3 Replies Latest reply on Aug 31, 2010 9:33 AM by dfranzen_adobe

    Tech questions for an Adobe DNG engineer

    chuckfrance

      Hi,

       

      I'm a staff photographer at a university here in the U.S. and have our photo staff is having a spirited discussion concerning the good and bad of DNG.

       

      First off I have been using DNG for a few years now as part of my workflow. In my freelance business and now at my "day job". BTW...I choose not to embed the orginal RAW file...I just the DNG as my RAW.

       

      Previously before I got here at my job we were a Nikon only shop and the workflow consisted of RAW editing in Nikon CaputreNX, Photoshop and Photo Mechanic (for metadata tagging).

       

      I say that there is no discerable difference in an original NEF and a converted DNG. Others agrue that there is a "quality" difference in using a DNG opposed to the NEF.

       

      I understand all the benefits of using DNG....stanards, best practices....many professional organizations using DNG...some camera mfgs using DNG etc. but can someone at Adobe technically explain to me (I'm an ex software test engineer and all around tech guy for 10 years) how the conversion process works and what if ANY changes in the original file occur.

       

      Many thanks in advance.

       

      Regards,

       

      Chuck

        • 1. Re: Tech questions for an Adobe DNG engineer
          JimHess-DIrcbP Level 3

          I don't know if this is going to give you everything you want.  But here is the published DNG specification:


          http://www.adobe.com/products/dng/pdfs/dng_spec.pdf

           

          Sorry, the link doesn't work.  But that is where you can find it.

          • 2. Re: Tech questions for an Adobe DNG engineer
            JimHess-DIrcbP Level 3

            Let's try a different link.  If you scroll down this page, you will find references to several PDF files that might provide you with some of the information you are looking for.

             

            http://www.adobe.com/products/dng/

            • 3. Re: Tech questions for an Adobe DNG engineer
              dfranzen_adobe Level 3

              Hi Chuck,

               

              I can try to answer some of your basic questions.

               

              I say that there is no discerable difference in an original NEF and a converted DNG. Others agrue that there is a "quality" difference in using a DNG opposed to the NEF.

               

              When using Adobe Camera Raw--whether in the plugin for Photoshop, Bridge, etc. or in Lightroom--you should see no difference between the result you get for a NEF and a non-linearized DNG created from that NEF. When processed using the same develop settings, they should be identical. If you see a difference, we'd consider that a bug--please report it to us by posting sample files (NEF, DNG and the settings used).

               

              I don't know if other raw converters will produce identical results for a NEF and DNG.

               

              If the linearize (demosaiced) option was chosen when converting the NEF to DNG, the process of "developing" the DNG and NEF inside Camera Raw is slightly different. The NEF will be demosaiced on the fly, whereas the starting point for the linearized DNG is the demosaiced data that was created during conversion to DNG. I would not expect this to degrade the "quality" of the image, but if anyone has an example where it does create a qualitiative difference, I'd really like to have an example to investigate as a potential bug.

               

              When you convert NEFs to DNG using the default options you should be getting non-linearized DNGs, not demosaiced DNGs.

               

              ...can someone at Adobe technically explain to me ...what if ANY changes in the original file occur.

               

              Converting a NEF to DNG does not change the original NEF file at all.

               

              -David Franzen