Sony A900 noise, dynamic range and noise reduction

[Panopeeper]

I have found the *perceived* noise characteristics of *my* D3x to be really strange: At 1600 it's unbelievably good, more than enough for fashion/portrait use

There is no healthy patient, only incompetent diagnosis.

[eronald]

There is no healthy patient, only incompetent diagnosis.

you're being elliptically cryptic

Edmund

[JamesA]

I'm afraid you are mixing up some issues. Although the raw data of Nikon cameras is not as raw as the Canon raw, and the difference contributes to a lower apparent noise, that is not comparable to the noise reduction carried out by the A900 on the raw data, and even less to the costomary noise reduction.

Just to clarify, you are saying that even at low ISOs, such as 100-400 ISO, you are saying there is some kind of NR being applied in-camera?

[Panopeeper]

you're being elliptically cryptic

That's called crypto-logiC.

(The thing with the diagnosis is an old joke among doctors.)

[Panopeeper]

Just to clarify, you are saying that even at low ISOs, such as 100-400 ISO, you are saying there is some kind of NR being applied in-camera?

Pls read the opening message of this thread; it is about nothing else.

[douglasf13]

Pls read the opening message of this thread; it is about nothing else.

  I'm curious whether it's being applied on-chip in the second NR portion, or in the BIONZ??

[thierrylegros396]

I'm curious whether it's being applied on-chip in the second NR portion, or in the BIONZ??

On chip is possible because it is a CMOS !

Thierry

[Guillermo Luijk]

Euh...

- ease of use through more streamlined workflows,
- better DxOMark results that make the A900 puchasers feel good about their investement
- less apparent noise in low ISO shadows that will prevent people from over-exposing, therefore blowing highlights

Everything is relative Gabor. You are only dissatisfied with the shadows of the A900 because you have found that they could have been closer to your taste (meaning noisy but more detailed). All those users who don't know this are just happy about having clean shadows... See above for some ideas on the value of clean shadows.

Don't get me wrong, I am with you here, noise reduction in camera is not something I find to be a good idea, but I am just trying to put things in perspective.

I agree with you Bernard, you put in perspective the well known fact that many people will be happy without knowing that his wife or her husband is seeing another person, or will pick the blue pill and enjoy eating the fake beefsteak in Matrix the movie. But some other people prefer to know what's really under the hood, that's why I think Gabor's analysis are very valuable.

I also made a list of advantages of all these tests and findings:
- The user has the power to _decide_. To decide if switching on/off camera's NR. To decide if purchasing or not a camera where NR cannot be switched off.
- Camera vendors can find out not everyone out there are just followers willing to buy any new camera on the market that _seems_ to perform better than others, so maybe they finally concentrate on making cameras that _do perform_ better than others.
- Sites like DxO Mark, whose RAW analysis are the best found on any public site, can admit their quality measuring criteria is weak against camera vendor RAW tricks, and mend this.
...

[Panopeeper]

I'm curious whether it's being applied on-chip in the second NR portion, or in the BIONZ??

The on-chip noise reduction is rather noise avoidance. It cares for single pixels, it does not create blobs.

Moreover, the noise reduction we can see here is selective: in ISO 1600 (and above, I guess) it can be turned on to one of three levels or off. The signs of that actuion are identical to those observable in ine lower ISO shots, but not selectable.

[ziocan]

There is no healthy patient, only incompetent diagnosis.

and there are plenty of doctors who do not listen.

[douglasf13]

  FWIW, Iliah Borg has weighed in on this issue a bit.  Maybe you could get involved in this thread, Gabor:

 :link to Iliah's comments:

[Guillermo Luijk]

Gabor, following the use of FFT to find traces of noise reduction made by Emil Martinec here, I calculated the FFT distribution of noise found in the cup of post #19:



There is no evidence, from the FFT perspective, that any noise reduction has been applied to the RAW data in the 'OFF' setting. So would it be logical that NR is applied to low ISOs from 100 to 800 in the 'OFF' setting?

On the other side for any other setting a clear spatial pattern arises in the FFT (in fact is the same pattern for 'LOW', 'MEDIUM' and 'HIGH', just with different amplitudes) that makes think of some noise reduction algorithm based not only in adjacent pixels but also pixels at greater distances.

