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No see any overall file reduction with DNG

Discussion in 'Image Processing' started by YantaYo, Mar 22, 2014.

  1. YantaYo

    YantaYo Mu-43 Regular

    Apr 18, 2012
    Hi all,

    Beta testing migrating from Aperture to Lightroom. Supposedly one of the main benefits of importing to DNG is a 10-20% smaller file size. I imported 120 Olympus Raw .ORF files . Original fold size was 1.73GB. The import DNG folder size is 1.74GB. I have Lightroom preferences for DNG set to Camera Raw 7.1 and later and JPEG preview set to None and Embed Fast Load Data checked (Embed Fast Load Data unchecked the folder size is 1.68GB). On import I have Build Previews set to Minimal.

    I am just not seeing any real size decrease of the imported images. Without Embed fast load data the file size reduction is just 3%

    Any thoughts?
  2. Any size benefits from converting a camera's native raw files to DNG only come about when the raw file hasn't been efficiently compressed in the first place. An example of this from a few years ago was Samsung who didn't compress their raw files in-camera and converting them to DNG reduced them from about 50Mb down to 20Mb.
  3. YantaYo

    YantaYo Mu-43 Regular

    Apr 18, 2012
    That makes sense. Olympus states Orf files use lossless compression. Interesting Scott Kelby's Lightroom 5 book globally states there is a 10% to 20% file size reduction when going to DNG. I guess he does not know everything. I'll have to find out if my Nikon NEF files are already compressed as well.

    I'll have to think on converting Raw to DNG. Reduction in file size was one of my main reasons for this.

  4. dhazeghi

    dhazeghi Mu-43 Hall of Famer Subscribing Member

    Aug 6, 2010
    San Jose, CA
    Unless you only plan to use your RAW files with Adobe products, I wouldn't convert them to DNG. Some other software (notably Olympus's own Viewer) don't support DNG, while others (e.g. Apple Aperture) handle it differently. You can always convert to DNG later on if you end up with some software that requires it.
  5. brettmaxwell

    brettmaxwell Mu-43 Veteran

    Dec 8, 2012
    Yes, some raw formats are already quite efficient. I remember when I had an X100 every single file was exactly the same size (about 19mb) and turning them into DNGs would average probably 50% reduction.

    Aside from compression, there are pros and cons to DNG:

    -easy to check for corrupted files in your archive (Library>Validate DNG Files)
    -adjustments are written into the file
    -lossy compressed can bring file sizes way down (helpful when using a D800 for casual shooting!)

    -pretty much locks you into Adobe, it's an open standard, but they're the only ones really pushing it
    -takes time to convert to DNGs
  6. YantaYo

    YantaYo Mu-43 Regular

    Apr 18, 2012
    I am still on the fence on whether to import as DNG. Right now I am exporting my aperture library (includes the raw NEF and ORF files) to an external hard drive. I might keep all these files on the external while I keep the Lightroom photographs on the internal hard drive. There are numerous RAW pictures I might want to see how they look in Olympus Viewer. For that it would just be easier to export the raw file out of Lightroom instead of finding it on the external. Anyone have a dart board to throw a dart at to make the decision- or a Ouija board.
  7. bassman

    bassman Mu-43 All-Pro

    Apr 22, 2013
    New Jersey
    The Bassman
    DNG is just another format, and I wouldn't convert unless there's a very good reason. Saving a few bytes wouldn't pass the test for me when multi-terabyte drives are reasonably priced. LR makes the underlying file format pretty irrelevant.
  8. These numbers may once have been about right but not any more. My E-M5 and E-P5 show no size reduction to the raw when converting to DNG, and my old Sony NEX-5N was the same. On the other hand the raws from my Canon G1X and Samsung NX300 both reduce by up to 10% when converted to DNG.

    I once considered converting all my raw files to DNG for consistency but ultimately I didn't see any real benefit to it. The only time I convert to DNG now is out of necessity (I can't open E-P5 raw files in Lightroom 4).
  9. FastCorner

    FastCorner Mu-43 Veteran

    May 28, 2011
    This is a con for me. Every time Lightroom writes out metadata, it has to touch a multi-megabyte file, potentially corrupting it. With side car files, the original RAW files are untouched and only the XMP file is modified. This also speeds up backup software because the metadata outside of the Lightroom catalog is in very small files.
  10. SojiOkita

    SojiOkita Mu-43 All-Pro

    Feb 23, 2014
    I have the same point of view on DNG...
    It's supposed to be an open format, I see it as an Adobe proprietary format: Adobe only decides how it evolves, and the structure of the file is clearly made for Adobe RAW converters.
    So other software have very few reasons to get into DNG...

    Lightroom works very well with RAW files, and it gives you the ability to use the program of your choice in complement.

