Adobe DNG – The Future is NOW

To the modern digital photographer, the Raw data from the camera is the modern day equivalent of the traditional photographer’s negatives or slides. Everything we need to create stunning final images is provided by the single simple file, regardless of its format – be it .NEF, .CRW, .CR2, .PEF; the list goes on and on. All major DSLR’s can export your images as Raw sensor data, otherwise known as a Raw file.

Shooting Raw benefits both the photographer and the final image, as all recorded information at the time of the shutter release is held as is, with minimal processing. However, the success of the Raw format has engendered a few problems, primarily being that every camera manufacturer has its own propriety format incompatible with other cameras, not to mention their other models.

Luckily, Adobe stays on top of new camera releases and enables Lightroom and Adobe Camera Raw with the data needed to process each of these differing formats. However, if you own more than one camera, you will be inundated with differing Raw files that you have to wrangle into some form of organization. Thoughts also linger on what may happen to the propriety formats if something happens to the manufacturer or they simply cut support. Heck, I have files from an old Kodak DC25 point and shoot that can no longer be decoded easily as the Kodak provided software is no longer available, so I know that this situation can occur.

The good news is that Adobe has offered to the public a great solution that anyone can use; software developers, camera manufacturers and photographers. This solution is Adobe’s DNG format, also referred to as the Digital Negative format. DNG is a wrapper file that can contain either mosaic (Raw) or linear (Tiff or Jpeg), include extensive metadata, and function with Lightroom or ACR as a normal Raw file. Once a Raw file has been converted to DNG, any Adobe product that can render Raw files can handle it as well as many other products, including Apple’s Aperture.

Once you convert a file to DNG, you know that it will work well into the future, regardless of changes in the software and hardware landscapes. Adobe has opened the DNG specification to all other manufacturers and developers, so DNG is not a proprietary format, it is an open format. DNG is even included in the TIFF-EP ISO 12234-2 Standard, as DNG was originally based on and compatible with the TIFF-EP spec. DNG’s status as an open will ensure DNG’s use well into the future, hopefully even allowing the format to break the third wall and become natively available from Nikon and Canon (Pentax and others are already there).

But enough waxing poetic about DNG, you can clearly see I like it. Let’s really get into why you should be using DNG if you are not already and how you can include DNG in your image workflow.

DNG can help make the incompatible, compatible.

Previously I mentioned that a Raw file is analogous to a film negative. In many ways that is true, but the differing formats of Raw files precludes Raw data from truly being the digital equivalent of a film negative. Imagine if you had to treat a Kodak negative differently than a Fuji negative to get a print made, it is a ludicrous concept. Converting your images from differing camera bodies to DNG will standardize your Raw data. Once converted, you know that your images will open right in a litany of applications.

Another benefit of DNG, by using the DNG Converter as covered previously here, is that you can use the Raw data from the latest cameras before Lightroom or ACR are updated to include native conversions. Every hot, new camera has a time period between release and when Lightroom natively handles the Raw files, but almost always DNG converter can reprocess these incompatible Raw files into DNG’s that are readily usable in your current version of your software. DNG can help make the incompatible, compatible.

Since the DNG specification is openly available, support for this format is only going to grow. Sure the big names may hold out, but eventually as more software and cameras use DNG it will slowly become a standard. From my point of view, it is best to join the bandwagon now and convert my Raw files now, so I am ready for the future as DNG becomes more prevalent. As it is, DNG capable software is on every computing platform from Windows and Mac to Linux and BSD.

No matter which platform you use now, or may use in the future, you will be able to utilize your DNG files. With DNG’s open nature support is only going to increase. Anyone can get the DNG specification for free and use it as they deem worthy, want to see for yourself? Its right here for you. DNG is an open file format and mainstream use is only going to increase in the future.

DNG has support from 3rd parties, both large and small.

