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Author Topic: What about 36MP DSLRs?  (Read 48673 times)

hjulenissen

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Re: What about 36MP DSLRs?
« Reply #60 on: December 25, 2011, 06:53:35 pm »

Please read my other quotes, you are out of subject which is (was) if highlight DR exists or not, this doesn't have to do with Raw dada being linear but whether the linearization comes from an A/D conversion of an S-slope, which it is! Regards, Theodoros. www.fotometria.gr
Since it seems that many readers have problems understanding what you are trying to say:
Do you believe that the signals found in a raw file tends to be a linear representation of the number of photons hitting the sensor, limited by noise and saturation? What component do you believe is carrying out linearization? Where does an s-curve ever come into relevance between the scene and the raw-files that my Canon DSLR generates?

-h
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jeremypayne

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Re: What about 36MP DSLRs?
« Reply #61 on: December 25, 2011, 06:56:13 pm »

Please read my other quotes, you are out of subject which is (was) if highlight DR exists or not, this doesn't have to do with Raw dada being linear but whether the linearization comes from an A/D conversion of an S-slope, which it is! Regards, Theodoros. www.fotometria.gr

Ok.  Be clear.

Where is this "s-slope" in RAW digital capture?  What does "highlight DR" mean in the context of RAW digital capture?

You seem to be claiming that there is an 's-slope' in the analog signal that is removed by the ADC.  Is that your claim?
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #62 on: December 26, 2011, 03:02:59 pm »

Ok.  Be clear.

Where is this "s-slope" in RAW digital capture?  What does "highlight DR" mean in the context of RAW digital capture?

You seem to be claiming that there is an 's-slope' in the analog signal that is removed by the ADC.  Is that your claim?
What?  ??? s-slope removed(!!) by the ...ADC ?  :D Good Lord. Theodoros. www.fotometria.gr
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hjulenissen

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Re: What about 36MP DSLRs?
« Reply #63 on: December 26, 2011, 05:16:27 pm »

What?  ??? s-slope removed(!!) by the ...ADC ?  :D Good Lord. Theodoros. www.fotometria.gr
Is it your intent to confuse the reader? If not, might I suggest that you calmly and thoroughly answer the unaswered questions that have been put forth to you.

-h
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #64 on: December 26, 2011, 05:43:18 pm »

Is it your intent to confuse the reader? If not, might I suggest that you calmly and thoroughly answer the unaswered questions that have been put forth to you.

-h
But I have, look at number 53 up there! There are some people that think that our eye sees linearly, NO IT DOESN'T, it sees (the brain) using S-slope conversion. The raw data (try to) linearize the scene the way that humans see it, not by the linear light that truly exists in the world, hense the data output is a linearized S-slope, hense highlight DR does exist. Because the data is linear, it doesn't mean that the light we see recorded in them is linear! Regards, Theodoros. www.fotometria.gr
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bjanes

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Re: What about 36MP DSLRs?
« Reply #65 on: December 26, 2011, 06:28:09 pm »

But I have, look at number 53 up there! There are some people that think that our eye sees linearly, NO IT DOESN'T, it sees (the brain) using S-slope conversion. The raw data (try to) linearize the scene the way that humans see it, not by the linear light that truly exists in the world, hense the data output is a linearized S-slope, hense highlight DR does exist. Because the data is linear, it doesn't mean that the light we see recorded in them is linear! Regards, Theodoros. www.fotometria.gr

If the captured image is to reproduce the scene, it must be scene referred--no curve applied. The human visual response (L*) is approximately cube root. If you applied this response to the data and then the output were viewed by a human, the visual response function would have been applied twice.

The output written to the raw file is linear, but the data may be gamma encoded and an S curve applied by the raw converter. The concept of highlight headroom may apply to such altered data, but not to the linear data of the raw file. Even though our working spaces are gamma encoded for perceptual uniformity with editing, the inverse gamma function is applied when the data are printed or sent to the screen.

Regards,

Bill
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #66 on: December 26, 2011, 07:29:11 pm »

If the captured image is to reproduce the scene, it must be scene referred--no curve applied. The human visual response (L*) is approximately cube root. If you applied this response to the data and then the output were viewed by a human, the visual response function would have been applied twice.

