October 25, 2014, 12:15:12 AM

Author Topic: In-camera noise reduction  (Read 2750 times)

Harv

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In-camera noise reduction
« on: March 13, 2013, 09:09:30 AM »
This question is directed to the technically knowledgeable out there and has to do with in-camera noise reduction settings.  Although I'm shooting with a 1D4, I would guess the same would apply to all models.

In a nutshell, is in-camera noise reduction (assuming it's enabled) applied to RAW files or just to JPEGs?  If it's applied to RAW files (which is all I shoot), have any of you shot RAW with noise reduction disabled, and if so, how were the results?

I tried to do a search here on this topic but was unable to find any information.

Thanks.
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In-camera noise reduction
« on: March 13, 2013, 09:09:30 AM »

neuroanatomist

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Re: In-camera noise reduction
« Reply #1 on: March 13, 2013, 09:54:12 AM »
Long exposure NR (where a dark frame is taken after the exposure and subtracted) is applied to the RAW image.  No other form of in-camera NR is applied to the RAW image.
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Harv

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Re: In-camera noise reduction
« Reply #2 on: March 13, 2013, 10:02:22 AM »
Long exposure NR (where a dark frame is taken after the exposure and subtracted) is applied to the RAW image.  No other form of in-camera NR is applied to the RAW image.

Thanks a lot, Neuro.  I was hoping you might respond.  I suspected that was the case, but could not find any info on the subject.
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eninja

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Re: In-camera noise reduction
« Reply #3 on: March 14, 2013, 11:54:14 PM »
As you said, "No other form of in-camera NR is applied to the RAW"

(I am new in DPP.)

But in DPP, When you convert images from raw,
it will AUTOMATICALLY APPLY Noise Reduction as set in the tool palette.
even without clicking the apply button before hand. Am I right?

Under preference->tool palette tab-> Default Noise Reduction Setting
. When set to Apply Camera Settings,

Can anyone explain how the NR settings is affected, according to Camera Setting?
In this context does Camera settings refer to NR setting inside the camera or does it has more complex algorithm taking ISO and other parameters into account?

mb66energy

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Re: In-camera noise reduction
« Reply #4 on: March 15, 2013, 02:05:22 AM »
Can anyone explain how the NR settings is affected, according to Camera Setting?

There are (at least) two components of noise reduction:
  1 Noise reduction on the sensor raw data +
  2 noise reduction SETTINGS (besides the sensor raw data)
     in the raw files which keep information for DPP etc.

What I deduced from my cameras (40D, S95):

Ad 1:
Long exposure noise reduction exposures a dark frame (shutter closed) with the
same exposure time as the image exposure (e.g. 15 sec exp time means 30 sec
for one exposure process!). The dark frame image is subtracted from
the image frame to remove noise, especially hot pixels (which show signals without
getting light). This affects the sensor raw data.

Ad 2:
Noise reduction settings are stored according to the chosen ISO (and exposure time?)
in the "settings section" of the raw file. These do not affect the sensor raw data but
the development in DPP (etc.).

I haven't found a menu setting to suppress the noise reduction settings for DPP
in my camera.
My procedure:
  Edit one image to set the noise reduction to zero (NR is usually
  applied at base ISO and degrades percepted sharpness!).
  Copy the recipe to the other images of that series.

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Skulker

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Re: In-camera noise reduction
« Reply #5 on: March 15, 2013, 04:27:05 AM »
Long exposure NR (where a dark frame is taken after the exposure and subtracted) is applied to the RAW image.  No other form of in-camera NR is applied to the RAW image.

This is my understanding for how canons work. But I understand some camera makes do include NR effects in the raw file.
If you debate with a fool onlookers can find it VERY difficult to tell the difference.

neuroanatomist

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Re: In-camera noise reduction
« Reply #6 on: March 15, 2013, 06:45:47 AM »
Ok, for the purists out there, let me clarify. The OP asked:

This question is directed to the technically knowledgeable out there and has to do with in-camera noise reduction settings.

The only NR setting (i.e., something that can be changed by the user in the camera's menu options) that results in NR being applied to the RAW file is Long Exposure NR.  No other form of in-camera NR setting is applied to the RAW file.

Better?  ;)

Yes, mapped hot pixels are suppressed before the RAW file is written, I suppose one could call that a form of noise reduction (but also, mapped dead pixels are 'filled in' before the RAW file is written, so if you call the former noise reduction, you should call the latter noise addition, rendering any net effect a random phenomenon dependent on the individual sensor). 

AFAIK, Canon doesn't do anything as egregious as Nikon's 'mode 3' (a median blur filter applied to RAW files on certain cameras with long exposures even with long exp NR set to off, which can only be eliminated if you enable long exp NR then power the camera off during the dark frame acquisition).

Could there be other forms of subtle NR applied to the RAW file, which the user cannot change with settings and are therefore irrelevant except as a matter of academic interest?  Sure.  If you want to go run a bunch of Fourier transforms and investigate, have at it and let us know what you find...
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Re: In-camera noise reduction
« Reply #6 on: March 15, 2013, 06:45:47 AM »

neuroanatomist

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Re: In-camera noise reduction
« Reply #7 on: March 15, 2013, 09:17:46 AM »
I never use DPP, but does it respect in-camera NR settings when developing raw files? It would make sense, but of course, you would then be free to switch it off (or use some other raw developer).

Yes, it does...along with all the other settings (picture style, ALO, etc.), basic lens corrections, etc. 
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Maso

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Re: In-camera noise reduction
« Reply #8 on: March 26, 2013, 01:41:12 AM »
I've been looking for a way to for Lightroom to apply the NR to my imported RAW Files in the same way that DPP does, but presumably this requires NR Devices-specific profiles to be available. I've found a program called, "NeatImage", which appears to do exactly this, but it's another stand-alone application.

Does anybody have a streamlined method for automatically applying the NR to Raw in Lightroom (4.3), either during import or as a post-import bulk process, to approximately (or exactly) match what DPP does automatically?

Thanks...

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Re: In-camera noise reduction
« Reply #9 on: March 26, 2013, 12:42:22 PM »
This question is directed to the technically knowledgeable out there and has to do with in-camera noise reduction settings.  Although I'm shooting with a 1D4, I would guess the same would apply to all models.

In a nutshell, is in-camera noise reduction (assuming it's enabled) applied to RAW files or just to JPEGs?  If it's applied to RAW files (which is all I shoot), have any of you shot RAW with noise reduction disabled, and if so, how were the results?

I tried to do a search here on this topic but was unable to find any information.

Thanks.
Basically, the answer is no, but with qualifications.
 
Besides the long exposure NR mentioned, there is NR built in to the readout circuitry of the sensor, you cannot change this.
 
For Raw images, turning on noise reduction in the menu will set a flag in the raw file and DPP is said to read it and apply NR according to your settings.  Other raw editors do not read the flag and have their own default NR settings.

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Re: In-camera noise reduction
« Reply #9 on: March 26, 2013, 12:42:22 PM »