Further considering DNG’s open nature, it is amazing the software that can now natively support DNG. Obviously Adobe supports DNG, but a growing list of 3rd party manufacturers and applications have products that can use or create DNG files. Apple’s Aperture 2 and iPhoto both support DNG. Corel’s Paint Shop Pro can do DNG as well. The open source program dcraw supports DNG, bringing DNG capabilities to a vast array of applications that utilize dcraw as their rendering engine, including the illustrious GIMP. Lightroom competitors LightZone and Capture One support DNG natively. Even Picasa supports DNG.

Considering the vast array of 3rd party support, you will always be able to use your DNG files, even if you were to suddenly wake up and say “I am never using an Adobe product again.” The list of software that currently manages DNG is huge, but if you are interested, Barry Pearson has compiled an exceptional listing of software and hardware that supports DNG. The bottom line here is simple. DNG has support from 3rd parties, both large and small.

So far we have only looked at big picture reasons to use DNG. Maybe that is not enough to convince you to integrate this great tool into your workflow. So let’s look at some local reasons to use DNG. I will start with file size. Raw files have a way of just eating up your hard disk space. As megapixels grow, so does file size. DNG can help to tame the file bloat beast. Inside the DNG specification, and in turn DNG applications, lossless compression is introduced.

As it is, some camera manufacturers include lossless compression in their native format, but many do not. DNG conversion will normally shrink your Raw files a bit.  On my Canon 400D’s 10 megapixel files, I usually get about 5-10% compression. That little bit adds up across many photo sessions. DNG will shrink your Raw files down, without compromising your data.

Speaking of disk clutter, when working with normal Raw files in Lightroom or ACR, you will discover that you quickly litter your disk with a multitude of annoying little .XMP files. Every image you edit, when metadata is written to disk, will have a corresponding .XMP sidecar file created to carry that image’s metadata and develop settings. Not a huge deal normally, but annoying. DNG eliminates the need for .XMP sidecars, as DNG is designed to contain all metadata directly within the file itself.

DNG eliminates the need for sidecars, and keeps your image and edits in one place.

This is great for backing up, as you don’t have to worry about all the .XMP files. It is also great when you have to shoot a raw file over to a client or employer. If you send a DNG, all your edits are built right into the file. If you send a regular Raw file with an .XMP, the recipient may not even copy over the .XMP, leading their view of your work to vary greatly from you own vision. DNG eliminates the need for sidecars, and keeps your image and edits in one place.

Of great importance to me, DNG also allows me to bring my film scans into a Raw workflow easily. If you ever read my blog LifeInDigitalFilm you know I am heavily into shooting film still. I do a lot of scanning, but my goal is to treat my scans much the same as I would a Raw file. I edit all my scans in Lightroom and ACR. Converting TIFF and JPEG files to DNG offers me three benefits.

First, my original scans that I convert to DNG will stand out from all other TIFF and JPEG files on my hard disk. Since my originals are converted to DNG, the difference is readily visible in the file manager and Photoshop will automatically fire up ACR when I am opening a scan DNG. Second, DNG protects my original scan data. I cannot accidentally overwrite a DNG like I can a normal TIFF. My original TIFF from the scan is safely embedded in the DNG file and treated much like Raw data from then on.

Finally, the compression present in DNG makes a huge difference in my scan size. Even compared to the standard TIFF compressions available, DNG squeezes my scans into a smaller footprint, while enabling all the metadata features inherent in DNG. DNG can protect your TIFF and JPEG files when editing in other applications, a layer of protection to prevent accidental file damage by treating regular images like Raw files.

Finally, one of the best features of utilizing DNG is seamless integration between Photoshop, Bridge and Lightroom. Regardless of if the DNG is made from Raw data or a TIFF, the file will move smoothly between these core Adobe applications and carry your develop settings and metadata between each application. DNG can help you stay organized and get the most out of your investment in Adobe software.

Hopefully, I have given you a few compelling reasons to make the switch from closed, propriety Raw files to the open and flexible DNG format. Now to actually carry out the process.

If you have a lot of Raw files about, and they are not in Lightroom already, you can choose to use the Adobe DNG Converter or convert on import into Lightroom.