Perhaps Emil can give his interpretation.

BR

[ejmartin]

Gabor, following the use of FFT to find traces of noise reduction made by Emil Martinec here, I calculated the FFT distribution of noise found in the cup of post #19:

http://img24.imageshack.us/img24/6760/compd.jpg

There is no evidence, from the FFT perspective, that any noise reduction has been applied to the RAW data in the 'OFF' setting. So would it be logical that NR is applied to low ISOs from 100 to 800 in the 'OFF' setting?

On the other side for any other setting a clear spatial pattern arises in the FFT (in fact is the same pattern for 'LOW', 'MEDIUM' and 'HIGH', just with different amplitudes) that makes think of some noise reduction algorithm based not only in adjacent pixels but also pixels at greater distances.

Perhaps Emil can give his interpretation.

BR

The uniform appearance of the FT of the image with NR off supports the notion that no noise reduction is being used.  It's not a guarantee, more the other way around -- if one *does* see the appearance of a pattern, with the noise power reduced at high spatial frequency, then that is strong evidence that there *is* NR taking place.  (High spatial frequency is located at the edges of the FT image; reduced noise power at high frequency means that the speckling is darker there.)  It could be that there is still NR being done even when the speckling is uniform, but that it's of a more subtle form than a simple finite range spatial filter.

Iliah seems to think that the issue is black clipping:

http://forums.dpreview.com/forums/read.asp...essage=31285521

Why oh why don't camera manufacturers offset their data so that the noise spectrum is not corrupted?  

[Panopeeper]

There is no evidence, from the FFT perspective, that any noise reduction has been applied to the RAW data in the 'OFF' setting. So would it be logical that NR is applied to low ISOs from 100 to 800 in the 'OFF' setting?

Actually, this is what I stated in the initial post: the NR setting does apply to ISO 1600 (and I guess higher, but I did not care for that), but it has no effect at lower ISOs; some NR *always* takes place.

On the other side for any other setting a clear spatial pattern arises in the FFT (in fact is the same pattern for 'LOW', 'MEDIUM' and 'HIGH', just with different amplitudes) that makes think of some noise reduction algorithm based not only in adjacent pixels but also pixels at greater distances

The actual noise reduction is very primitive. I am working on the demonstration (in fact on a dozen demonstrations, I have created already hundreds of captures). The result of the NR is the reduction of the number of levels and "blobs" of pixels in the same level.

The attachments in my post #38 should be clear enough, I don't see much room for speculations.

[douglasf13]

Actually, this is what I stated in the initial post: the NR setting does apply to ISO 1600 (and I guess higher, but I did not care for that), but it has no effect at lower ISOs; some NR *always* takes place.


The actual noise reduction is very primitive. I am working on the demonstration (in fact on a dozen demonstrations, I have created already hundreds of captures). The result of the NR is the reduction of the number of levels and "blobs" of pixels in the same level.

The attachments in my post #38 should be clear enough, I don't see much room for speculations.

 What to you think in regards to Iliah's black clipping explanation?

[JamesA]

I have found the *perceived* noise characteristics of *my* D3x to be really strange: At 1600 it's unbelievably good, more than enough for fashion/portrait use. After 1600 it's like going off a cliff.

Edmund

Part of it is the fact the noise in the D3x that is visible is so damn attractive compared to various other cameras.

[Panopeeper]

What to you think in regards to Iliah's black clipping explanation?

It is NOT black cipping.

[Guillermo Luijk]

Part of it is the fact the noise in the D3x that is visible is so damn attractive compared to various other cameras.

wow! what does make D3X's noise so attractive? I thought digital noise was just a gaussian distribution on any camera sensor, with no spatial structure and which amplitude solely depends on the number of converted photons and the ISO gain setting.

[douglasf13]

It is NOT black cipping.

  Could explain a bit more in detail?  Iliah wrote some pretty interesting stuff in that thread.

[Panopeeper]

Could explain a bit more in detail?  Iliah wrote some pretty interesting stuff in that thread.

I am working on it. It is not a simple, straightforward issue; I am demonstrating it through a whole bunch of observations, all heavy duty pixel peeping.