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Old June 7th, 2004, 11:12 AM   #1
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taking away the grain?


I'm in the process of planning my first short film, but have have run into a little problem where my camera is concerned.

Basically, the whole vid will be shot in very low light conditions, and unfortunatly for me with my panasonic gs-30, that means i get a very grainy picture. My question is:

Is there a way of either compensating for this problem in post-prod. or is there a way of eliminating the problem in the fist place.



btw, my film takes place in a field, about 50Meters from an illuminated street. through experimentation, i have found 2 x 20Watt lamps seem to provide a convincing street lamp hue?
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Old June 7th, 2004, 11:34 AM   #2
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Welcome, Ian.

As you might imagine, this topic surfaces relatively frequently here. So if you Search on "grain" you'll see quite a few threads.

But, unfortunately, the short answer is that there's very little you can do to mitigate grainy footage. Some try to add blur to gritty clips hoping to make it less obtrusive, but generally to little avail and almost always to the detriment of the clip.

Making matters worse, if you plan to compress your final movie (ex: for Web viewing) the grain will quickly become an even greater nightmare. Not only will it probably become even more prominent as compression artifacts magnify it, but this false random detail will greatly hamper your ability to compress clips to a more manageable size (for online viewing).

The best advice I can offer is to take every possible measure to avoid the problem. Change your shots. Add some light. Change the time of day. If you're doing a dramatic piece, remember that you can shoot in daylight and manipulate the footage to look like night.

Good luck.
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Old June 7th, 2004, 01:50 PM   #3
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Avoiding grain (video noise)

I'm afraid removing grain from a noisy video picture is something close to impossible. But you can avoid getting a noisy picture when you shoot.
Noise - or grain - is caused by excessive electronic gain applied by the cam in Automatic Aperture (Auto-Iris) when shooting in low light.
The obvious answer to your question would be «Use more light»!
But if you want to preserve night ambiance, you must first switch to MANUAL Iris, and avoid setting the aperture at anything over «OP +6», which means «open iris plus 6dB of gain».
At this aperture, if your scene is still too dark for your taste, think of adding lights instead of pushing gain over +9.

Remember, night scenes can be understood correctly even if just a few highlights are visible. Auto-Iris will ruin your footage by pushing the gain to +18dB or until night resembles daylight!
Norm :)
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Old June 7th, 2004, 03:53 PM   #4
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Hello Ian

There is a way of duplicating the Dual Pixel readout found in Hi End Sony Gear

You will need After FX:-

Create a composition with two copies of your footage on the timeline - one on top of the other

Choose blend mode -screen- for the topmost footage

the next step is most critical - you must horizontally displace the topmost footage by exactly one pixel

the result is an improvement of Signal/Noise ratio of +12db at a minor loss of resolution
John Jay

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Old June 7th, 2004, 04:11 PM   #5
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My approach is to import the video into VirtualDubMod so I have access to the excellent array of free Avisynth noise cancellation plug-ins. Visit http://forum.doom9.org/ for more information, but be warned: there is a lot to learn.
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Old June 8th, 2004, 10:52 AM   #6
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Ian: There's been a lot of excellent information posted already, but I wanted to just throw in that if you were to go with something along the route of blur filters, etc. then you may want to experiment with the Median filter. This would keep the appearance of sharpness better than a blur filter.

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Old June 8th, 2004, 01:00 PM   #7
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Thanks for your help guys, I did'nt expect such a response.

There is alot for me to learn and experiment with here, and as has already been sugested, i shall take a look around the forum for other related topics. I'll give it a go and see what happens (hopfully a film).

Once again, thanks.


EDIT: Err.. just as an after thought, if it turns that i cant satisfacturaly get a good image, would it help if i hired a XL1s (or similar) for a couple of days. or would this still suffer from the same syndrome?
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