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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Noise Problems

Frank Mirbach

Frank Mirbach

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Hi guys,

did a test in our backlot to check our Red today. Some shots in partly sunlight, partly shadow. Put that in RedCine and found out that we have
lots of noise in the shadows of the footage. When you dial in some additional exposure in RedCine, it becomes even more obvious, looking like
you´ve shot something on BetaSP with 18dB gain or even more.

What do you think ? Does this mean to send the cam in ?

Frank
 
Jones said:
Hi guys,

did a test in our backlot to check our Red today. Some shots in partly sunlight, partly shadow. Put that in RedCine and found out that we have
lots of noise in the shadows of the footage. When you dial in some additional exposure in RedCine, it becomes even more obvious, looking like
you´ve shot something on BetaSP with 18dB gain or even more.

What do you think ? Does this mean to send the cam in ?

Frank
Click to expand...
do a black calibration,
and some additional exposure of 2 for example means following

320x2x2-------1280 asa

there will be a lot of noise at 1280 asa....

try to add some brightness istead or play with the curves
 
Jones said:
We have
lots of noise in the shadows of the footage.
Click to expand...

There could be a million reasons for this, here are three possibilities:

1. One or two color channels underexposed.
2. Using too much dynamic range.
3. Personal taste and expectations.

By #1, what I mean is that maybe the blue and green channels are well exposed, but red is underexposed (because the light itself just did not have as much red in it). When you white balance, that red is boosted, so the signal-to-noise is worse.

#2 relates to the fact that the RED ONE lets you choose how much dynamic range you want. It does not force you to set your blacks very high. In fact, there is no such thing as "black" in an R3D! It just goes from white to noise. So where you place your black is an artistic choice balancing noise with how much dynamic range you want to use.

Similarly, the only method to increase dynamic range is to underexpose. If that was necessary to prevent clipping highlights, and it caused too much shadow noise, then the scene has too much dynamic range for your taste.
 
Post a 4K TIF so we can see?

Post a 4K TIF so we can see?

REDCODE has some artifacts in the dark areas that look like enlarged noise, 4x the area in the RED and BLUE it seems when you look at underexposed seperations. In my software I have a sharp/soft filter than can blur the red and blue but leave the green sharp, it can make the noise less noticeable.

Most of the time you need more fill light than for shooting newer ECN types, its a digital camera and not all three sensors work at 12bits for all K, so you only have like 10stops which is really +/- 4 stops about to work with.

If you post an 4K TIF image we can see if your noise is abnormal or typical. Do not post a link to a compressed image like JPG, that does not reveal just the REDCODE artifacts.
 
That's part of why everyone is always talking about exposing to the
right because, it can get pretty noisy in the shadows. However, you also need
to keep an eye on clipping highlights, which can happen pretty easily as well.

You can plan to crush your blacks to hide the noise, fill in the shadow areas with big guns or bounces, use noise reduction techniques in post or a combination of all three.

As a D.P., I'd like to learn more about DNR technology and techniques, as it seems a powerful post tool to have available with electronic cameras in general. One can really see the benefits when watching a film like The Curious Case of Benjamin Button. But, that's a huge budget and a 'technically-inclined' director who is pushing for its use. What options are there for the rest of us?

-Michael Jacob Kerber
D.P. / L.A.
 
We preserve the below black noise floor through the compression. We leave it up to you to either clamp it or crush it or use it. But you must do something with that or you may see it. I suggest a gentle black crushing curve or use of "contrast".

Graeme
 
Any good denoiser (like the one from Graeme for Color) can treat color channels independently. If that doesn't suffice, try more sophisticated temporal denoisers, like DE:Noise, CHV Repair Collection or the like.

We had a shoot here recently which the client wanted shot available light at night. Our first tests made the RED look worse than a Sony EX-1 ! After some good denoising and tweaking of curves, they were perfectly happy.

If you want to see what an experienced specialist can do with RED footage, have a look at: http://www.reduser.net/viewtopic.php?f=2&t=190
 
Strange, cut-n-paste changes the address extension. Replace reduser.net with .de , while keeping the rest.
 
Thanks guys ! Our little test was made only in available light, it´s for a documentary we´ll do in May. The shot I´m talking about is extreme in some way, from very bright to pretty dark. The noise is in the darker and mid areas. That shot was mainly made because our EVF was solarizing again and we wanted to make sure the footage was unaffected by this. It was a "quick and dirty" approach. We also did shots not as extreme in terms of contrast, and there also was noise. I just want to make sure the camera is ok and doesn´t have to be send to Red again.

Seems a 4K .tiff is too big to upload here. Any suggestions ?

Frank
 
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