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Author Topic: Sony A900 noise, dynamic range and noise reduction  (Read 63237 times)
Panopeeper
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« Reply #20 on: March 09, 2009, 11:39:08 PM »
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Regarding the blotches: this requires a bit pixel peeping. The attached captures show the blue channel from the coffee cup, one pixel level at a time. It starts with 129, for everything lower becomes null. Note: this is ISO 800, NR Off, i.e. this is the forced NR. These groups of pixels in the same level are characteristic to the forced NR of the A700 and A900, they have nothing to do with the texture of the cup, they appear everywhere the same way.

The last capture shots the histogram on the side of the cup; notwworthy is the difference between the red/blue and the green: the red and blue are much more "shrunk" around 128, thereby "compressing" the levels, making the noise lower and the appearance darker.

The same is happening in the red channel, but the green is much different, even though it does not remain untouched. This is not restricted to the levels so close to 128, the same happens somewhat higher as well (the pixel values of the ninth and higher stops are between 128 and 143).

(Let's try to get back the attachements)
« Last Edit: March 10, 2009, 12:42:26 AM by Panopeeper » Logged

Gabor
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« Reply #21 on: March 10, 2009, 12:01:55 AM »
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Quote from: Panopeeper
Partonization is a mild form of terror; one can not over-react to it.

You are over-reacting...  

Quote from: Panopeeper
As to the % of image quality: do you mean that one should rescind a percentage of the hardware capabilities for .. for... WHAT in exchange? Perhaps it is an intentional degradation in exchange for the low price? Perhaps an A910 will be released for $200 more, the same camera but without forced NR?

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

Quote from: Panopeeper
Now, this is the point. A compromise between WHAT? A compromise presumes two or more sides of an issue; something for something. What exactly is the advantage of doing a premature noise reduction without my asking, when doing that later, at my discretion is *at least* as good? What other consideration is here beside image quality? Do Sony collect the stolen pixel levels and sell them someone?

The sensor has certain capabilities, which can NOT be enhanced, only degraded the way Sony chose to go. I am not complaining about the sensor not being good enough, but about the firmware intervening (trespassing) in the process of developing the image. What is happening is cheeting with the appearance on the cost of real quality.

There is absolutely no compromise here, only sacrifice, due to some misguided decision, just like with the A700. I wonder if Sony will do this with every new model, waiting until some customer groups are yelling loud enough.

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.

Cheers,
Bernard
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A few images online here!
mike.online
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« Reply #22 on: March 10, 2009, 12:09:14 AM »
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without getting too technical, how are you getting the raw data to compare the true DR to the augmented DR for the a900 ?


also, if the a900 makes too many assumptions in their processing algorithms, why not just hack their firmware? Naturally this would be a real pain in the ass but if you connect with a good enough community of developers (using git or something of that nature), you could make something to accomplish zero change in the raw data, no?

I'm surprised that nobody hacks camera firmware so far that I've seen... It happens with so many other devices, why not cameras?

I'm not a firmware hacker for any device, but I have a sufficiently deep knowledge of CS to begin to pick it up.

EDIT: a google came with this;
http://chdk.wikia.com/wiki/CHDK - Canon hacking wiki
http://www.camerahacker.com/ - enthusiast site
« Last Edit: March 10, 2009, 12:12:59 AM by mike.online » Logged

Panopeeper
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« Reply #23 on: March 10, 2009, 12:26:45 AM »
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Quote from: mike.online
without getting too technical, how are you getting the raw data to compare the true DR to the augmented DR for the a900 ?
I am not, for I can not. However, if Erik manages to make shots with his A900 and with a Canon at the same time, then I can relate the intensities.

Quote
if the a900 makes too many assumptions in their processing algorithms, why not just hack their firmware?
Well, why not? However, the effort is lost when the next firmware version is released and you need it.

There is a firmware hacker/enhancer community, but they are dealing only with certain processors and with certain cameras. Camera makers are not keen to publish any internals.
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Gabor
Panopeeper
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« Reply #24 on: March 10, 2009, 12:39:24 AM »
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Bernard, the issue is not so small. At first sight it might appear that this affects only the very-very dark regions, but this is not so: even a medium dark area can have one or two very low component. For example one of the greenish (not pure green) patch on the color checker sheet Erik has been photographing contains greens in the sixth stop and blues in the ninth (or it appears in the ninths). The blues are blotchy; this may make the result blotchy.
Particularly, if one channel gets pushed up due to WB, it can affect much brighter areas as well. Why do you think Sony stopped the unwanted NR with the A700?