If you already have your propriety Raw files imported into Lightroom, you can convert them right from within Lightroom. Simply click on Library from the toolbar and select Convert Photos to DNG…

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This will bring up the conversion dialog where you can choose your DNG settings.

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If you want to trash your propriety Raw files upon conversion, you can check the box by Delete original after successful conversion. If you are panicky about getting rid of your original Raw files, you can choose to embed the original Raw file into the DNG as well by selecting Embed Original Raw File, although you will increase you file size drastically. Click OK and Lightroom goes to work.

You can also use this method to convert TIFF and JPEG files to DNG. Simply make sure Only convert Raw files is not checked. Lightroom will then wrap up all your linear raster images into the friendly confines of DNG.

You can also convert single files from their proprietary Raw format right from Adobe Camera Raw. Lightroom and DNG Converter work much better however, as they can do entire folders and libraries at once. ACR is a bit limiting as it can do one at a time.

Simply open you Raw file in ACR. Once it is open, select Save Image…

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This opens the Save dialog from within ACR.

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At the bottom of the dialog, simply change the Format to Digital Negative. This will change the window to show the DNG options.

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Make your selections and click Save.

If ACR is configured to open TIFF or JPEG files, you can then save them to DNG from ACR.

There are other ways to convert to Raw files to DNG, but these are the basics. If you are interested in making DNG files directly from image scans from you scanner, definitely check out VueScan, as it is the only scanning software I have found that supports output to DNG.

Again, hopefully I have either opened your eyes to the benefits of DNG or have reinforced your decision to have done so already. If you have any questions or comments about DNG, the use of or conversion to, feel free to sound off in the comments.

Michael W. Gray

Michael is an artist who has been working for years to blend technology with traditional film photography.

COMMENTS (19)
  1. I used to have the same view as you…. but then I noticed that my sRAW files from my 5D MKII which are only ~12MB (CR2s) became 25MB DNG. So I stopped using DNG and my workflow is also faster now (No lag when converting)

  2. Hi,

    I wanted to switch to DNG but the major flaw if you don’t include your original RAW file in the DNG is that you can’t use new software like DxO Optics 6 with a new raw converter that can improve the quality.
    http://www.dxo.com/intl/photo/dxo_optics_pro/new_in_V6#excellente

    I think that the DNG is great for backup, I will convert all my nef raw file the day they will not be supported with the next raw converter version.

    Whaly

  3. the different raw-formats are a pain. hopefully dng is the winner!

  4. Canon’s sRAW format does indeed have issues with DNG. However this is due to the way that Canon creates their sRAW files and the fact that DNG currently has no specification to contain sRAW files.

    This is due to the lossy compress that is applied to the orignal RAW data from the camera’s sensor that is downsampled to create the sRAW format. The camera renders 1/4 less “RAW” pixels in the sRAW format by downsampling from a 4×4 pixel grid, duplicating the color data equally across the 4×4 grid then compressing.

    Converting sRAW to DNG essentially de-compressed the sRAW into a standard RAW file, although the data lost is still lost. The RAW image is recreated by expanding the single compressed pixel back into a 4×4 grid, although the grid contains the same color information across as the original pixel.

    When I rent a 5DmkII for weddings I never shoot in sRAW, for this reason and the fact I hate to discard information. Due to the extensive processing a sRAW file recieves, I don’t consider it a RAW file myself, so I don’t use it. Although I can see the benefits of using sRAW, it just doesn’t suit my needs.

    If sRAW suits you workflow, then DNG is obviusly a bad idea currently. Although since sRAW is antively handled in Lightroom and ACR I suspect that the DNG specification will be updated to include the capability to convert sRAW properly, possibly even including the capability to compress standard RAW files similarly, although I don’t personally see a need for adding in that feature. Adding in sRAW rendering is a must do for DNG in the future.

  5. Every time the subject comes up I have to reply with the reason why I DON’T convert to DNG. Backups. I only have to backup the RAW file once (to a hard drive, I don’t do discs… I’d never see the end of the stacks!). I can make edit after edit in Lightroom and all I have to do is backup the catalog and as a precaution, the xmp files (does anyone backup ‘files’? Or do like me and backup the whole ‘folder’? Sidecars aren’t really an issue for me.)

