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Author Topic: Why DNG  (Read 12010 times)
Paul Gulliver
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« Reply #15 on: September 21, 2009, 11:01:16 AM »

Ok thanks for the replies, I think at the moment I will convert my raw files to dng at the import stage, keep the raw files untouched and process the dng files.
It seems to be as broard as it is long at the moment as to what may happen in a few years time but at least I will have 2 options available  Wink
I'm not a pro and don't take large quantities of photos so storage space is not a problem.

Paul
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snoopy
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« Reply #16 on: July 11, 2010, 03:32:45 PM »

Hi

in the whole DNG vs. propriatory RAW format discussion, I am missing a critical point. Maybe I am overseeing something or I am too stupid to understand this. So hopefuly someone can explain this to me:

Adobe improves almost every year its RAW converter. Both, for converting the manufacturers RAW images and the DNG converter.

If I would have converted i.e. a NEF file in 2006 to DNG, then this conversation wold have been done with the know-how and the status quo of RAW conversion of 2006.

Once converted into DNG, it is DNG with this status quo. So if I open it in 2010, I have a DNG file with the conversion qulaity of 2006.

On the other hand, if I would have kept my RAW-NEF file of 2006 and would convert it only now in 2010 to DNG, I would get a better DNG image quality. But I can not improve the image quality of the 2006 DNG file in 2010, since the conversion was already done in 2006.

So as far as I understand this, it is great to have an open format with DNG, but at the same time I "lock-in" the conversation quality of the year of conversion, similar to Jepg conversions.

Is this correct or do I miss here something? Did somebody tried to compare this with real files?

Thanks in advance

Dirk
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BobSmith
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« Reply #17 on: July 11, 2010, 08:08:18 PM »

The raw data in your 2006 DNG hasn't changed from what was in the original NEF.  Today's DNG has more capabilities for storing (and validating) raw data and various metadata to go along side, but it's not altering the original raw data.  You can take your 2006 DNG and convert it to DNG again with todays convertor and get the same thing as converting the original NEF with today's DNG convertor.

Bob Smith
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snoopy
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« Reply #18 on: July 11, 2010, 11:16:12 PM »

The raw data in your 2006 DNG hasn't changed from what was in the original NEF.  ..... but it's not altering the original raw data.  You can take your 2006 DNG and convert it to DNG again with todays convertor and get the same thing as converting the original NEF with today's DNG convertor.

Bob Smith

Hi

and this is, what I do not understand and which is hard for me to believe. As far as I understood (in this example), the 2006 NEF-DNG conversion was done with specific algorythms. Once applied, every bit of the NEF file has a corresponding other bit in the DNG file in that way as Adobe thought in 2006 this would be the most appropriate way of interpreting it.

Now it is set in the 2006 DNG file, bounded in this 2006 interpretation of the NEF bit. How then can it be possible, to interpret those bits of the 2006 DNG file in 2010 in the SAME different way, if I threw the NEF file in 2006 away as if I would have kept the original NEF and would use this instead of a 2006 DNG?

IMHO, i can only optimize the 2006 DNG file in the frame of the 2006 DNG interpretation. But I can not reinterprete the original NEF, since this is gone. So the improvement through better knowledge of Adobe is most likely bigger when converting in 2010 from the 2006 NEF file instead of the 2006 DNG file.

I think of this DNG conversion in the same way as a conversion from NEF Raw to Jpeg. Once done, it is set with all its limitations of 2006. 4 years later, I get better conversion results of the same NEF Raw file into Jpeg then the old 2006 conversion. But I will not achieve the same improvemnets if I take the jpeg 4 years later and run the newest algorythms on it.

Of couse DNG in better then jpeg. But I used this example to explain my "understanding-problem" for the boundaries of a conversion process 2006 vs. 2010 better...

Can anybody help me out here what I do wrong with my logic?

Thanks

Dirk
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ScottBuckel
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« Reply #19 on: July 12, 2010, 11:30:05 AM »

Dirk -

I think you are making an assumption that is not correct, if you have a DNG converted in 2006 you can use the new adobe algorithms to process the file and completely utilize the current conversion algorithms and save them back to the file.  The short coming is if the algorithms change the older images may look a bit different than they did in 2006 when you use a newer browser or raw converter. 

Now that said the raw image data in the raw file is never changed, the only change is the set of instructions to apply to the raw image data.  This is the keystone of nondestructive editing.