The output written to the raw file is linear, but the data may be gamma encoded and an S curve applied by the raw converter. The concept of highlight headroom may apply to such altered data, but not to the linear data of the raw file. Even though our working spaces are gamma encoded for perceptual uniformity with editing, the inverse gamma function is applied when the data are printed or sent to the screen.

Regards,

Bill
Bill, the human vision (like S-slope) does have a linear part! Hense there is no chance to convert something twice, at least not if after the first conversion it falls in the linear part (or most of it). Anyway, this is a photo thread and although scientific approaches are interesting, we care about the photographic result and in this forum we look how pixel density affects our photography. To a photographer a raw file has a meaning only in what it shows to him on his monitor when he opens it and the highlight DR that he sees (which I am glad you confirmed), varies or has different latitude from sensor to sensor. Its called highlight  DR because its on a curve that extends from a linear part and hence underexposing to preserve it, a)helps less than it should, b) squeezes the linear part of the picture more or much more than it affects the highlights which can turn an image into a mess! Thats why I don't like small pixels and I believe that progress in resolution should be sensible, surely tech advancement helps to preserve characteristics and improve resolution, but for most photographers (I hope) "preserve" is not enough, sensors must improve further in highlight DR and noise. Then we can look at resolution. Happy new year, Theodoros. www.fotometria.gr
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hjulenissen

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Re: What about 36MP DSLRs?
« Reply #67 on: December 27, 2011, 12:59:26 pm »

...The raw data (try to) linearize the scene the way that humans see it, not by the linear light that truly exists in the world, hense the data output is a linearized S-slope, hense highlight DR does exist. Because the data is linear, it doesn't mean that the light we see recorded in them is linear! ...
So the answer to my question below is "yes"?
...Do you believe that the signals found in a raw file tends to be a linear representation of the number of photons hitting the sensor, limited by noise and saturation? ...
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #68 on: December 27, 2011, 04:46:58 pm »

So the answer to my question below is "yes"?
The question shouldn't be on what the sensor does but whether some pixels are directed to subtract some of the photons that hit them or some others are directed to amplify the light received (with noise of course). Can I please know your real name and occupation? I 'd like to know who I am talking with... and can you direct me to see some of your photography in the web? Theodoros. www.fotometria.gr
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hjulenissen

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Re: What about 36MP DSLRs?
« Reply #69 on: December 27, 2011, 05:00:59 pm »

The question shouldn't be on what the sensor does but whether some pixels are directed to subtract some of the photons that hit them or some others are directed to amplify the light received (with noise of course).
If you don't want to tell us what you are claiming, can you please stop claiming that digital raw files have s-curves, shoulders, or similar things?
Quote
Can I please know your real name and occupation? I 'd like to know who I am talking with...
I am sorry, no.
Quote
and can you direct me to see some of your photography in the web? Theodoros. www.fotometria.gr
Sure:
http://www.luminous-landscape.com/forum/index.php?topic=57543.0

-h
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hjulenissen

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Re: What about 36MP DSLRs?
« Reply #70 on: December 27, 2011, 05:08:03 pm »

Anyway, this is a photo thread and although scientific approaches are interesting, we care about the photographic result and in this forum we look how pixel density affects our photography.
Some people care about the scientific side of things, others don't. I think that no-one should dictate how others approach their hobby or occupation.
Quote
To a photographer a raw file has a meaning only in what it shows to him on his monitor when he opens it and the highlight DR that he sees
One could equally say that a true photographer never will discuss battery life, as it won't appear as an artifact in her images. But for many photographers battery life is important to get the pictures that they want, and for them, direct measurements of battery life could be a lot more meaningful than staring only at jpegs. I think that the measured performance of raw files is an important indicator of critical elements of image quality if tests are properly conducted and interpreted (something that regretteably often does not happen).

I think it is important to know that raw-files usually represent a linear measurement of light hitting the sensor (limited by noise and saturation). No shoulder, no s-curves, ... It is equally essential to know why a non-linear response is often applied before the image is displayed on a monitor or print. Human visual perception plays a part in it, but only to answer the "whys", not the "hows".