    After editing a few thousand photos, I’d rather copy over a few thousand 7-15kb files instead of a few thousand 7MB files. Until there’s a convenient way to do bit by bit backups, DNG just doesn’t offer me anything worth the trouble.

  6. Bit-level incremental backup/copy/sync has been native in OS X for years. This is also true for numerous consumer grade backup utilities for both PC and OS X platform(s).

    This is an easy mitigation strategy for the issue you described.

  7. Dear Michael W Gray,

    Thanks for the great article. I have a similar one, with a video tutorial on the three ways to convert Raw files into the DNG format, here that might help your readers.

    http://thelightroomlab.com/2009/06/converting-digital-camera-raw-files-to-the-dng-format-using-adobe-photoshop-lightroom/

    I too am a big fan of the DNG format and have been using it store my Raw files for many years. In my workflow, the smaller file sizes and the embedded “xmp sidecar” information are huge advantages. DNG conversion is an essential step in my workflow and one that really should be happening inside of my camera. Its high time that we photographers demand this feature from the major DSLR manufacturers.

    Likewise, I think the day is coming when the highest end stock agencies and magazines are going to only accept DNG Raw files. Grant Gunderson, publisher of The Ski Journal, is already leading this charge. His magazine only accepts “DNG Raw files” with “meaningful metadata.” You can see their full submission guidelines here.

    http://www.theskijournal.com/pages//information/submission-guidelines

    Clearly I am a big fan of DNG conversion for Raw files but I do not think converting TIFF or JPEG files into this format makes sense. This move doesn’t make sense to me since these files do not become “raw” just because their extension changes from .jpg to .dng etc. Tif and Jpeg files are already in a universal format and they already handle metadata without the need for an external sidecar file.

    In my opinion, turning non-raw files into DNG is not a good idea. The conversion here does nothing except create needless confusion about which files were actually captured in Raw and which files were not.

    Thanks again for this excellent post.


    David Marx
    http://www.thelightroomlab.com
    http://www.davidmarx.com

  8. Brandon, thanks for the helpful and well written article.

    I think you made a good case for converting to DNG but there are some good reasons not to.

    Many manufacturer specific (e.g. Canon and Nikon) raw converters won’t process DNG files. There are other 3rd party raw converters that won’t read DNG. Just be sure you don’t want to use these down the track. The potential file size advantage of DNG quickly disappears when keeping original raws tucked away just in case.

    Another is the backup situation mentioned above. Mac OS X Time machine is a good example. I’m not sure what the deal is in OS X 10.6, but I know in 10.5 Time machine would re-backup an entire file even for minor changes. Perhaps this was fixed in 10.6. Perhaps not.

    Of course, this backup issue may not be relevant to all users and can certainly be mitigated but one could argue this is an advantage to side-car files and a disadvantage to DNG. At the very least something to keep in mind.

    I hope DNG eventually becomes the standard but am personally not convinced about converting for now. The advantages are very likely not worth the trade offs for me now. Perhaps I can be convinced though 😉

  9. @David Marx Thanks for the comments, I’m glad DNG works well for you and we are in agreement on the benefits for RAW files.

    As far as TIFF files go though, I am still a big fan of converting my original TIFF scans to DNG. I have a variety of reasons for this, and I find I only need to convert my original scan to DNG to fit my workflow.

    First, I scan in my negative and slides in as 48-bit files in the ProPhoto color space. This leads to fairly large scans, and I find DNG compression of these files to be better than the standard TIFF compressions available.

    Second, I treat these scans as RAW files in my workflow, although I am fully cognisant of the fact they are still linear files. This sets aside my scans from derivative TIFFS, so that I do not overwrite or alter the original files. To me, these first generation scans are the film eqivalent of RAW files in my workflow, so DNG fits.

    As the filename for the DNG matches the standard output format for my scanning program, VueScan, I can easily differentialte scans from true RAW files. To further aid in identification, scan DNG files are stored in a different folder on my working drive and in a library just for scans in Lightroom.

