4 Replies Latest reply on Mar 5, 2009 8:00 AM by Ramón G Castañeda

    Dng - 72 ppi when converted

      Hi, I'm converting raw files from Canon 5DII, they are 180 pixels per inch and when converted to dng they come out at 72 pixels per inch. The histogram of the two images are also slightly different and so are the colours. Can anyone explain?
        • 1. Re: Dng - 72 ppi when converted
          Ramón G Castañeda Level 4
          The resolution in ppi is irrelevant. What counts is the dimensions in pixels, so many pixels wide by so many pixels high. You can change the resolution in ppi at will, as long as you do NOT resample the image, and the pixels will remain untouched.

          The colors and histogram issue is a different story of course. Without knowing what you have done to the files and how you are comparing them, it's hard to tell.
          • 2. Re: Dng - 72 ppi when converted
            Level 1
            Thanks for that info about the ppi - that's one thing less to worry about. About the colour change when converted from CR2 to Dng with the Adobe DNG converter- I suspect that the problem is with the iView Mediapro which I'm using to view - I don't think the raw files are colour managed and that's why the two files look different. As for the histogram - I'm not sure why that changes with the conversion. Thanks anyway for your reply - I'm pleased I don't have to worry about those ppi's.
            • 3. Re: Dng - 72 ppi when converted
              bokeron2008 Level 1
              ppi may be irrelevant, but it is USEFUL. I asked for this some time ago, and got the same response "ppi is irrelevant - etc" from ... someone else :).

              I still don't understand what's the problem with including an editable ppi value inside dng metadata.
              I use it for calculating print sizes of my edited files, based on my printers settings. It makes my life easier. I can obviously live without it, but why do I have to, when even the NEF files i use give me that irrelevant-but-useful bit of info ? I could also live without any metadata altogether, but ...

              My request : Just treat ppi as user-metadata if you wish, editable, irrelevant, but "there"...
              • 4. Re: Dng - 72 ppi when converted
                Ramón G Castañeda Level 4
                PPI doesn't become relevant until you go to print. You have to convert your DNG file before printing it anyway, and the resolution in ppi is set by you in the raw converter of your choice.