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Author Topic: How "raw" are raw files?  (Read 3364 times)

V8Beast

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How "raw" are raw files?
« on: March 21, 2012, 02:30:10 PM »
With all the comparisons of high ISO raw files that's been going on lately, my pea brain needs some clarification on a few issues. My understanding has always been that raw files represent the information that the camera actually captures in its purest form, with no manipulation whatsoever. However, others have mentioned that Nikon bodies "cook" their files by applying in-camera noise reduction. Obviously, at that point a raw file doesn't represent what the camera captured in it's purest form, and therefore does not accurately represent the performance of the sensor. Does Canon do the same thing with its raw files?

This raises a few more issues. If a camera applies noise reduction to its raw files, what's to say that it can't extend dynamic range with in-camera processing as well? I defer whether or not extending DR of raw files via in-camera software is even possible to the real tech heads on here, but if a camera did do this, how would you even know unless a manufacturer disclosed this info in its literature? 

On one hand, I can see why you'd want a true, unprocessed raw file as a means of measuring sensor performance. On the other hand, if in-camera processing is sophisticated enough to improved overall IQ to the point where that a photographer can't even tell that in-camera processing was applied in the first place, who really cares?

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How "raw" are raw files?
« on: March 21, 2012, 02:30:10 PM »

Spooky

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Re: How "raw" are raw files?
« Reply #1 on: March 21, 2012, 02:47:39 PM »
I'm fairly sure that all manufacturers apply some processing to their raw files, and it varies between models, hence new raw converters for Lightroom and PS to read and load the raw files from new cameras. The raw file is the purest from the point that it is not the compressed, colour spaced, sharpness, contrast, white balance tweaked jpeg file, but it almost certainly has been processed in camera. I wouldn't worry about this as this is what we get and is the best that Canon engineers have deemed we will have and we can't change that unless there is a firmware update.

te4o

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Re: How "raw" are raw files?
« Reply #2 on: March 21, 2012, 03:03:35 PM »
Bering this in mind could we have a list of the most used RAW converters in particular with their strengths and weaknesses?
We had a lot of discussions about generalized ' Raw vs the rest of the world' without much emphasis on the RAW (on everything else though). I'd like to know do you use several RAW converters in your workflow for different shots and for different purposes or just stick to one converter-organizer like LR or Aperture or whatever?
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V8Beast

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Re: How "raw" are raw files?
« Reply #3 on: March 21, 2012, 03:18:03 PM »
I wouldn't worry about this as this is what we get and is the best that Canon engineers have deemed we will have and we can't change that unless there is a firmware update.

I'm not worried about it at all. I trust the egghead engineers at Canon have done their homework and created algorithms that produce the best raw files as possible. If each manufacturer applies some processing to all its raw files, then I find it somewhat silly to so heavily scrutinize raw files as if they're a genuine representation of sensor technology. 

3kramd5

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Re: How "raw" are raw files?
« Reply #4 on: March 21, 2012, 03:26:24 PM »
There has to be a certain amount of processing. The sensor develops charge, while the raw contains brightness data. The a-d circuitry converts (processes) accumulated charge in each photosite to a relative brightness, and very likely other operations occur at that time (ie BEFORE the data is rastered).

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Radiating

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Re: How "raw" are raw files?
« Reply #5 on: March 21, 2012, 04:14:34 PM »
With all the comparisons of high ISO raw files that's been going on lately, my pea brain needs some clarification on a few issues. My understanding has always been that raw files represent the information that the camera actually captures in its purest form, with no manipulation whatsoever. However, others have mentioned that Nikon bodies "cook" their files by applying in-camera noise reduction. Obviously, at that point a raw file doesn't represent what the camera captured in it's purest form, and therefore does not accurately represent the performance of the sensor. Does Canon do the same thing with its raw files?

This raises a few more issues. If a camera applies noise reduction to its raw files, what's to say that it can't extend dynamic range with in-camera processing as well? I defer whether or not extending DR of raw files via in-camera software is even possible to the real tech heads on here, but if a camera did do this, how would you even know unless a manufacturer disclosed this info in its literature? 

On one hand, I can see why you'd want a true, unprocessed raw file as a means of measuring sensor performance. On the other hand, if in-camera processing is sophisticated enough to improved overall IQ to the point where that a photographer can't even tell that in-camera processing was applied in the first place, who really cares?

Both Canon and Nikon ALREADY use processing to increase the dynamic range of RAW files. Nikon's processing is several times more advanced than Canon's though.

Nikon cooks the raw files for noise reduction ONLY during long exposures.

Beyond that there is nothing done to the raw files as far as I've been able to find, and real world tests seem to confirm that no noise reduction is applied to the raw files.

V8Beast

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Re: How "raw" are raw files?
« Reply #6 on: March 21, 2012, 04:32:25 PM »
Both Canon and Nikon ALREADY use processing to increase the dynamic range of RAW files. Nikon's processing is several times more advanced than Canon's though.

