Photography Work-Flow: Archival RAW Format?

While I haven’t fully figured out the answer to my previous photography related question (on the archiving, not simply backing up, of photos) I am getting closer.

I have a question about the archiving of RAW files.

One of the commenters, Damon Lynch, provided some insight to a collection of best practices (“DPBestFlow”) developed by the Library of Congress (an organization that I trust when it comes to the process of archiving materials). [He also linked to a Free Software tool he wrote to quickly download and backup photos from your digital camera, Rapid Photo Downloader.]

Just your daily photo of Rowan.

The DPBestFlow site introduces me to a file format that I was previously unaware of, DNG, or Digital Negative. The DNG format, created by Adobe, is a ‘universal’ RAW format with an open (ie: not patent encumbered) specification. This is in stark contrast to the slew of proprietary formats that are camera maker specific (closed formats that might include encrypted portions) such as NEF (Nikon’s) or CRW/CR2 (Canon’s).

There was even an initiative to garner wider adoption of open standard RAW formats back in 2005 started by Juergen Specht called OpenRAW (Wikipedia).

Now, I am a huge proponent of open formats and standards (obviously?) but my question really is:

  • Is it worth it?
  • Should I convert all of my Nikon RAW files to DNG?
  • If I do, should I save the original NEF files “just in case?”

Also, why am I not simply reading the many discussions already had on this topic? Because I want to get the uniquely free software view on the issue.


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  1. Do you have to use an adobe tool to convert them to DNG? If that’s the case I wouldn’t consider it very open. Either way you can always go .NEF => DNG if you HAD to someday (Due to software changes that may no longer support older cameras) but you can never go DNG => NEF.

    I’ve got 3 years (Well over 100k photos) in .NEF. Hard drive storage isn’t that expensive.

  2. CHDK uses DNG as their RAW format, i don’t know if it’s worth it and which tools are available but at least there’s someone using it

  3. @Edward: No, you don’t have to use Adobe’s tools to do the conversion. Digikam (which uses libraw) can do it for you. And, this isn’t a question about harddrive space.

    @hello: Yeah, and some camera manufacturers even use DNG as their native RAW format, see:

  4. Greg,

    Although it’s not quite ready for prime time, Dmedia is meant to handle photos also, and is able to automate your backup process, working between multiple computers, etc. You might checkout the Dmedia import workflow:

    Personally, I’d definitely keep the original RAW files.

  5. @Jason: Thanks!

  6. Personally, Greg, I’d make sure to keep the camera-specific raw files. I remember reading something about this some years ago. Although using the DNG format is convenient, you may still suffer losses in the conversion process.

    The purpose of the camera-specific raw file is to dump the raw sensor data that the camera provides, thus allowing the digital equivalent of the film negative. By converting to the DNG, you are doing the digital equivalent of making a copy of the negative, and although the equipment may allow for a very good copy, there are still losses in the process.

    Also, for what it’s worth, I’ve found JPGs to give good results not only on screen, but also at the one-hour photo lab. A 2633×1881 crop of a JPG I had printed very nicely for me at 10×8.

    Keep the camera original raw files. I honestly wouldn’t suggest using the go-between of the DNG format unless a submission or program requires it. I also suggest using UFRaw, if you don’t already, as part of your digital darkroom setup.

    Good luck,


  7. @Henry: Thanks!

  8. […] Photography Work-Flow: Archival RAW Format? […]

  9. I have started focusing on archiving my old digital photos. I have some that go back as far as 2000. In total, I am looking at about 1TB of digital images. Most are Nikon NEF Raw with a .JPG copy. Older images are Canon raw formats or .TIF.

    I looked at converting my .NEF to .DNG, but that still assumes Adobe is going to still be around. Besides, .DNG is not widely adopted. OpenRAW was an interesting format, but not enough adoption to view the images. I ended up keeping everything in their native raw plus a .JPG full resolution copy. Until the world and manufacturers can find a true native raw format, keep your images in two formats.

    My simple rule, Native Raw + Jpg just in case.

  10. @Chris: From my understanding, the fact that DNG is a published spec means I don’t care if Adobe is around in 100 years (when my Rowan’s kid’s kid cares about Rowan). That is why the Library of Congress, through that collaborative, recommends DNG over the native but opaque/proprietary formats from the camera makers.

    All of the software I use can read/open/edit DNG files, so that isn’t an issue, but there is the question of whether or not I actually am losing any data in the conversion, and whether or not it is significant enough to care about. I’ve seen a post where someone does a fancy diff between the native RAW and the converted DNG and there are some (minimal?) differences.

    Oh well, for now I’ll save the cpu cycles and just still with NEF+JPG.

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