DNG 1.4 Specification Notes

I’ve received a number of questions about what’s new in the DNG 1.4 specification that we posted earlier this week.  If you’re not comfortable diving into the 101 page document, here’s a quick summary with a few of the potential implications of the new enhancements to the file format.  [Please note that this content is an adaptation of a presentation created by Thomas Knoll, co-creator of Photoshop and creator of Adobe Camera Raw and the DNG file format.]  Before we dig into the new changes I think it’s worth looking at the history of DNG format innovations:

DNG Revision History

DNG Version 1.0 – September 2004

  • Initial Release

DNG Version 1.1 – February 2005

  • Preserving Masked Pixels

DNG Version 1.2 – April 2008

  • Camera Profiles (See also, DNG Profile Editor)

DNG Version 1.3 – June 2009

  • Opcodes (e.g. Lens Corrections)

DNG Version 1.4 – October 2012

  • Default User Crop
  • Transparency
  • Floating Point (HDR)
  • Lossy Compression
  • Proxies

 

Default User Crop

Many cameras have aspect ratio crop modes, e.g. 4:3 or 16:9, yet still save the entire sensor image to the raw file.  In the image below you can see that the raw file contains the entire black area within both of the camera’s crop modes.  The new tags allows the crop setting to be respected but to also allow the customer to “un-crop” the image to see the entire sensor area.  (See the new DNG Recover Edges Plug-in for Lightroom on Adobe Labs to “un-crop” a DNG file: http://labs.adobe.com/technologies/lightroomplugins/)

 

Transparency

When images are “stitched together” in an alignment process or panorama process the resulting image could have “undefined” pixels around the edges.  The new specification update now allows for those undefined areas to exist in a raw file format.

 

Floating Point (HDR)

HDR images have a high dynamic range that will not fit into a 16-bit linear integer encoding.  Floating point storage of information allows for a larger amount of dynamic range to be stored within a file:

  • 16-bit integer data can only store 16 f-stops of image detail.
  • 16-bit floating point data can store over 30 f-stops of image detail.
  • 32-bit floating point data can store hundreds of f-stops of image detail.

Lossy Compression

The current tradeoff in image quality and file size between a DNG and JPEG file:

A lossy compressed DNG file is much smaller but maintains the flexibility of raw data:

DNG Proxies combine the ability to utilize lossy compression with downsampling.

Summary

These new features to the DNG file format are exciting imaging advances that enable numerous workflow opportunities.

14 Responses to DNG 1.4 Specification Notes

  1. xulsolar says:

    When is the implementation going to be available in PS 6 and LR 4?Thanks

  2. RickF says:

    Nice overview! I guess we’ll have to wait to get this integrated with our favorite photo apps!

  3. Hi Tom,
    Will the makernote data finally be stored? And if not, why not? Adobe is a leader in archiving information, yet no Adobe software maintains the critical makernote data when exporting or saving files (please correct me if I am wrong). Even if Adobe chooses not do display the makernote data, why not maintain it for others down the chain?

    I look forward to your response. Keep up the great work :>)

    Michael

  4. Neil Smith says:

    Very cool … just wondering if Adobe has any plans to incorporate the ‘lossy compression’ algorithm into the .cinemaDNG codec? … would be very useful to be able to record compressed RAW in cameras like the Blackmagic cinema camera?

    If Adobe are looking for any beta testers for compressed .cDNG, we’d be happy to volunteer … we’re running a ‘Collaborative Workflow’ Open House on Oct 20th in LA … be glad to have Adobe participate if they interested … details of the event are available on the EventBrite invitation page: http://www.eventbrite.com/event/4529098656

    Cheers,
    Neil
    LumaForge

  5. Fazal Majid says:

    I’m sorry, but lossy compression in DNG is a terrible idea. Now we’ll have to worry about accidentally activating that setting when we convert RAW to DNG and inadvertently losing data in the process. You might as well call it the “silently corrupt my data” setting.

    • Marco says:

      Sorry Fazal, but I cannot understand your point. It is an _option_, you are free not to use it. And since it is not enabled by default…

      Did you call in Canon or Nikon asking them to remove the JPEG mode (you could inadvertently switch from RAW to JPEG and lose data) or the Scene mode on the exposure dial (you could inadvertently switch to it thinking you are still in Manual)?

      Most of the products in this world, either hardware or software, have options, even your toothbrush can have two speeds… It’s up to you to use them well.

    • david k says:

      I totally agree with Fazal.
      RAW was “sanctuarized” format. Meaning that — no options — gives you a warranty you get the greatest information your camera can gives.
      this option breaks this rule…

      • Willi Adelberger says:

        But as it is now todays dng has also a lossy compression option. I think it is the user’s chice to decide if he uses this option or not.

      • Jeff Ellis says:

        David & Fazal – RAW is “sanctuarized” – and if that is your concern, DON’T convert to DNG.
        And there really is no danger of accidentally using Lossy conversion if this is something you don’t want to do. In the Stand Alone DNG converter you have to go into preferences and select it – and that won’t change until you change it.

        As far as accidentally checking the Lossy box in LR – again, LR remembers your last settings, so if you aren’t careless with setting up your prefs the first time you use it – and you’d be a fool not to look at ALL your settings the first time you do this, it won’t change either.

        AND – it saves the files as a separate entity from your RAW files. If you goof, – OOPS, I ACCIDENTALLY MADE MY DNGS LOSSY!!!, and again, you aren’t a fool and don’t actually look at the files & see the smaller file size, the worst that would happen is you do it AGAIN, correctly.

        You telling me you would throw out your original RAW files before checking to see if the DNGs were correct?

  6. seiferflo says:

    Bigger picture size regarding the lossy compression would have been much appreciated. Can’t really see all the subtilities of this new format.
    Else as Fazal mentionned it, this could be quite dangerous if we don’t check it every time.

  7. Jim Batey says:

    Tom, sorry to complain about trivial grammar details, but your use of the pronoun “for” after the verb “allows” is incorrect. Instead of “…allows for those undefined…”, you should say “…allows those undefined…”.

  8. Tom,
    Thanks for the info! I worry about what data is being lost with this “lossy” compression, but I’m very excited about this space-saving archival format. I will definitely try it out in my workflow!

  9. Bill McGrath says:

    Why isn’t the lossy compression option available when importing a NEF to DNG in LR4.2? I can do it after the import, or I can convert using the DNG converter, but I cannot choose lossy compression when doing an import/convert to DNG in Lightroom. Did someone forget to add the checkbox to the options?