DNG vs. original RAW in the long term

G

gargamel

Feb 16, 2014
47
0
#1
Hi everyone,

I have a question regarding options for long-term archiving of RAW files.

What are the advantages and disadvantages?

I am asking, because Canon might change its RAW format and optimise it for upcoming new cameras, and sooner or later RAW converters may drop support for old RAW files (considered outdated). I don't think, this will happen any time soon, though. DNG seems to be comparable to PDF/A, which is now the preferred format for electronic archiving of documents.

In another thread it was recommended to always keep the original RAW files, because RAW converters improve over time, and converting old RAW files with new converters would potentially give significantly better results than what was possible a few years ago. The question is, how long will old RAW files be supported in new converters.

But the same questions is valid for DNG, too. If I would convert all my RAW files to DNG, now, will this be a truly lossless conversion? Or could it be, that DNG conversion improves over time, too? And: How much does conversion from Canon RAW to DNG depend on the converter? Will Adobe products give different results, than, say, the DNG converter that comes with open source packages, such as Digikam/Showfoto?

I have no experience with all of this, but I am planning to archive my images, soon, and I just reading about backup and archiving strategies, formats and so on. Therefore I am very interested in your advice. Thanks in advance!

gargamel


P.S.: Of course, I have written http://www.canonrumors.com/forum/index.php?topic=3113.0, before posting.
 
#3
AcutancePhotography said:
gargamel said:
Canon might change its RAW format and optimise it for upcoming new cameras, and sooner or later RAW converters may drop support for old RAW files (considered outdated).
Click to expand...

Has any camera company done this in the past?

Are there RAW formats that have no readers today?
Click to expand...

Not that I know of, as I said. But then, to my knowledge, RAW files are similar to TIFF files, and programs that support TIFF may not support YOUR Tiff... DNG support is found in many software products, nowadays, and it seems to be an open standard, similar to PDF/A, but different from proprietary standards, such as GIF or BMP (Microsoft). However, I take your point, that there is no practical advantage related to this, at the moment.

gargamel
 
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#4
Software doesn't "disappear", it may no longer be updated, but you'll always be able to find it on the web.

How about this, if you're REALLY worried about it, archive your RAW files WITH a piece of software that does the conversion.

Personally, I'm not worried about it, there are SO MANY images out there using Canon's RAW format I don't see any software "dropping" it any time soon.

As for DNG, while the image data might be losslessly captured, there are other elements of the RAW file that may not, meta data being one thing. I'm not sure what else is in a RAW file that DNG doesn't store, but I'm sure there's something.
 
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#6
I think the bigger issue would be operating systems supporting the older software . Windows 7 64bit made a lot of useful software obsolete ( this was actually because the installer would not run, not the program it's self). Raw files are just data files so as long as there is a need someone will probably make a reader or converter for them.
 
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#7
Thanks for all your good and useful replies, so far. Following the discussion, up to now it seems, that there is no real point in using DNG over RAW for long-term archiving purposes, while DNG may still be useful for transferring the image data to some software that doesn't support Canon's RAW format. Further opinions welcome, but at the moment I would conclude that archiving RAW on two separate disks would be the safest option.

gargamel
 
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#8
gargamel said:
In another thread it was recommended to always keep the original RAW files, because RAW converters improve over time, and converting old RAW files with new converters would potentially give significantly better results than what was possible a few years ago
Click to expand...
This is definitely true, I've notice an improvement in ACR over time, and so I go back and re-convert my favorite photos every year or so to see if they turn out better. Highlight recovery and denoising have gotten a LOT better in the last 3-4 years.

hgraf said:
Personally, I'm not worried about it, there are SO MANY images out there using Canon's RAW format I don't see any software "dropping" it any time soon.
Click to expand...
And even if the major programs did drop it, two things would happen

1: It would be very publicly announced, probably with about 5000 posts on this forum and every other forum. And someone will make the tool that turns all your RAW format photos into whatever the new format is en masse.

2: Someone would create a legacy converter that works on every platform. I mean, Magic Lantern alone creates converters for the proprietary formats that create for RAW video and HDR video and Dual ISO shots...they'd easily be able to create a CR2 converter for everyone if they made that format obsolete.

So, my conclusion is to archive them in their native format. Because then you know they are lossless. And in the future, should that change, converting them will not be any more difficult than doing it now.
 
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#10
How do you plan to archive the photos, whichever format you select? Just curious.

Interesting: the automatic ad (or whatever it is) that pops up on this thread between the posts, at least for me, is for a file converter. Is everyone else getting that? I presume that whatever software Canon Rumors uses to place those ads reads the content of the thread and selects an ad that is pertinent (I also get a lot of "Canon vs. Nikon" ads).
 
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#11
dppaskewitz said:
How do you plan to archive the photos, whichever format you select? Just curious.
Click to expand...

That's a good question.I have seen more media broken by firmware, drm , drivers, etc that made It only readable on the device it was original made on, especially cd's and DVD's. That's why when I build a system I make sure the dvd recorder is compatible with the most file types but that is no guarantee of future compatibility.
 
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#12
gargamel said:
Hi everyone,

I have a question regarding options for long-term archiving of RAW files.

What are the advantages and disadvantages?

I am asking, because Canon might change its RAW format and optimise it for upcoming new cameras, and sooner or later RAW converters may drop support for old RAW files (considered outdated). I don't think, this will happen any time soon, though. DNG seems to be comparable to PDF/A, which is now the preferred format for electronic archiving of documents.

In another thread it was recommended to always keep the original RAW files, because RAW converters improve over time, and converting old RAW files with new converters would potentially give significantly better results than what was possible a few years ago. The question is, how long will old RAW files be supported in new converters.

