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Noise in clothing

Posted: Sun, 15th Nov 2009, 8:32pm

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martinvb

Force: 1020 | Joined: 16th Jan 2007 | Posts: 22

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Hey people,

Whilst the Star Trek fan production of my friends and me doing its best to keep on improving (today ordered a new 3x7m green screen: yeeey), there is a particular thing which is bothering me a bit. So I hope there are some smart minds over here who can help providing insights.

One of us spend most of his free time this year sewing costumes 'till deep in the night - every guy is entitled to have his own hobby... - which consist of one half black, one half gray and one half department colors. The darker part of the costumes produce a lot of noise/grain. I really like to get rid of it! Anyone an idea?

We use a Canon HV20 camera, 4x300W key, 2x300W fill and 2x300W back. In a classroom.

To give you an idea where I'm talking about, I've put a sample online containing parts of raw material with the composed result.

www.martinvanbuuren.nl/meuk/NoiseInClothing.wmv (Warning: Contains massive spoilers of our episode Choices Part Two)


Yours, and thanks in advance!

~~~Mart
Posted: Sun, 15th Nov 2009, 9:54pm

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spydurhank

Force: 1956 | Joined: 24th Jun 2008 | Posts: 1357

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Wow that looks really good.

Some of the shots look like they just need a bit more lighting and that should get rid of that noise. I may be wrong but that's what happens to me if I don't light the subjects properly.

Is the noise there when you export out from your NLE and into Visionlab?
What format are you using for viewing on the web?
Posted: Mon, 16th Nov 2009, 2:27am

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Axeman

Force: 17995 | Joined: 20th Jan 2002 | Posts: 6124

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SuperUser

Make sure the digital gain on your camera is turned OFF (0db). Though I don't notice the grain jumping out at me as a major problem.

A lot of the lighting does look a bit flat, more lighting all round, and especially the Key, could also help.
Posted: Mon, 16th Nov 2009, 4:01am

Post 4 of 7

spydurhank

Force: 1956 | Joined: 24th Jun 2008 | Posts: 1357

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This work around is only if you can't re-shoot your scenes with better lighting for whatever reason...

In Visionlab...

1. Key out your footage.
2. Duplicate it.
3. Add a Gaussian blur filter to the duplicate layer. This will blur out
those errant pixels but also blur out the rest of the footage. Not
to worry. The next step will remedy that.
4. Add a transparency filter to the duplicate layer and turn it down to
50% or lower or to wherever you feel necessary. This will allow the
original layer to be visible.

You should notice a "softness" to your footage which will get rid of the noise. Play around with the Gaussian blur filter and the transparency filter till you get the desired effect.

Alternately you could skip the duplicate layer part and add a grade object with the above filters and apply an object mask and link it to the green screen "actor" footage so that it only affects that footage, using masks... you can further isolate the effect so that it only affects the actors costumes by drawing masks around their heads, hands, any visible skin... That would take a ton of work though but it would sure get rid of that noise and grain.

Good luck and I hope this helped.
Posted: Mon, 16th Nov 2009, 10:07am

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Simon K Jones

Force: 27955 | Joined: 1st Jan 2002 | Posts: 11683

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FXhome Team Member

Grain and noise don't have anything to do with the clothing, it's due to a lack of light in your shots which is forcing you to push the camera further than it wants to go. Light your shots more, so that you can dial down the exposure on the HV20, and your blacks will become properly black rather than noisy.
Posted: Mon, 16th Nov 2009, 4:22pm

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martinvb

Force: 1020 | Joined: 16th Jan 2007 | Posts: 22

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Hey guys,

So many thanks for the great response! I've googled on controlling the gain on the HV20, but it seems to be quite sophisticated to handle on this camera. I will try to master it, and reduce the exposure on the camera itself.

As for lights. I'll move more lights to the front, so we have more keylight on the actors. The problem is that we dare not to use more lights, since we might melt a fuse doing so (3000W is the maximum we can use). We also might get bright spots on the actors faces, but we can correct this by applying more theatrical powder and hair spray on them (and probably the reduction on the exposure will do some work).

I prefer a hardware solution over software, since it adds a major load on the post production - considering all our episodes are filmed before a green screen. Perhaps I have too high demands... But isn't that what you get after watching the same scene over and over and over again? wink

Thanks again.

Yours,

~~~Martin.
PS. Oh, for the ones interested, here a link to our download section where you can watch the episodes made.
PPS. To give an answer to Frank's question: From Sony Vegas we render uncompressed avi which cannot be played with VLC because of the bitrate, and from Visionlab we render in PNG-sequences. Final renders are in XVID-AVI and WMV9.
Posted: Mon, 16th Nov 2009, 8:35pm

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Axeman

Force: 17995 | Joined: 20th Jan 2002 | Posts: 6124

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SuperUser

If you can't add more lights, you might try moving the lights you have a bit closer, and adding some diffusion or adjusting the diffusion on them to avoid hotspots.