RAW vs. DNG

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The debate on whether to import and post-process files as RAW or as DNG (Digital Negative) is almost as heated – and opinionated – as whether to shoot with Canon or Nikon. The long and short of it is, “it depends,” and “it’s up to you.” There is no “right” answer.

RAW files are digitally unprocessed image files that come straight from your camera. They have no adjustments or alterations made to them so that when you load them into your post-processing software, you have the utmost of flexibility in altering things like exposure, white balance, and the like. The RAW “recipe” varies between camera manufacturers, which means that the file formats are not universal between software brands and versions. For example, when I upgraded from my Canon Rebel XTi to my Canon 7D I also had to upgrade from Photoshop CS3 to CS5, because CS3 didn’t support the 7D’s RAW files.

The DNG file type is very similar to a RAW file in that it is an unprocessed image file that can be manipulated and altered. It is an image standard developed by Adobe and is intended to be a type of “generic” RAW file that is universally compatible regardless of the camera brand. Upon import, the RAW files that your camera took are converted into the DNG file format (so, the RAW files are still on your camera’s memory card until you format it). More software programs can read DNG file formats than proprietary RAW file formats. For instance, if my files had been imported in the DNG format instead of RAW, Photoshop CS3 would have been able to read the files from my 7D.

Many photographers choose to convert their RAW files to DNG upon import for the following reasons:

- DNG files are smaller than RAW files (by around 15%). This is because “unrecognized metadata” (such as focus points and picture control settings) is stripped from the file.
- Any changes and adjustments made to the file are written to the DNG file itself, rather than appending a “sidecar” .xmp file which contains all of the changes.
- Photographers anticipate that the DNG file format will be supported farther into the future, minimizing the risk of obsolescence and incompatibility with future programs.

Many photographers choose to use RAW for the following reasons:

- RAW files open, import, save, and edit more quickly because there is no need to convert to another file format during the process.
- RAW files contain more metadata specific to the camera and the shot itself, which is important to many photographers.
- DNG files are not compatible with some brand-specific imaging products and solutions.

It is important to note that there is no difference in image quality between a DNG and a RAW file.

Personally, I have worked with both. I tend to stick with the RAW file format because I like lots of metadata, and it’s easier for me to go back to original RAW files when I want to try multiple editing techniques on a single image. There are many schools of thought on whether to stick with RAW or import to DNG. I found a handful of articles that you might find to be helpful in making your own decision.

Helpful Resources:

- To DNG or not to DNG at Lightroom Killer Tips
- RAW vs DNG – A Practical Overview of the Differences, a video by SLR Lounge
- A primer on the Digital Negative file format by Adobe.
- Understanding Digital Raw Capture by Adobe.

Do you have an opinion on whether to use RAW or DNG? We’d love to hear your thoughts in the comments or on our Facebook Page.

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  • http://twitter.com/BarryCPearson Barry Pearson
  • http://twitter.com/ohnostudio ohno studio

    You wrote “- DNG files are smaller than RAW files (by around 15%). This is because
    “unrecognized metadata” (such as focus points and picture control
    settings) is stripped from the file.”

    Unfortunately that’s not entirely true. The Raw files from my Leica D Lux 4 with an RWL extension are about 14MB I think. When I converted to DNG with the “preserve camera data ” option they weighed in at 45MB or so. That’s just crazy.

    And now yet another quirk. I used Bibble for many years. Corel bought them and now it is AfterShot Pro. It’s great, like Bibble on steroids. But right now, it will not open converted DNG files. It will open native DNG that the bigger Leicas produce out of camera, but not conversions like the few I tried with my Nikons. I am sure this is something Corel will iron out. I am sure others have already written Corel but I’ll do it too as I really like the product.

    So even there have been the claims of “seamless: and all the rah-rah by the OpenRaw people, it’s doesn’t work faithfully.

    Here are a couple of posts about AfterShot in case you are interested – this one pretty much general comments

    http://ohnostudio.com/2012/01/bibble-is-now-corel-aftershot-pro/

    And this one about some nice work it did in recovering a pretty much crap and blown image

    http://ohnostudio.com/2012/01/iris-on-black/

  • http://twitter.com/BarryCPearson Barry Pearson

    Are you talking about “Embed Original Raw File”? This puts the whole raw file inside the DNG, and inevitably results in a large file. Its purpose isn’t to add metadata; it is to enable you to extract what the camera delivered unchanged later.

    DNG files are often (not always) smaller than original raw files; this is because they compress the image data better, not because of a reduction in the amount of metadata. (The whole metadata is unlikely to be anywhere near 15% of the size of the original raw file).

  • Rob Ives

    When I tried DNG it didn’t support embedded GPS. Is that still the case?

  • Mi_bali

    Food for thought…but if you are a purist no question, no debates. Go like your heart….RAW

  • http://jimmartinphotoblog.blogspot.com/ Genesis Jim

    The reason I import files as RAW (Sony’s *.ARW) files is two-fold. If you are browsing your pictures with your computer’s “Explorer”, you won’t be able to see thumbnails of DNG files, but there are RAW-viewer programs that allow you to do so. I don’t think there are any for DNGs. Second, if you import your files as DNGs in Adobe Lightroom and make a second copy at the same time (to a different HDD), LR will do it but the second copy will be as a RAW file! First of all, that seems to make no logical sense (if I want DNG, I want DNG, dang it!). Second of all – and this was the clincher for me – if one HDD crashes, your LR catalogs will not automatically associate all those links to DNGs from its database with the backed-up RAW files. Last year when I lost a hard drive this is exactly the problem I had, so I had to reassociate all the files in each individual folder in LR with the new one on my backup drive. 

  • http://twitter.com/rinconslr Óscar Martínez

    I do not care RAW obsolescence because there will always be software for converting between formats.
    In any case, it would be desirable to go for a non-proprietary open standard

  • http://pallopanoraama.blogspot.com/ Janne

    There’s also option of  linear or demosaiced DNG which is *not* a lossless process if coming from a raw camera file.

  • http://twitter.com/Larryphoto Larry Lourcey

    Maybe its just me, but I predict that DNG will go the way of Beta videotape eventually.  RAW just seems too established.