-h
« Last Edit: December 27, 2011, 05:13:08 pm by hjulenissen »
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #71 on: December 27, 2011, 05:27:30 pm »

If you don't want to tell us what you are claiming, can you please stop claiming that digital raw files have s-curves, shoulders, or similar things? I am sorry, no.Sure:
http://www.luminous-landscape.com/forum/index.php?topic=57543.0

-h
Unless you do, please don't quote me back ever again. I don't talk anonymously or share photographic discussion with non-photographers. Theodoros. www.fotometria.gr
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hjulenissen

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Re: What about 36MP DSLRs?
« Reply #72 on: December 27, 2011, 05:42:33 pm »

Unless you do, please don't quote me back ever again. I don't talk anonymously or share photographic discussion with non-photographers. Theodoros. www.fotometria.gr
Every time I see a misleading or erroneous post in here, I will try to make a polite reply that aids the reader, just like I expect everyone else to do.

If you don't like being questioned or being quoted, my best advice would be spending your time elsewhere, using your camera for instance.

-h
« Last Edit: December 27, 2011, 05:50:43 pm by hjulenissen »
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #73 on: December 27, 2011, 05:52:44 pm »

Every time I see a misleading post in here, I will try to make a polite reply that helps the reader steer away.

If you don't like being questioned or being quoted, my best advice would be spending your time elsewhere, using your camera for instance.

-h

Unless you do, please don't quote me back ever again. I don't talk anonymously or share photographic discussion with non-photographers. Theodoros. www.fotometria.gr
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jeremypayne

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Re: What about 36MP DSLRs?
« Reply #74 on: December 27, 2011, 09:07:10 pm »

As before, Theodoros, when you make false claims and parade your opinions as facts ... you will be challenged.

Count on it.
« Last Edit: December 27, 2011, 09:27:19 pm by Jeremy Payne »
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AndreasE

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Re: What about 36MP DSLRs?
« Reply #75 on: December 27, 2011, 09:24:50 pm »

The only thing that I am saying is that the linear raws that result from the analog to digital conversion, have compressed highlights and shadows, ie they are a linearized S-slope, that tries to behave like film was, its obvious when you open the files on your raw converter, just observe a high contrast scene carefully. This is different to the latitude that the data may have which allows us to produce a new S-slope during PP (D/A conversion). Regards, Theodoros. www.fotometria.gr

Theodoros,
it seems to me that your repeated claims are your unqiue POV. You are using the some key concepts in sloppy terms.

  • The operation of the imager is linear. The number of electrons produced is directly proportional to number of photons recorded.
  • The A/D conversion of basically all CMOS and CCD cameras is linear. There used to be in the past logarithmically A/D converters around. Bascially all of them have been replaced by linear A/D converters with higher resolution (to provide enough precision in later software based mapping if needed). To my knowledge an A/D converter with a mixture of a log function at the edge and linear for the center range never existed. You can for sure point to some URLs of product sheets to prove the argument you are making.
  • Your argument about the raw converter lacks precision. The RAW file opened by the RAW converter contains linear per sensel data points from the imager and A/D conversion. Added with some metadata (like QE, spectral imformation of the bayer filter, etc ...), a RAW converter is able to convert during the demosaic process the linear information to a model with a S-slope. The S-slope is only created after the demosaic process and hence is not part of what most people treat as the information in the RAW file produced by the imager and A/D converter.
  • One of the few RAW converters able to allow a look at the RAW data BEFORE the demosaic process convertes them is "dcraw" with the options -D and -4

Looking forward to see your external sources, or personal analysis to understand your view. Please be so kind and don't repeat your claims again - we read them already and like to move to the next stage.

rgds,
Andy
« Last Edit: December 27, 2011, 09:30:23 pm by AndreasE »
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BernardLanguillier

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Re: What about 36MP DSLRs?
« Reply #76 on: December 27, 2011, 11:57:45 pm »

Unless you do, please don't quote me back ever again. I don't talk anonymously or share photographic discussion with non-photographers. Theodoros. www.fotometria.gr

Fotometria,

Without questioning your intellectual superiority, do you think it could make sense to assess the possibility that the rest of the World may be right? :-)

Cheers,
Bernard

fotometria gr

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Re: What about 36MP DSLRs?
« Reply #77 on: December 28, 2011, 04:15:19 am »

Theodoros,
it seems to me that your repeated claims are your unqiue POV. You are using the some key concepts in sloppy terms.

