10 Replies Latest reply on Oct 14, 2008 10:14 AM by SverreE

    DNG as a format for scanned images

      I want to archive all of my family's old photos and negatives in a lossless format. Do any of the programs in the photoshop family allow me to save the scanned images as a DNG file? Is this the best way to go? Should I use TIFF instead? I plan on saving a JPEG version for printing future copies, but also want a long-term storage option. Any suggestions? Thanks for the help.
        • 1. Re: DNG as a format for scanned images
          MadManChan2000 Adobe Employee
          For scans it's probably better to use TIFF.
          • 2. Re: DNG as a format for scanned images
            Hi Peter

            Even though I haven't used it myself, my friend who is a trained image archivist, told me that a lot of the major image library's are now using JPEG 2000 as their main archival format.
            It might be worth looking at?
            • 3. Re: DNG as a format for scanned images
              Level 1
              You can save the scanned TIFF's to DNG from Adobe Camera RAW (and I think Lightroom too). You can't save TIFF's to DNG from the stand-a-lone DNG converter though.

              People will say that the best thing to do is keep them as TIFF's, however I choose not to. Basically, all my original files are converted to DNG, whether they are RAW's from my DSLR, JPEG's from my compact camera, or TIFF's from my scanned negatives. The reason I do this is as follows:

              Firstly, with the JPEG's and TIFF's, by converting them to DNG format means that I can't accidently overwrite the original during post processing (for example, imagine resizing an image for the web and accidently overwriting the original would be a nightmare).

              Secondly, it means that I can easily identify each file by type. DNG's are always the original and TIFF's are always the full size edited file, with layers, etc. These are the only two you really need to keep, but I also keep smaller JPEG versions too, which I have converted for web/email/fast browsing use.

              Thirdly, by converting RAW's and TIFF's to DNG, it lowers the file size of my originals. With JPEG's it increases the file size, but is not too much of a problem as this is way off-set by the savings of my scanned negatives (my negative scans are approx. 115MB each, but as DNG's they are approx 84MB).

              TIFF is the number one archival format, but if your edited 'working' file is saved as a TIFF anyway, there is no need for the original to be too because it would just be more confusing, take up more space and create the potential to accidently over-write the original.

              Also, if you open the images from Adobe Camera Raw into Photoshop as Smart Objects, you willl still have a version of the original in the TIFF file anyway, as it uses non destructive editing. So in 50 years time, you will have not only DNG versions, but also TIFF versions that can also be used as originals if need be.
              • 4. Re: DNG as a format for scanned images
                Ramón G Castañeda Level 4
                Whatever floats your boat. Every user has his/her own workflow. So far, I don't deal with DNGs nor with JPEGs.

                I keep visiting this forum from time to time, just to make sure I'm not missing anything.
                • 5. Re: DNG as a format for scanned images
                  Level 1
                  TIFF offers loseless compression like DNG. Are you saying you save space with DNG compared to compressed TIFF's?
                  • 6. Re: DNG as a format for scanned images
                    Level 1

                    VueScan offer the options of saving scans in both TIFF and DNG.
                    • 7. Re: DNG as a format for scanned images
                      Level 1
                      Hello Sverre

                      Yes. It was a while ago since I done the tests, but here's an example:

                      Original TIFF scan = 116.34MB
                      Converted to DNG = 79.24MB

                      When saved as:
                      TIFF, No Image Compression = 116.34MB
                      TIFF, LZW Image Compression = 133.35MB
                      TIFF, ZIP Image Compression = 106.31MB
                      • 8. Re: DNG as a format for scanned images
                        Level 1
                        I get no difference when I convert a D300 RAW file to TIFF and then to DNG in LR:

                        TIFF, LZW = 7157kB
                        DNG, loseless, medium preview = 7287kb
                        DNG, loseless, none preview = 7233kb

                        • 9. Re: DNG as a format for scanned images
                          Level 1
                          We are talking about different things. I was talking about scanned negatives as per the OP.

                          As far as converting RAW files to DNG, I have not tried Nikon RAW files, only Canon RAW files. A 7.2MB CR2 will be about 1 MB smaller when converted to DNG. I would imagine the amount the file size changes during conversion may vary depending on the proprietary RAW file.
                          • 10. Re: DNG as a format for scanned images
                            Level 1
                            I first made a TIFF file and then converted
                            b the TIFF file
                            to a DNG file.

                            But compression rate could of course be different depending on the source of the TIFF file. May be the DNG algorithm is better when the source is a scanner.