Very interesting. So is the Sony/Nikon Exmor sensor that much better than Canon's full-frame sensors, or is some of its advantage in DR attributable to better in-camera processing? Is contrast and color reproduction/saturation also tweaked by in camera before the information is recorded as a raw file?

IMHO, all that really matters is the end product, regardless how large of a role in-camera processing and the sensor itself plays in the equation. I suppose the notion that raw images accurately reflect sensor performance is bogus, but not quite as bogus as a jpeg.

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Re: How "raw" are raw files?
« Reply #6 on: March 21, 2012, 04:32:25 PM »

grahamsz

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Re: How "raw" are raw files?
« Reply #7 on: March 21, 2012, 04:59:57 PM »
This is a pretty interesting discussion. Given some of the discussions here from simple benchmarking tests, you'd believe that Nikon are absolutely destroying Canon at low ISOs. While I'm certainly impressed with what Nikon can do at 36MP, there are comparison areas where I think the equivalent Canon image is stronger.

I'm sure it'd be possible to design a sensor and preprocessing logic to create really strong results on synthetic benchmarks. It's the engineering equivalent of teaching to the test, and we've seen in in the past with processor and gpu benchmarks on PCs.

I wonder how well a benchmark can control for something like that.

Meh

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Re: How "raw" are raw files?
« Reply #8 on: March 21, 2012, 05:05:03 PM »
There has to be a certain amount of processing. The sensor develops charge, while the raw contains brightness data. The a-d circuitry converts (processes) accumulated charge in each photosite to a relative brightness, and very likely other operations occur at that time (ie BEFORE the data is rastered).

Not really.  To refer to the ADR as "processing" isn't quite right and I'm not sure what you mean by "relative" brightness.  What are you suggesting it's relative to?   The ADC is a straight-forward digitization of the accumulated charge and it's generally believed to be a linear conversion which if correct would suggest there no "processing" per se.

It's well known that Nikon clips the lowest signals just above the noise floor which gives the appearance of a less noisy RAW file but I've never heard they apply any significant/advanced NR to the RAW data.

Meh

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Re: How "raw" are raw files?
« Reply #9 on: March 21, 2012, 05:08:06 PM »
Both Canon and Nikon ALREADY use processing to increase the dynamic range of RAW files. Nikon's processing is several times more advanced than Canon's though.

You appear to state this as a matter of fact.  Can you explain further what processing each is doing increase DR of the RAW file, why you believe Nikon is several times more advanced than Canon, and where you're getting your information from?

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Re: How "raw" are raw files?
« Reply #10 on: March 21, 2012, 05:26:26 PM »
Nikon cooks the raw files for noise reduction ONLY during long exposures.

They cook the RAW at speeds slower than 1/4.

I don't consider that a particularly long exposure.  Some landscape guys would consider that a moderately fast exposure, and astrophotography guys consider that practically "bullet time".

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3kramd5

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Re: How "raw" are raw files?
« Reply #11 on: March 21, 2012, 05:37:00 PM »
and I'm not sure what you mean by "relative" brightness.  What are you suggesting it's relative to?   

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Re: How "raw" are raw files?
« Reply #12 on: March 21, 2012, 05:39:55 PM »
Nikon cooks the raw files for noise reduction ONLY during long exposures.

When I decided if to get the D7000 or the 60D back then, I read a lot about Canon vs. Nikon. While I don't have the exact link (I think it was somewhere on dpreview), a Nikon guy examined the D7000 raw files and compared them to the D90. The result: Esp. on the D7000 the raw files are heavily modified if iso speed increases, and this results in the raw data files to have significantly different sizes on different iso settings. Afaik, it's easier to get "raw" raw data out of the aps-c Canons than out of the D7000.

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Re: How "raw" are raw files?
« Reply #12 on: March 21, 2012, 05:39:55 PM »

Meh

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Re: How "raw" are raw files?
« Reply #13 on: March 21, 2012, 06:25:52 PM »
and I'm not sure what you mean by "relative" brightness.  What are you suggesting it's relative to?   

Charge

Ok but I wouldn't put it that way exactly.   When you say "relative brightness" that would typically mean how bright something is compared to something else... either a ratio or difference in magnitude.

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Re: How "raw" are raw files?
« Reply #14 on: March 21, 2012, 06:31:08 PM »
Nikon cooks the raw files for noise reduction ONLY during long exposures.

When I decided if to get the D7000 or the 60D back then, I read a lot about Canon vs. Nikon. While I don't have the exact link (I think it was somewhere on dpreview), a Nikon guy examined the D7000 raw files and compared them to the D90. The result: Esp. on the D7000 the raw files are heavily modified if iso speed increases, and this results in the raw data files to have significantly different sizes on different iso settings. Afaik, it's easier to get "raw" raw data out of the aps-c Canons than out of the D7000.

I believe the reason for the different file sizes is that higher ISO files are noisier and therefore the RAW files can not be compressed as much as the less noisier files from lower ISO settings.  And yes, RAW files are also compressed but only using lossless compression algorithms (rather than jpeg which is a lossy compression scheme).

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Re: How "raw" are raw files?
« Reply #14 on: March 21, 2012, 06:31:08 PM »