4 Replies Latest reply on Apr 10, 2008 11:16 PM by Hopsternew

    ACR 4.3.1 and Leica M8 DNG files

      Hi, I am applying develop settings to these files with ACR. Once I have made those adjustments CS3 Bridge reports the files as about 5MB instead of the original 10MB. This is the original DNG, not a picture saved as a PSD or other from the DNG. When I reset the develop settings the file size remains smaller. I understood that Raw files are not changed by this editing, provided I do not convert them to another format.
      Clearly there is something happening I don't understand properly. Can anyone shed any light on this?
        • 1. Re: ACR 4.3.1 and Leica M8 DNG files
          Ramón G Castañeda Level 4
          You might indicate the exact version of your OS, just to see which one of us can help. I'm a Mac user.
          • 2. Re: ACR 4.3.1 and Leica M8 DNG files
            Greg Barnett Level 2
            Im guessing that this is due to the more efficient Adobe lossless compression that is applied to your Leica DNGs once youve made an adjustment and applied it to the file. And if Im correct, then removing the adjustment would not restore the original file size since the compression had already been applied.
            • 3. Re: ACR 4.3.1 and Leica M8 DNG files
              Thomas Knoll Level 2
              You have your preferences set to update the embedded DNG previews (which is not the default value for that settings by the way, so you must have changed it).

              This requires the DNG file to be rewritten, and we always use lossless compression when doing so (because there is not good reason not to use lossless compression). No image data has been lost, it has just been losslessly compressed.
              • 4. Re: ACR 4.3.1 and Leica M8 DNG files
                Hopsternew Level 1
                Thank you, Ramón. My apologies for not including XP SP2 as my OS.
                Thank you Greg and Thomas. Evidently I have changed the default setting for the embedded previews update when following a tutorial from the lynda.com site.
                The extra lossless compression is excellent news also as I am quickly building a large number of files as I learn the camera and software.
                I am very surprised as I thought that the original Raw files were not ever altered at all, except for the edit information being stored with them. However I understand your explanation. This particular camera stores its files which start as 16 bit, effectively 14 bit, in an unusual way so that they are temporarily compressed to be 8 bit then re-expanded with very little loss of data.
                The important information for me of course, is that there is no loss of data by the efficient lossless compression in ACR.

                Thanks again.