In some cases these pixel groups (the blotches) are like perfect mosaics; the pixels of two levels occupy over 90% of the area. Sometimes the groups are not in adjacent pixel levels; this makes their blotchiness particularly strong, when carrying over in the RGB value.
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Gabor
mike.online
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« Reply #25 on: March 10, 2009, 12:49:16 AM »
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Quote from: Panopeeper
I am not, for I can not. However, if Erik manages to make shots with his A900 and with a Canon at the same time, then I can relate the intensities.


so then you are speculating that a 'true' raw file would have better DR than a NR off file, based on the knowledge of the differences between NR on and NR off and extrapolating because any onboard raw pre-processing must make it- the same or- worse than the original data, yes?

am i missing a crucial step?
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Panopeeper
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« Reply #26 on: March 10, 2009, 01:11:42 AM »
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Quote from: mike.online
so then you are speculating that a 'true' raw file would have better DR than a NR off file
1. The dynamic range of the camera is determined by the sensor; that can not be changed.

2. Presently the noise reduction (even with NR Off) causes dark areas appear even darker; this makes the impression, that the DR is greater than it is in fact. This is reinforced by measurements, which are based on the intensity after this noise reduction.

I too am measuring the noise in conjunction with the average pixel intensity on a selected patch; if that pixel intensity is artificially lowered, then the measured standard deviations get assigned to deeper shadows then it should be, i.e. the DR appears greater.
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Gabor
mike.online
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« Reply #27 on: March 10, 2009, 01:22:56 AM »
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Quote from: Panopeeper
1. The dynamic range of the camera is determined by the sensor; that can not be changed.

2. Presently the noise reduction (even with NR Off) causes dark areas appear even darker; this makes the impression, that the DR is greater than it is in fact. This is reinforced by measurements, which are based on the intensity after this noise reduction.

I too am measuring the noise in conjunction with the average pixel intensity on a selected patch; if that pixel intensity is artificially lowered, then the measured standard deviations get assigned to deeper shadows then it should be, i.e. the DR appears greater.


check. thanks for the methodology clarification . I'll be interested to read your report, once compiled
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dwdallam
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« Reply #28 on: March 10, 2009, 03:10:24 AM »
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It seems that Sony is guilty of what we called "tuning" their hardware to get a specific reaction from uncritical test sites. For example, Card manufacturers use to send their video cards to specific sites, knowing what software/hardware they used to analyze their cards. They would "tune" the card to perform extremely well on the tests. That latest about one quarter because the test sites caught on really fast to what was happening. That's why they always test synthetic and then back that up with ever revolving real time FPS analysis running each new iteration of game's built in FPS (frames per second) Demo. This is what Gabor is doing, backing up the "test" files by doing his own analysis at a level that cannot be faked.

And even though some people might think "So what, it looks really good, it looks like really high DR, and it looks like really low noise, so who cares?" And the answer is that if you need to manipulate an image that is noise reduced to a point of being unmanipulated, you lose the ability to further manipulate the image to your specific needs. And yeah Sony could put in a switch easily that allowed one to turn off noise reduction completely, but then everyone would be saying, Not that great noise control and DR but pretty good." And then all the people who ran out and bought the A900 might have bought the 5DMKII instead. That's a marketing decision, one that limits our control over our photography for sure.
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ErikKaffehr
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« Reply #29 on: March 10, 2009, 11:24:43 AM »
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Hi,

Hacking is not easy, you know...

Best regards
Erik

Quote from: mike.online
without getting too technical, how are you getting the raw data to compare the true DR to the augmented DR for the a900 ?


also, if the a900 makes too many assumptions in their processing algorithms, why not just hack their firmware? Naturally this would be a real pain in the ass but if you connect with a good enough community of developers (using git or something of that nature), you could make something to accomplish zero change in the raw data, no?

I'm surprised that nobody hacks camera firmware so far that I've seen... It happens with so many other devices, why not cameras?

I'm not a firmware hacker for any device, but I have a sufficiently deep knowledge of CS to begin to pick it up.

EDIT: a google came with this;
http://chdk.wikia.com/wiki/CHDK - Canon hacking wiki
http://www.camerahacker.com/ - enthusiast site
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ErikKaffehr
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« Reply #30 on: March 10, 2009, 11:57:40 AM »
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Hi,

There is certainly some tuning in order to get good reviews. Almost all reviews are done on JPEGs, however, so this issue with NR on raws is not necessarily related to tuning for reviews. The blotchiness reported by Panopeeper does also effect high ISO JPEGS, however.

