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05-29-2010, 03:40 PM   #1
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Are high ISO considerations based on jpeg or raw?

when reviews come out for something like the K-7 or K-x and they say it's great or not so great at a given ISO, do they mean based on the JPEG or the RAW or does it matter?

05-29-2010, 05:19 PM   #2
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Good review sites usually mention both JPG and RAW high ISO performance. Only some specialised ones (eg dxomark.com) stick to covering RAW performance.

It matters only to the degree you want it to matter.

RAW images give you options in post-processing which mean you can use your own computer and software to get higher image resolution, greater colour depth, more sharpness, better highlight recovery, dynamic range etc out of your images at any ISO, potentially.

JPG gives you convenience, and images according to how the in-camera processing has been setup by you or the camera defaults to deliver them to you.

So the JPG high-ISO results will reflect in-camera settings, the RAW ISO results will reflect your decisions about how to process the data-dump from the camera sensor (a raw data-dump is all essentially a RAW image file is).

Often times the out-of-camera JPG's won't work as well for high ISO as the RAW file output because the camera has decided to apply stuff like heavy noise reduction to the image, which can degrade image quality. High ISO RAW files won't usually have any of that stuff applied, so can come out looking a lot better after out-of-camera post processing.
05-29-2010, 05:55 PM   #3
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Most regular Testreports are based on jpeg ooc,in Germany are all Tests made in jpeg,standard configuration....
still any questions??

Best regards,Andy
05-30-2010, 03:20 PM   #4
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When testreports are based on jpeg, I have noticed that the choice is often explained by jpeg being camera-dependent only, whereas raw also depends on raw converter software, which again comes in dozens of brands, versions, and with a well of possible pp-options. Raw makes it less trivial to compare different cameras, because it can be difficult to know if you are testing cameras or raw-converters.

Not all raw-converters are available for all cameras, and even if you restricted the test to LightRoom 2.6.1 build 632, with a static set of parameters, it wouldn't necessarily be fair to all the different raw-formats out there.
By sticking to jpeg, the tester omits some non-trivial choices. And it's faster, easier, and less work

05-30-2010, 05:22 PM   #5
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QuoteOriginally posted by fredrikj Quote
When testreports are based on jpeg, I have noticed that the choice is often explained by jpeg being camera-dependent only, whereas raw also depends on raw converter software,<snip>
By sticking to jpeg, the tester omits some non-trivial choices. And it's faster, easier, and less work
And horribly inaccurate. The less the noise at high ISO, the less the detail as well. The reviews of the K10 when it first came out suffered badly from this inaccurate assessment.
05-31-2010, 07:51 AM   #6
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QuoteOriginally posted by Canada_Rockies Quote
And horribly inaccurate. The less the noise at high ISO, the less the detail as well. The reviews of the K10 when it first came out suffered badly from this inaccurate assessment.
Yes, I agree. And I never shoot jpeg myself, so I'm dissapointed by the amount of jpeg-based comparisons in tests, even in serious magazines.
Just wanted to pass on what the reason for this could be.
06-03-2010, 02:40 AM   #7
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Actually it seems like if you switch on any noise correction in k-x, it affects RAW files as well as jpegs so it' does not make difference I wish it'd only affected jpegs but my tests show the opposite.
06-03-2010, 09:29 AM   #8
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QuoteOriginally posted by fredrikj Quote
And I never shoot jpeg myself, so I'm dissapointed by the amount of jpeg-based comparisons in tests, even in serious magazines.
Me, too especially when reviewers say "jpgs are soft straight out of the camera" as if they don't know there are settings to make changes.

06-03-2010, 01:40 PM   #9
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@oleni: This is not the case. Any noise reduction other than Dark Frame Subtraction only affects the jpeg. What you see on the camera's viewscreen is an embedded jpeg which is why it is affected by the noise reduction.

Jack
06-03-2010, 02:53 PM   #10
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The deal is that the high ISO NR you can turn on or off only affects JPEG, but there is also NR that *cannot* be turned on or off (it simply cuts in on its own at some particular ISO level tha varies from camera to camera) that affects both JPEH and RAW. This has been conclusively proven by several people who have written their own software to analyze the data like DXO, Oleg_V, and GordonBGood; it's far beyond what most of us could attempt to refute.
06-03-2010, 08:41 PM   #11
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QuoteOriginally posted by Marc Sabatella Quote
The deal is that the high ISO NR you can turn on or off only affects JPEG, but there is also NR that *cannot* be turned on or off (it simply cuts in on its own at some particular ISO level tha varies from camera to camera) that affects both JPEH and RAW. This has been conclusively proven by several people who have written their own software to analyze the data like DXO, Oleg_V, and GordonBGood; it's far beyond what most of us could attempt to refute.
when you open PEF in DCU it contains some NR which you can turn off (spurious signal), which adds significant color noise. Also if "high ISO NR" was turned on then preset also includes random noise NR which is what that option essentially does. it can also be turned off.

When I open the same pef in irfanview, for some reason it contains the same default NR but you can't turn it off.

this makes no sense unless they keep full resolution jpeg in the pef which is unlikely.

so maybe irfanview uses the same code that DCU use, which performs pre-processing ?

anyway if those testers used the same method to open pef then probably they got such results for this reason...
06-03-2010, 08:56 PM   #12
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I think what Mark is saying is that some experts have been able to deduce that Pentax (like Nikon, Canon and others) do introduce some noise reduction into the image processing engines of their DSLR's, which means the saved 'RAW' images do actually already embody some NR.

So the RAW isn't really 'RAW' or a 'pure' capture of the data from the sensor, simply because in the chip-level firmware of the camera, somewhere along the line between image capture and RAW file saving there has been some in-camera processing of the data to apply some form or level of NR.

What you are encountering in IrfanView and DCU is the additional peculiarities or 'personality' every single software-based RAW converter brings to the RAW conversion process. This operates on top of any processing done at the hardware level of the camera.

However you cut it, no DSLR gives it's users 'pure' RAW data in their RAWs. Somewhere along the line, starting at low level in the hardware, the data captured by the sensor gets processed by software in order to make it intelligible and improve it. Often times this may involve some NR but also other processing too.
06-03-2010, 10:06 PM   #13
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I understand this but we don't know how did those "experts" obtain raw data they tested. even DCU does not show the REAL "raw" unless you do some setup after opening the pef image, what about other programs? If they used DNG then it's not even a "real" pentax RAW.
06-04-2010, 03:39 AM   #14
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QuoteOriginally posted by olenl Quote
even DCU does not show the REAL "raw" unless you do some setup after opening the pef image,
Sorry, if you want to see the real raw data in the pef file then open it in notepad A raw file must be processed to show you an image - the processing done to get the image differs in every software.
06-04-2010, 04:24 AM   #15
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QuoteOriginally posted by olenl Quote

When I open the same pef in irfanview, for some reason it contains the same default NR but you can't turn it off.

this makes no sense unless they keep full resolution jpeg in the pef which is unlikely.
I believe that the standard setting for irfanview is to use the embedded jpeg, and that most rawfiles does include a full resolution jpeg.
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