Scott
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Scott Buckel
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BobSmith
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« Reply #20 on: July 12, 2010, 02:37:55 PM »

The whole use of the word "conversion" is where the misunderstanding is.  The DNG convertor doesn't "convert" the data.  It simply converts the way it is stored.  Using DNG Convertor to convert your Nikon raw into a DNG is nothing like using any convertor to render an image.  In that case, yes you've locked in a rendering possible only with the technology available at the time the rendering was made.  A DNG conversion is not a rendering.  It's simply a re-defining of the way the raw data is stored.  It puts data from a variety of different proprietary formats into a more standardized scheme... so that it can be read and manipulated in similar ways regardless of the originating camera.  Run an older DNG through a newer DNG convertor and you gain the added features of the newer storage package without altering your original raw image data at all.

Bob Smith
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raka
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« Reply #21 on: July 12, 2010, 02:56:11 PM »

...  It puts data from a variety of different proprietary formats into a more standardized scheme... so that it can be read and manipulated in similar ways regardless of the originating camera.  ...

Bob Smith

this was what i thought as well, that DNG would shield me from the madness of hundreds of incompatible camera specifc RAW formats.

but as you can see from my other post here, it is not the case. even when saving a DNG at maximum backwards ACR (2.4) and DNG (1.1) compatibility, it may remain unreadable to apps and systems that have no problem with other DNG files.

the irony is that OS X can actually read the camera RAW files (Panasonic LX3 RW2 files), but NOT once they are converted to DNG, regardless of compatibility mode.

http://thedambook.com/smf/index.php?topic=4750.0

- pieter
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peterkrogh
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« Reply #22 on: July 25, 2010, 08:25:20 PM »

Pieter,
I explained in the other thread what is happening there. The Apple OS has not been updated to deal with the compatibility settings, I expect. It should be able to parse the file, but this is a different type of implementation than Apple has traditionally been doing with DNG files.

As to the original question, Bob and Scott are right - DNGs that are made after version 1.1 (that would have been before the publication of my first book) will have all the "rawness" to the data.  So you get the benefit of upgraded software capabilities.

Peter
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JoeThePhotographer
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« Reply #23 on: February 11, 2011, 10:22:32 AM »

1. The DNG can contain a rendering showing the image as I want it to be seen, regardless of what program I look at it with (well, as long as the program can see the embedded preview).

What programs out there use the embedded preview? 

Lightroom?  [If so, does that mean that there is no need for the LR catalogue to generate previews?]

Bridge? 

Adobe Premiere Pro? 

Any third party? 

Is there any codec at all for Windows 7 64 bit?

Joe
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Roelof
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« Reply #24 on: February 11, 2011, 12:55:47 PM »

Quote
Is there any codec at all for Windows 7 64 bit?
Yes, i use FastPictureViewerCodecPack 2.4. It's about 5 dollar...
http://www.fastpictureviewer.com/codecs/
Roelof
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NYBG
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« Reply #25 on: August 11, 2011, 10:20:56 AM »

I have a compelling reason to convert my TIFFs to DNGs: space (http://digitalphotorepro.blogspot.com/2011/08/global-plants-initiative-jstor.html).

I am facing a storage shortage right now. I have 15 terabytes of TIFFs sitting in an archive that are rarely, if ever, used. On top of that, they are duplicated offsite. So, by converting to DNG, I estimate that I can recover about 7.5 terabytes!

This is essential, because with additional imaging projects coming online, I figure I am going to need at least 5 terabytes of space through the end of 2011.

I have been reading to see if there are any downsides to converting TIFFs to DNG. So far, it seems that the only downside is the perception that TIFF is somehow more 'archival' a format. But, as a colleague of mine from NYU's library said, there is no archival format - preservation is an institutional commitment that requires ongoing human diligence (http://digitalphotorepro.blogspot.com/2011/04/digitization-special-interests-group.html).

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NYBG
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« Reply #26 on: December 02, 2011, 10:24:34 AM »

Holy cow - I just read my last post from back in August... August!

I just finished (it's December!) converting about 125,000 TIFFs to DNG. The Tiffs started around 210 MB, the DNGs are about 90 MB. I starte with 15.8 TB of TIFFs and ended up with 6.8 TB of DNGs - reclaiming 9 TB of space on New York Botanical Garden's servers.

I installed Lightroom on seven networked computers and converted batches of 1200 images at a time on each machine. (While I would have preferred to have used the DNG converter, for some reason it did not work well over the network.)

 
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