DPReview had never given good marks for noise to any Sony or Minolta camera, by the way, so would Sony have a strategi to do excessive noise reduction it certainly does not work with DPReview, nor does it work with DxO-mark.

Another way to see it is that without the A900 there would not be any 5DII. Canon would have no reason to release the 5DII unless there was competition. Would Nikon has released the D3x without the A900 and the 5DII being around no one would complain about the price.

Aside from that, the Sony A900 is essentially doing what it is supposed to do, nameley taking pictures and it is quite good at it. It is not really a high ISO camera nor intended for sports. As a landscape camera it works very well.

The noise reduction we are discussing is not a software solution to my best understanding but something done on chip,not necessarily in softfware but probable having to do with preamps before the ADC. That may be related that it cannot be shut off completely. Sony has not been secretive about this in any way, it has been published in their description of the sensor chip.

If you check DxO-mark the 1DsIII and the 5DII are in the same league as the A900 (within some decimals). The Nikon D3x is significantly better. Panopeeper is somewhat sceptical about the claims for the D3x, but we cannot now for shure unless DxO makes their "raw" images public or someone having a D3x makes the images Panopeeper needs for his evaluations.

Best regards
Erik


Quote from: dwdallam
It seems that Sony is guilty of what we called "tuning" their hardware to get a specific reaction from uncritical test sites. For example, Card manufacturers use to send their video cards to specific sites, knowing what software/hardware they used to analyze their cards. They would "tune" the card to perform extremely well on the tests. That latest about one quarter because the test sites caught on really fast to what was happening. That's why they always test synthetic and then back that up with ever revolving real time FPS analysis running each new iteration of game's built in FPS (frames per second) Demo. This is what Gabor is doing, backing up the "test" files by doing his own analysis at a level that cannot be faked.

And even though some people might think "So what, it looks really good, it looks like really high DR, and it looks like really low noise, so who cares?" And the answer is that if you need to manipulate an image that is noise reduced to a point of being unmanipulated, you lose the ability to further manipulate the image to your specific needs. And yeah Sony could put in a switch easily that allowed one to turn off noise reduction completely, but then everyone would be saying, Not that great noise control and DR but pretty good." And then all the people who ran out and bought the A900 might have bought the 5DMKII instead. That's a marketing decision, one that limits our control over our photography for sure.
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ErikKaffehr
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« Reply #31 on: March 10, 2009, 12:21:52 PM »
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Hi!

I don't really feeleasy about this. The problem is that I can probably borrow a Canon, but I probably need to change a lot of settings, which I don't know how to do, worse is that the owner probably wants it back in the same shape as it was before. But I may be able to engage a Canon owner in this project.

Best regards
Erik

Quote from: Panopeeper
I am not, for I can not. However, if Erik manages to make shots with his A900 and with a Canon at the same time, then I can relate the intensities.
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douglasf13
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« Reply #32 on: March 10, 2009, 12:32:41 PM »
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  I am duplicating this post from dyxum.

"Interesting thread. I've got a couple of comments/questions.

[Kiklop,] am I correct in remembering that Sony has been using non-linear RAW data as far back as the A100?

Secondly, I take DxO Mark, like all reviews, with a grain of salt. That being said, it seems strange to me that in light of their brand new A700 review, which goes into some detail about NR on the green channel prior to firmware V4, DxO mark wouldn't notice NR on the blue/red channel in the A700/A900 if it existed. Panopeeper, I have a VERY limited knowledge on your raw analyzer and how it works, so I'm wondering why there is this discrepancy?? Thanks.


Dxo Mark A700 NR article
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ErikKaffehr
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« Reply #33 on: March 10, 2009, 01:39:24 PM »
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Hi,

What I gather is that Sony does a different kind of noise reduction than DxO is checking for. DxO is checking for spatial noise reduction, that is some kind of mixing the signal from a center pixel with surrounding pixels, the kind of noise reduction Panopeeper has detected is more on the signal itself.

"2. The noise reduction affects mainly the red and the blue channels, much less the green. This is a very primitive noise reduction; it simply eliminates some pixel levels in the affected areas.

3. Due to the nature of this noise reduction, the very dark, noise reduced areas become darker. The consequence is, that not only the visual appearance but the noise measurement too indicates not only lower noise that it would be without NR, but that in deeper shadow, suggesting a greater dynamic range."