But the same questions is valid for DNG, too. If I would convert all my RAW files to DNG, now, will this be a truly lossless conversion? Or could it be, that DNG conversion improves over time, too? And: How much does conversion from Canon RAW to DNG depend on the converter? Will Adobe products give different results, than, say, the DNG converter that comes with open source packages, such as Digikam/Showfoto?

I have no experience with all of this, but I am planning to archive my images, soon, and I just reading about backup and archiving strategies, formats and so on. Therefore I am very interested in your advice. Thanks in advance!

gargamel


P.S.: Of course, I have written http://www.canonrumors.com/forum/index.php?topic=3113.0, before posting.
Click to expand...
Save your files and save a current copy of DPP that supports them.... that way, even if support is dropped in a future release, you still have a version that will work.
 
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#15
RLPhoto +1

I have been re processing some 3 year old 5DmarkII landscapes with DXO v10 and the improvements are quite marked. if they have been dinged then this wouldn't be possible. I also agree with the metadata being lost comments, made earlier, which may be where DXO are able to get the better results. I find it unexpected that while i really question the DXO Mark ratings of camera's, they do such a great job with Canon .CR2's

As someone who has experienced the improvements in raw convertors I totally agree with the advice.
 
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#16
My workflow keeps my RAW files for up to 6 months then I convert to DNG for Archiving purposes. I do so using Lossy compression. Doing this gives me a savings of anywhere between 50% and 80% depending on the photo. For example... for a full day wedding I typically shoot between 50GB - 75GB worth of Raw files... by time time I am done editing this could turn into over 100GB for a wedding. Converting to DNG can get my full wedding in around 25GB...

The biggest drawback here is that once you convert... you cannot convert back. And if you wish to use DPP in your workflow... your out as DPP only supports CR2 (from my understanding). If you are using ACR... I don't see to much difference as you can do everything with a DNG that you can do with a CR2. And as long as you are not creating new DNG'S from DNG's over and over... I really don't see a loss of quality issue.
 
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#17
gargamel said:
What are the advantages and disadvantages?
Click to expand...

I've converted everything to dng lately as I don't intend to switch away from LR/ACR, it's just too good - and multiple other apps start supporting dng.

Advantages of dng:
* metadata information inside the file, no xmp sidecar
* faster rendering vs. cr2 (if you "embed fast load data")
* you can update the jpeg preview to the post-processing state
* saves 20% disk space right away (if you drop the full res thumbnail that's in the cr2)
* lossy & downsized options while retaining dr and lossless wb adjustment

Disadvantages:
* some post-processing software doesn't support it, namely dpp & dxo
* xmp sidecar of cr2 gets written faster than the whole dng when updating metadata

However, the option to convert cr2 to raw won't go away, if you're not sure you can do it anytime in the future, even with the free Adobe DNG converter.

RLPhoto said:
They are always adding stuff to the DNG converters so converting them now could restrict what future developments would be possible later one. IE: Lens correction tech.
Click to expand...

I don't understand that - you can just update an older dng version to the new one.

Unless you're using lossy dng, the "converter" just *wraps* the raw data from the cr2 into a new dng container and adds a new thumbnail and fast load data (if you request it). Absolutely no file information is lost on cr2->dng, you could even write an app to convert it back.
 
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#18
what happens 20 years from now? the software that processes these files will not run on anything available then.
I am about to start scanning boxes of my negatives from the 80's and 90's. If I wait much longer, the scanners will become obsolete and chances of converting them later (much, much later, like 2035) are very slim. Unless the CR2 is still used many of our files will end up in "digital" boxes rather than shoe boxes.

The conundrum gets even worse if you think 100 years from now. Will there be any devices that can read our USB drives that far into the future? We have family images created 150 years ago and while not necessarily in greatest of conditions, we can at least view them. How do we archive for our grand kid's grand kids?

Anybody thinking that storing it on a hard drive or on the web is the answer probably did not get a chance to think about it more. Drives lose the information as they sit around, the interface might not be available, the Internet hosting company might not be in business any more and so on. . .

Any continuity of the data will be relying strictly on the data's owner to keep it current. Converting to the latest format even at a cost of losing some IQ is better than waking up 20 years from now and realizing your digital shoebox is unusable.

pierre
 
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#19
bluemoon said:
The conundrum gets even worse if you think 100 years from now.
Click to expand...

Fortunately, that won't pose a problem, at least not to me personally :p

As for data formats: The ISO makes a lot of fuss standardizing formats like pdf so the aliens can read our history in some millenia when the earth is taken over by the apes. And this pdf-a standard contains jpeg, and in every cr2 or dng (if you chose so) a jpeg is embedded.

As for converting debayering raw files: Adobe won't remove support for older cameras, and even if you can just use an older dng converter version - long after Canon is driven into bankruptcy by the Nikon trolls on CR :->
 
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#20
hgraf said:
Software doesn't "disappear", it may no longer be updated, but you'll always be able to find it on the web.

How about this, if you're REALLY worried about it, archive your RAW files WITH a piece of software that does the conversion.
Click to expand...

Yes, but that alone won't help. As has been said before, you need an OS and hardware to run such software on. I have a low motivation to put a 32-bits Windows XP machine, that takes ages to boot, in a safe, with a copy of DPP, just to make sure...

hgraf said:
Personally, I'm not worried about it, there are SO MANY images out there using Canon's RAW format I don't see any software "dropping" it any time soon.

As for DNG, while the image data might be losslessly captured, there are other elements of the RAW file that may not, meta data being one thing. I'm not sure what else is in a RAW file that DNG doesn't store, but I'm sure there's something.
Click to expand...

Yeah, thanks, this is really on the minus side of DNG.

gargamel
 
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