    However, there are some real advantages in DNG, that brettmaxwell has already exposed.
    Size is not one of them. If the camera maker know how to make a lossless compression, there will be 0 benefit in converting.

    I add that when you use DNG, Lightroom incorporated the XMP data into the file.
    If you use RAW, you will have a sidecar .xmp file in addition to your raw file.
    You can see it as an advantage or not.
    I perfer having a RAW file + an XMP file, as when I make backups, every version of every photo file is kept. So any change in an XMP file take a few ko, any change in a DNG file would take 15 Mo.

    One thing to keep in mind:
    - you will always be able to convert a RAW to DNG (using Adobe DNG converter)
    - a DNG cannot be converter back to RAW.

    I will maybe use DNG when the conversion will be possible both ways, not before.
    (it's possible when you choose to embed the original RAW into the DNG file, but then the size is multiplied by 2... so, not an option for me)
  11. SojiOkita

    SojiOkita Mu-43 All-Pro

    Feb 23, 2014
    I'm with you with backup software.

    For the risk of corruption, there's supposed to be data verification algorithms in DNG.

    The only real advantage of saving adjustment in the file is that the JPEG embedded in the RAW file is updated with LR settings (instead of keeping the original JPEG from Olympus).
    That what most image viewers will show when you view a RAW file.
    (personnally, I never use image viewers to browse my RAW).
  12. mcasan

    mcasan Mu-43 All-Pro

    Feb 26, 2014
    Personally I want all my eggs in one basket I can watch. I never want separate files for the raw image, and separate files for a jpg preview of XML modifications. If I had a dime for every newbie who has lost or deleted part of that set of files......

    Give me DNG every time. Edited ones sit in my external RAID 1 set for high availability and are backed up (along with all my file system) by a 3 TB Time Capsule. I can also do backups offsite (cloud or other) for critical files.
  13. YantaYo

    YantaYo Mu-43 Regular

    Apr 18, 2012
    I decided to continue with converting RAW files to DNG, after prayers and supplications to the Adobe Gods. Tiffs and jpegs went extremely fast but the RAWs will take some time especially the DNG conversion.
  14. Replytoken

    Replytoken Mu-43 Hall of Famer

    May 7, 2012
    Puget Sound
    Why not archive a copy of the raw files before you convert them to DNG? Storage is quite affordable these days.

  15. YantaYo

    YantaYo Mu-43 Regular

    Apr 18, 2012
    I'll keep my RAW files on an external drive. 5,800 pictures for 2013 and it is taking awhile. I'll have to leave the computer on tonight.
  16. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Enormous DNG files

    I want to revive this thread with my particular question, please. It is about DNG file sizes.

    I bought DXO Optics Pro a week ago to use in conjunction with Lightroom. The basic transfer process is that the RW2 RAW file is opened in DXO, modified, then saved to DNG and exported back to LR. All good so far, it flows quite smoothly.


    The file size of the RW2 is typically about 19.8 MB, but the DNG file that comes back from DXO is about 65 MB!!! What's going on? :confused:  The blurb about DNG is that it is quite efficient in terms of file size.

    I don't want to triple-and-more my RAW file sizes!
  17. OzRay

    OzRay Mu-43 Hall of Famer

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    I thought that the cross process between Lightroom and DxO created TIFF files, which by their very nature are large files.
  18. usayit

    usayit Mu-43 Hall of Famer

    I wouldn't convert to DNG for size benefit alone (I do for other reasons). In some cases, DNG can actually take more space than the original RAW.

    Make sure you have DNG compression option (which is essentially TIFF lossless compression) turned on during your conversion. If working with just TIFF, makes sure the resulting TIFFs are also compressed.
  19. GBarrington

    GBarrington Mu-43 Top Veteran

    I think a more accurate statement would be that he doesn't TELL you everything.
  20. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    DXO can access the RW2 raw file directly, but has no option to export the processed file as, say, raw plus sidecar. The export options are jpeg, tiff, and dng.

    Like I say, no option to keep it as RW2 when exporting from DXO.

    Also no option to compress DNG as far as I can see. Where do I select that option?

    The export from DXO options that I can see (and sample file sizes of a 19.8 MB RW2 file) are:

    JPEG -- varies with Quality option, up to 25 MB with Quality 100

    DNG -- 62 MB, no compression option that I can see

    TIFF -- 96 MB for 16-bit, 48 MB for 8-bit, 33 MB for 8-bit compressed​

    So, if I don't want 8-bit or lossy jpeg files, my only options are a 62 MB DNG or a 96 MB TIFF. :p rotest_emoticon:

    I want a file that is sized more like the RW2 file size of 20 MB, without losses.
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