From some of the writings I have seen from Sony may indicate that this design was chosen so the chip would cooperate well with the DRO (Dynamic Rnage Optimizer) that brightens up dark parts.

Best regards
Erik



Quote from: douglasf13
I am duplicating this post from dyxum.

"Interesting thread. I've got a couple of comments/questions.

[Kiklop,] am I correct in remembering that Sony has been using non-linear RAW data as far back as the A100?

Secondly, I take DxO Mark, like all reviews, with a grain of salt. That being said, it seems strange to me that in light of their brand new A700 review, which goes into some detail about NR on the green channel prior to firmware V4, DxO mark wouldn't notice NR on the blue/red channel in the A700/A900 if it existed. Panopeeper, I have a VERY limited knowledge on your raw analyzer and how it works, so I'm wondering why there is this discrepancy?? Thanks.


Dxo Mark A700 NR article
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Panopeeper
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« Reply #34 on: March 10, 2009, 02:05:11 PM »
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Quote from: ErikKaffehr
The noise reduction we are discussing is not a software solution to my best understanding but something done on chip,not necessarily in softfware but probable having to do with preamps before the ADC
The on-chip noise reduction is a different class (it should be called "noise avoidance"). However, that is single pixel oriented and never becomes apparent on the image.

The technology is described here (on the "public level"): http://usa.canon.com/uploadedimages/FCK/Im...non_CMOS_WP.pdf
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Gabor
douglasf13
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« Reply #35 on: March 10, 2009, 02:18:55 PM »
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Could the second pass of sensor NR illustrated in this graph be the possible culprit?  Much has been made by Sony that they are adding on-chip NR to both the analog and post ADC digital signal, but this is all done on-chip, due to the EXMOR ADC design being on-chip. I'm curious if the D3x differs in 12bit mode.

« Last Edit: March 10, 2009, 02:21:46 PM by douglasf13 » Logged
Panopeeper
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« Reply #36 on: March 10, 2009, 02:24:19 PM »
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Quote from: douglasf13
That being said, it seems strange to me that in light of their brand new A700 review, which goes into some detail about NR on the green channel prior to firmware V4, DxO mark wouldn't notice NR on the blue/red channel in the A700/A900 if it existed
I have a much smaller "raw base" (raw images files) with the A700 than with the A900; particularly, the Imaging Resource images are not underexposed. Anyway, I have not seen any sign of THAT kind of noise reduction, not even in the darkest regions, what I see in the A900 images. This is immediately visible already on the histograms; the A900 fine histograms proudly display the signs of manipulation (the first one is A700 ISO 100 firmware version 3, the second is A900, ISO 100):

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Gabor
Panopeeper
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« Reply #37 on: March 10, 2009, 02:58:14 PM »
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Quote from: douglasf13
Could the second pass of sensor NR illustrated in this graph be the possible culprit?
This is really interesting, but too superficial (not as if I would understand it if it dealt with hardware measures). The question is if it could cause the blobs, the tight groups of pixels with the same value.

Thzere is one consideration against that, and for software (firmware) manipulation: the effect of NR with ISO 1600, where it is selectable, is the same as what is happening in ISO 100-800, but the degree depends on the level of NR. I posted captures with the "involuntary" blobs above. The followings are from ISO 1600, NR High; the blobs have the clearest appearance here; with lower level NR it is becoming like what I posted above. The histograms of the darkest patch on the color checker too show the effect of increasing noise reduction: the levels get "pushed together" (the file names in the top white field in the capture indicate the level of NR).


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Gabor
Plekto
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« Reply #38 on: March 10, 2009, 05:21:06 PM »
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Quote
3. Due to the nature of this noise reduction, the very dark, noise reduced areas become darker. The consequence is, that not only the visual appearance but the noise measurement too indicates not only lower noise that it would be without NR, but that in deeper shadow, suggesting a greater dynamic range."

If this is anything like typical LCD displays, a darker black level isn't necessarily a bad thing.  I suspect Sony has purposely tweaked the A900 towards landscape and lower ISO uses.  After all, this is what most of the people who would buy the camera would use it for.   For $2500, it's a very inexpensive 2nd place to the Nikon.  I'd be happy to own one.  

It's obviously using a different method of NR than you usually find.  I've seen the raw files from the A900, and honestly, for the price, it's not a bad way of doing NR, IMO.  Whatever they are doing seems to be good enough.
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eronald
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« Reply #39 on: March 11, 2009, 04:30:43 PM »
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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
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