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DPChallenge Forums >> Tips, Tricks, and Q&A >> In Camera Noise Reduction?
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 07/26/2005 01:50:08 PM · #1
I was just wondering recently, what the benefit of using in-camera noise reduction is if you are shooting in raw. I mean, when I open my RAW file in Photoshop's RAW plugin, it has an option for noise reduction in there also. And if I understand correctly, a RAW file is saved without any camera adjustments. Does that include the noise reduction? Or is that still doing something in-camera, and then I can do it again in Photoshop?

I would greatly appreciate any responses possible.
 07/26/2005 03:48:48 PM · #2
bump

That's a good question. I know that on my 20D the in-camera noise reduction only works on long exposures. But whether or not it is in operation when shooting RAW I don't know.
07/26/2005 04:09:13 PM · #3
For the D70 it applies long-exposure NR for RAW mode as well. I know because I have to wait for the NR cycle a lot at night.

Speaking of in-camera NR, I want to do a test to see how effective it is, and if using Neat Image later can do as good a job, or manual dark-frame subtraction.
 07/26/2005 05:10:46 PM · #4
In camera noise reduction is superior to after-the-fact noise reduction.

The way it works in the 20D is this: If you take a long exposure (1 second or more), then after the exposure is done, the camera closes the shutter, but continues to watch the CCD for the same amount of time. Then it subtracts out the noise that it gets during that 1 second of "darkness".

So, if you take a 1 second exposure, the shutter closes and the CCD runs for another second. If you take a 15 second exposure, then you have a 15 second wait after the shutter closes before your image emerges on the LCD. And so on.

So basically, the camera is just trying to filter out known "noise" in the system.

After the fact, your editor has to try to guess what is noise from what is detail. Any type of noise removal at this stage must also, by necessity, remove detail. The trick is to try to remove just enough noise and leave as much detail as possible behind by analyzing the "pattern" in the noise and removing the patter.

Now, to be fair... even noise in the CCD can land on top of detail. And thus, in-camera noise reduction also removes detail. It's just that, in-camera it's less of a "guess" as to what is noise versus detail.

And yes, even when shooting RAW the "dark frame" subtraction still occurs.

Message edited by author 2005-07-26 17:11:42.
 07/26/2005 05:18:34 PM · #5
Originally posted by traquino98:
(...)And if I understand correctly, a RAW file is saved without any camera adjustments. Does that include the noise reduction?(...)

I would greatly appreciate any responses possible.


Actually RAW mode saves pictures with the possibility to adjust Exposure compensation and White balance after the shot was taken. But some adjustments is still necessary before you take your shot. For exemple, your ISO settings can't be changed.

But that was a good post, I'm glad I've learned just how noise reduction works. Thanks!

Message edited by author 2005-07-26 17:20:34.
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