March 06, 2007

DNG notes: Compatibility, Color, Hasselblad

A reader named Trace pointed out a discussion happening on the Inside Aperture blog, where there’s been some confusion about the DNG format.  Specifically, there’s been concern that if Adobe were to drop support for conveting from a particular format to DNG, those files would become incompatible with DNG-reading software.  Not to worry:

  • Right now photographers who want to use DNG mostly rely on Adobe software to do the conversion, but that’s not a requirement: the format is publicly documented, and Adobe provides open-source code for implementing DNG reading and writing (via the free DNG SDK).
  • There’s no relationship between the DNG Converter being able to convert a file to DNG, and DNG-reading software’s ability to read DNGs from that camera.  Even if Adobe were to stop supporting conversion from a particular format (something that seems unlikely, but which is possible), DNGs made from that format would remain perfectly readable by DNG-aware apps.
  • It’s true that the DNG Converter does need to be updated for new proprietary raw file formats. That’s the benefit that Adobe is providing: the translation of an unknown to a defined standard. And beyond the conversion experience, ask any photographer using a Leica M8 or Pentax K10D how much they appreciate instant support from the moment their first raw file is captured.
  • I’ve heard from certain camps that DNG is a bit of an empty promise, that these companies really have to do custom work for each camera & that they therefore can’t support DNGs made from cams they don’t support.  If that’s the case, why are DNGs compatible with Camera Raw in Photoshop CS1, which was last updated some two years ago?  It may be that a developer will want to do custom work for a camera, even if images from that camera are in DNG format, but doing so isn’t a requirement. [Update: See the comments on this story for more info on these points.]

At the end of the day, your photos are your photos, and you shouldn’t be beholden to Adobe or to any other company to read them.  Ultimately Adobe would like to turn stewardship of the format over to a standards body, but we’ve wanted to let it build momentum first.

While I’ve got your ear on the subject of DNG, here’s a bit more that may be of interest:

  • Lightroom and Camera Raw support the
    Hasselblad H2D, but the H3D raw file is 3FR, not DNG.  Why is that, and what does it mean?  In short, before handing off data to raw conversion/workflow software, Hasselblad wants to do additional custom  processing that isn’t practical to do in-camera.  According to the Hasselblad site,


    "3FR files can be converted into Adobe’s raw image format DNG (‘Digital NeGative’), bringing this new technology standard to the professional photographer for the first time. In order to optimize the colors of the DNG file format, conversion from the 3FR must take place through FlexColor. The DNG file format enables raw, compressed image files to be opened directly in Adobe Photoshop. Hasselblad image files carry a full set of metadata, including capture conditions, keywords and copyright, facilitating workflow with image asset management solutions."

  • Carl Weese wrote a piece called "There’s DNG—And Then There’s DNG," in which he mentions that his white balance settings changed after he updated to Camera Raw 3.7.  Thomas Knoll notes that to get the previous appearance, it’s possible to choose that option in the Camera Calibration popup menu.  (I don’t have any of these files on hand, so I haven’t tried this myself.)
Posted by John Nack at 11:24 AM on March 06, 2007
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