Long Term Storage Format....

[Meadster]

This thought has been in my mind lately and I think I am doing the "right" thing for the future, but I thought I'd throw it out o all of you as there are many voices on here I really respect. Here goes...

I currently shoot in raw with my Canon 50D which produces "cr2" RAW files. When I download then I convert them to "DNG" files and they stay that way for the purposes of archiving. My question is, Should I use DNG as my long term archive format, or should I convert them to PSD or TIFF. I like the idea that DNG's have all the RAW information and can be reprocessed later if I need to. While no one can know what format will be preferred 20 -30 years from now, I'd be interested in hearing what others here do for long term archiving .

FYI - once I process an image, I save it as a PSD to maintain layers, etc.

Thanks for the feedback!

[jdepould]

It's a problem no matter what format you use. While the DNG spec is public, it isn't open-source. So Adobe can do whatever they want with it, or it could evaporate if the company were to fail. Obviously, you want something uncompressed (or losslessly compressed), so that doesn't leave you a whole lot of options.

The camera makers are (almost) all centered on their own proprietary formats--Leica being the exception. It'll probably take something big to knock some sense into them. The downside is that converting to DNG doesn't preserve 100% of the information, since the camera companies don't publish white papers on their formats. There is guesswork involved--this is why you'll see differences in images depending on the program used.

Basically, your system right now is about as good as any other. There isn't a good way to do it right now.

[Algernonep]

I convert to DNG also... but I also keep the RAW file that comes out of the camera. To me that works for me. I feel safe that I have DNG and a RAW file back up. Jdepould is right. There is not really a good way of doing it right now!

[inkista]

Originally Posted by jdepould

It's a problem no matter what format you use. While the DNG spec is public, it isn't open-source. So Adobe can do whatever they want with it, or it could evaporate if the company were to fail. ...

Just a slight tweak on some of the assumptions in the statement above. The term "open source" means program code for an application where you can actually look at/modify the source code and recompile it. This is used to describe programs/applications, not file formats.

The DNG standard is open. The file format itself is freely and fully documented and you can get the full spec of the current version here. While it is true that Adobe can do with it what they want, they have not yet ever failed to publish the full spec of the format, and have repeatedly stated that they're more than willing for a standards body, such is ISO, to take it over.

If Adobe were to fail, and all their software to disappear and stop working, the standard is still there, and you can theoretically write a program or use a byte editor of some kind to can-open your image back out. TIFF is probably more accessible directly than DNG, but DNG is based on TIFF. So DNG is relatively safe from company/application-reliance, in the way that, say, MS Word's .DOC format, or Photoshop's .PSD format is not.

Where the real danger lies in using DNG is that it is not a formally adopted open standard in wide use. TIFF and JPEG are. DNG is still only really championed by its creators, Adobe. And while some cameras use DNG as their RAW format, Canon and Nikon continue to use their own proprietary RAW formats in order to support extending feature sets.

Right now, there is, as everybody's saying, no bulletproof/future-proof archive format. But TIFF may be the closest, followed by DNG.

[jdepould]

As an aside, most raw formats are TIFF-based, no?

Edit: I should've gone looking for these the first time around, but Luminous Landscape has a few articles covering this stuff:

http://www.luminous-landscape.com/essays/raw-law.shtml
http://www.luminous-landscape.com/essays/raw-flaw.shtml
http://www.luminous-landscape.com/es...awtruth1.shtml

[inkista]

Yup. You can think of RAW as TIFF + metadata.

RAW differs from DNG, in that most of the file formats are proprietary, closed, and ever-changing. There's usually a new version with every camera, because some of the metadata will be there to support the new features of the camera. Nikon (and probably Canon), iirc, actually encrypts part of the RAW file information to try and keep some implementations from being reverse-engineered.

[Henry Wilt]

Sorry if this is a stupid question but i've only just started shooting in RAW and was doing a little research on DNG at the weekend (mainly because I thought the reason for converting was to reduce file size which apperently is not the case) so have very little knowledge of the formats.
Are you saying that it is not a good idea to archive the files in the original CR2 format?
If not and DNG is a better option, as they are bigger (so I read), is it safe to use some form of file compression to reduce the amount of disk space they will take up?

[Bluenoser]

Originally Posted by Algernonep

I convert to DNG also... but I also keep the RAW file that comes out of the camera. To me that works for me. I feel safe that I have DNG and a RAW file back up. Jdepould is right. There is not really a good way of doing it right now!

I'm in the same boat - convert to DNG but also save RAW files.

I wouldn't go as far as to say there aren't any "good" ways of doing it, think there are plenty of good ways of doing it now, just that there's a lot of different ones.

[Sime]

Originally Posted by Meadster

This thought has been in my mind lately and I think I am doing the "right" thing for the future, but I thought I'd throw it out o all of you as there are many voices on here I really respect. Here goes...

I currently shoot in raw with my Canon 50D which produces "cr2" RAW files. When I download then I convert them to "DNG" files and they stay that way for the purposes of archiving. My question is, Should I use DNG as my long term archive format, or should I convert them to PSD or TIFF. I like the idea that DNG's have all the RAW information and can be reprocessed later if I need to. While no one can know what format will be preferred 20 -30 years from now, I'd be interested in hearing what others here do for long term archiving .

FYI - once I process an image, I save it as a PSD to maintain layers, etc.

Thanks for the feedback!

Why not just archive the CR2's??

[BigFuzzy]

Originally Posted by Sime™

Why not just archive the CR2's??

Yeah, what he said.. can you imagine a time where there will be nothing to read your CR2s? Maybe I'm naive, but I can't. I'd be more concerned with HOW you're backing them up than in what file format... this coming from a guy with 5HDDs and Mozy as back up due to paranoia.