthread.php?t=7197 DVCreators Green Screen!]
* [http://forums.macrumors.com/showthread.php?p=1943695 Bluescreen on the cheap?]
* [http://forums.macrumors.com/showthread.php?p=1943695 MacRumors Bluescreen on the cheap?]
* [http://www.computerarts.co.uk/tutorials/3d__and__animation/bluescreen_on_a_budget Bluescreen on a budget]
* [http://www.computerarts.co.uk/tutorials/3d__and__animation/bluescreen_on_a_budget Bluescreen on a budget]
* [http://www.dvguru.com/2006/12/21/tips-for-compositing-dvc-pro-hd-footage/ Tips for compositing DVC Pro HD footage]
* [http://www.dvguru.com/2006/12/21/tips-for-compositing-dvc-pro-hd-footage/ Tips for compositing DVC Pro HD footage]

Revision as of 15:12, 6 April 2008

Blue or Green-screen

Aka. chroma key, and color keying.

YUV color space:

  • Y: Luma - Brightness black-and-white signal
  • UV: Chrominance (two) - Color signal

Chroma subsampling resolution:

  • 4:4:4 (Y:U:V) - full resolution / high bandwidth
  • 4:2:0 (Y:U:V) - less resolution / lower bandwidth
  • 4:1:1 (Y:U:V) - less resolution / lower bandwidth

MacBreak part 2 explains and shows how chroma subsampling works.

Quotes: 

If you can plan your DV shot to have mostly dark subjects (dark hair & clothing) in front 
of a green screen (or bright/blond subjects in front of blue), you can use the color difference 
key to pull a quick core matte, then turn to a luma-based solution to bring out the edge details.

With DV and DVCam, you won't have as much color information per pixel due to compression, so 
good mattes are harder to pull. It ends up looking pretty aliased. Both NTSC and Pal DV formats 
have pretty low sampling (4:1:1 for NTSC and 4:2:0 for Pal).

It was all pixelated and jagged edges. How do u get around this?
The technique that I've heard used most often is that you blur the UV channels (the chromanance 
part of the YUV) then mix that back in with the Y (luminance) and your ready to pull a matte. Do 
just enough blur so the pixelated jagged edges soften. Use that only for pulling the matte. Once 
you've got your matte, go back and use the original footage for applying the matte.

Programs / Plug-ins

  • dvMattePro
  • Keylight
  • Shake (OS X only)
  • Final Cut Pro (OS X only)

Lightning

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