    The extended benefit of wrapping my TIFF scans up in DNG is that they are protected in any workflow. Regardless of wht application I may use, the file will either be open from ACR or other DNG converter, or I will have to re-export back to TIFF for non-compliant software (which I don’t use anyways). This protects my original scans from being overwrote or modified, which means a lot to me, as scanning can be time consuming, and I have a bad tendancy to accidentally overwrite my original occassionally. TIFF DNG helps me avoid that mistake.

    I understand this may not work for everyone, but it works awesome for me. I am currently starting a series on film scanning for a Lightroom/ACR workflow on lifeindigitalfilm.com, and DNG for scans is an integral part of my plan, primarily for the reasons listed above. Data protection and differentiation make a huge difference to me, so I felt I should share my view on linear images in DNG format.

    Also note, some DSLRs, primarily the Foveon-based Sigmas, when converted to DNG are no longer truly RAW files. DNG is specified to contain bayer-matrix based RAW data. Since Foveon is not based off the bayer-matrix, but is instead a R+G+B format, it has to be converted to a linear file on conversion. So DNG conversion for those cameras essentailly convert their RAW format to a linear file, much like a TIFF. Just some info I stumbled upon in the past day I felt should be noted.

  10. Whoops just want to correct my earlier mistake and give thanks to the actual author of the article. Thanks Michael W. Gray!

  11. I know this is where I went wrong last time and I forgot to click on the remove the originals and ended up with both the original RAW & the DNG files – very confusing and twice the space taken up than I wanted.

    For some reason I feel that by using DNG I don’t have the same functionality of the RAW data within LR or PS (I know, I know)

  12. DNG is the way to go for back up and storage but its slow to work with while editing!

  13. I started converting to DNG soon after I switched to lightroom a few year ago. I don’t use any other 3rd party tools, so no compatibility issue there. Love no xmp files (use rsync for incremental backups anyway so size doesn’t matter).

  14. Very well-written article, Michael. I think you’re more enthusiastic about DNG than I am, but I did convert to an all-DNG workflow several months ago. The only annoyance I have is that importing files takes much longer because of the CR2-DNG conversion, but it’s not enough of an annoyance for me to go back. I was concerned about backing up the whole file even for a small change (I use Chronosync, which has to back up the entire file), but even my nightly backups over 802.11n have never failed to complete by the time I woke up.

    Has anyone tried moving DNG between DAM apps, like between Lightroom and Aperture? Do they keep any of the edits made in the “other” app?

  15. 1- How does one convert to dng fully processed Raw files and keep the xmp sidecar info intact in the DNG??

    2 – If I send a DNG to a processor and after all the work is done they send finished file back to me will LR show the edits or will it show everything at zero in the develop module?? Reason for this question is, when I 1st started out over 30 yrs ago I simply dropped my film off for processing and proofing due to the fact that I was shooting way too much for me to do it myself…and I am hoping that after a several year hiatus I will once again be shooting weddings every sat and sun. and throughout the week plus portraits in between times and that will pretty much nullify my ability to keep up on the processing.

    Thanx

    1. 1 – To convert standard RAW+XMP w/ edits to DNG, simply export to DNG. (Use contextual menu -> Export… -> Choose to export the files as DNG by changing the File Setting to DNG) This will rewrap the RAW+XMP to a DNG with all edits intact.

      If you are working with a DNG file, you can use the same method to make a one-off file with edits, or simply write edits to metadata and use the master DNG.

      2 – Generally all the edits will be included with the DNG file. There are a few tricky ways to hide that, but most retouchers would never use it, as it makes the DNG file non-compliant and ususally a TIFF wrapped up in DNG. You may not have the History tab populated with their procedure, but all adjustments will be visible in the Develop Module editing panels.

  16. Art,

    #1 – In our workflow we no longer need/use XMP files since all of the edits in LR and corresponding Metadata is included in the DNG file(s).

    #2 – I may have answered #2 with #1 above: ll of the edits in LR … is (are) included in the DNG file(s).

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