  • The operation of the imager is linear. The number of electrons produced is directly proportional to number of photons recorded.
  • The A/D conversion of basically all CMOS and CCD cameras is linear. There used to be in the past logarithmically A/D converters around. Bascially all of them have been replaced by linear A/D converters with higher resolution (to provide enough precision in later software based mapping if needed). To my knowledge an A/D converter with a mixture of a log function at the edge and linear for the center range never existed. You can for sure point to some URLs of product sheets to prove the argument you are making.
  • Your argument about the raw converter lacks precision. The RAW file opened by the RAW converter contains linear per sensel data points from the imager and A/D conversion. Added with some metadata (like QE, spectral imformation of the bayer filter, etc ...), a RAW converter is able to convert during the demosaic process the linear information to a model with a S-slope. The S-slope is only created after the demosaic process and hence is not part of what most people treat as the information in the RAW file produced by the imager and A/D converter.
  • One of the few RAW converters able to allow a look at the RAW data BEFORE the demosaic process convertes them is "dcraw" with the options -D and -4

Looking forward to see your external sources, or personal analysis to understand your view. Please be so kind and don't repeat your claims again - we read them already and like to move to the next stage.

rgds,
Andy

Andy do you question that some pixels of a sensor can be directed to reject a number of photons in a way that saturatated input to the A/D converter can be prevented or delayed? Do you question that some other pixels can be directed to amplify (with noise of course) the light that they receive?
 If you don't question that the above can be easily done, wouldn't the application of both the above result in raws being a linearized result of an S-slope? Please be careful, I am not asking you about your opinion if it happens (we'll come to this later) nor the above has anything to do with linear or not A/D convertors. Its a simple question if it can be done easily. Regards, Theodoros. www.fotometria.gr
« Last Edit: December 28, 2011, 05:30:29 am by fotometria gr »
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fotometria gr

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Re: What about 36MP DSLRs?
« Reply #78 on: December 28, 2011, 04:36:10 am »

Fotometria,

Without questioning your intellectual superiority, do you think it could make sense to assess the possibility that the rest of the World may be right? :-)

Cheers,
Bernard

Bernard, please look above to number 77, it's a question (or two) for you as well. I don't believe that the "rest of the world" would disagree in whether saturation and noise can be "tweeked" before the information enters the A/D converter nor they would disagree that this wouldn't affect the linearity of the Raw files, since the a/d converter would assume that the input that its allowed to "see" is the whole input. Regards, Theodoros. www.fotometria.gr
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ErikKaffehr

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Re: What about 36MP DSLRs?
« Reply #79 on: December 28, 2011, 07:55:28 am »

Hi,

The sensor is essentially a device that collects photons, converts them to free electrons and stores the electrons in small capacitor. At readout the voltage over the capacitors is measured (on CMOS) or the electrons themselves be shifted out and electron charge measured (in CCD). The sensors are linear devices, little can be done about that. The signal can be amplified before Analog Digital Conversion (ADC).

It would be feasible to have nonlinear amplification, but it would make little sense as the ADC-s used span a greater range than SNR (Signal Noise Ratio).

All measured data I have seen on RAW files was linear.

Best regards
Erik

Andy do you question that some pixels of a sensor can be directed to reject a number of photons in a way that saturatated input to the A/D converter can be prevented or delayed? Do you question that some other pixels can be directed to amplify (with noise of course) the light that they receive?
 If you don't question that the above can be easily done, wouldn't the application of both the above result in raws being a linearized result of an S-slope? Please be careful, I am not asking you about your opinion if it happens (we'll come to this later) nor the above has anything to do with linear or not A/D convertors. Its a simple question if it can be done easily. Regards, Theodoros. www.fotometria.gr
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