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noise inside what i think is a good key

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craig hellennoise inside what i think is a good key
by on Jul 21, 2010 at 10:07:29 pm

Hey All,

I am working on a full body key, (tricky i know) I think im nearly there but im hitting a bit of a problem with noise.

I get what I think is a good key, in the screen matte mode of keylight im getting a solid white on the subject and decent black round the keyed color.

I tweak all the other settings to get it just right but for some reason I keep getting an annoying ammount of noise on the lower tones of the subject.

I will post up my results tomorrow but for now i have posted up a sample of the raw footage for anyone to take a peek at here: https://www.yousendit.com/download/T1VtNU1La0Q5NVUwTVE9PQ


Any help is appreciated.

I have done a garbage matte on this as well. all shot on dvcam pal

Craig




Co-Director Podchains Ltd
Video Producer / Motion graphics designer http://bexmedia.net


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Rich RamazinskiRe: noise inside what i think is a good key
by on Jul 21, 2010 at 10:52:20 pm

yeah i bet that black shirt has a bit of noise on it!

Craig- are you using keylight? it applies a spill suppression automatically that sometimes i just turn off and do some alternate color correcting to avoid that noise problem.

if you turn View to Intermediate Result, does the noise go away?

check out this post:

http://forums.creativecow.net/thread/2/947502#947577

http://www.richrama.com


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Dave LaRondeRe: noise inside what i think is a good key
by on Jul 21, 2010 at 10:55:27 pm

[craig hellen] "all shot on dvcam pal"

Ugh. DV's just about the worst footage to use for keying. I feel your pain.

But here's a trick that works many times:
  • Add two instances of your footage to the timeline, one above the other. Turn off the lower one.
  • Pull a good-looking key on the top layer, and don't worry about the noise. Just make sure the edges and the interior of the subject look nice and solid.
  • Turn on the lower layer, and use the upper layer as an alpha matte for your footage.
  • If you need Keylight's spill suppression capabilities, you can add it to the lower layer, but be careful not to key anything -- just fiddle with the controls until the chroma key background looks washed out, but doesn't key out.

That oughta do it.

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


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craig hellenRe: noise inside what i think is a good key
by on Jul 22, 2010 at 10:49:36 am

Thanks for the tips both of you! Im pretty much sure that Im on the way to getting it now,

I did forsee the problems with DV dave, but I didnt have some nice dvcpro-hd camera to shoot on.

Out of interest what do you recon to shooting chromakey stuff with a dslr? Better colour space but is the compression even worse to key? Too late for that now but I would like to know for next time :-)

Many thanks again!

Co-Director Podchains Ltd
Video Producer / Motion graphics designer http://bexmedia.net


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Dave LaRondeRe: noise inside what i think is a good key
by on Jul 22, 2010 at 1:08:05 pm

If you have AE 10 (aka CS5), you ought to be good shooting DSLR video. I hate the codecs to which they compress the images, but that's my problem and not yours.

But if you DO NOT have AE 10, you should read this:

Dave's Stock Answer #1:

If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, AVCHD, mp4, mts, m2t, H.261 or H.264 -- you need to convert it to a different codec.

These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.

In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.

I'm a Mac guy, so I like to convert to Quicktime movies in the Animation or PNG codecs; both are lossless. I'll use Apple's Compressor, Adobe Media Encoder or Quicktime Pro to do it.


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


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craig hellenRe: noise inside what i think is a good key
by on Jul 22, 2010 at 4:02:44 pm

thanks dave!

Thats great to know, glad i didnt completely trip into one of your stock answers there!

Many thanks as always

Co-Director Podchains Ltd
Video Producer / Motion graphics designer http://bexmedia.net


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