11 Replies Latest reply on Jul 3, 2007 5:54 AM by don solomon

    DNG options in Bridge/ACR CS3.

    drjchamberlain
      Dear members:

      This is a crosspost since it affects DNG, Bridge and Camera RAW so please forgive me for placing the same post to more than one discussion forum.

      I recently digitized a large number of slides with a Nikon scanner and saved the images as TIFF files (only options were TIFF or NEF. NEF created by Nikon scanners is not supported by ACR so the logical choice was TIFF).

      Since my workflow requires the addition of metadata to these images I decided that DNG would be the ideal file format as the metadata can be incorporated in the image without the need for a second XMP sidecar file that can be easily lost or misplaced.

      The tools I have found that can convert TIFF images to DNG are Adobe's Lightroom and ACR hosted by Bridge CS3. Lightroom offers a simpler and more straightforward conversion with not options offered. ACR hosted by Bridge CS3 offers some options - compression and linear image. These options are covered under the help files when the conversion to DNG is made from a RAW file. However, the help files don't provide enough details about the conversion from TIFF (and JPEG also) to DNG.

      The questions I have are:

      1. When converting TIFF to DNG is it possible to keep the image intact so that it can be later extracted much in the same fashion that a RAW file can be preserved should it become necessary to recover it later ? In this case, what application could be used in the future to extract the original TIFF image from the DNG file ?

      2. The option to compress the original image as ACR hosted by Bridge CS3 makes the conversion can save some disk space but will it affect how other applications open these DNG files ? Will other applications continue to open these files and what impact will it have on performace (time necessary to decompress and open image) ?

      3. What does the linear option do the TIFF or JPEG file as the image is being converted to DNG ?

      4. This is not necessarily an Adobe question but I noticed that Apple's support for DNG is erratic and unreliable. I have opened some DNG files with Preview but the ones I have created with both Lightroom and ACR hosted by Bridge CS3 are not recognized by it. Why is there a distinction in the way Apple's Preview treats these DNG files ? Is there a difference between DNGs created from RAW files and DNG files created from TIFF or JPEG images ?

      Thank you in advance for your help,

      Joseph Chamberlain
        • 1. Re: DNG options in Bridge/ACR CS3.
          don solomon Level 1
          I can answer question 1 and 2 for you.

          No, the only pure recovery I know of is if you embed a RAW into a DNG file. for the rest you would have to load the DNG and then save a Tiff or JPEG. Since a DNG is really a tiff container to start with, I suspect that the'losses', if indeed there are such, would be minimal when going back from dng to tif. However, the best advice I know of is to archive your originals--RAW or Tiff, as you always have them if you need them.

          As for 2. Why take any chances for a meager saving of space. Disk storage is so cheap now as to make that virtually unnecessary.

          Dng is by no means universal. One has to be reasonably sure that they are not going to encounter software that shuns it or treats it idiosyncratically, if they use it.

          I personally think its only virtue is that it allows metadata embedding for virtually all RAW formats (sooner or later) and provides easier access to Adobe (mainly, but not exclusively) and some other applications that users of non mainstream digital cameras would otherwise have difficulty accessing.

          By the way, as a Nikon shooter, I do not use DNG--storage is simply too inexpensive to bother for the space saving and I auto save all Nefs and sidecars to offline storage as I work--but I do convert for customers who want to use it. I have yet to have a request for the linear option and I am not a MAC user, so others will possibly help you out there.

          I do a lot of scanning professionally, so the question I have for you is why save tiffs to dng since you can write metadata directly to them anyway and the space savings is relatively small?
          • 2. Re: DNG options in Bridge/ACR CS3.
            drjchamberlain Level 1
            Don:

            Thank you for your response and suggestions.

            > I can answer question 1 and 2 for you.

            > No, the only pure recovery I know of is if you embed a RAW into a DNG file. for the rest you
            > would have to load the DNG and then save a Tiff or JPEG. Since a DNG is really a tiff
            > container to start with, I suspect that the'losses', if indeed there are such, would be
            > minimal when going back from dng to tif. However, the best advice I know of is to archive
            > your originals--RAW or Tiff, as you always have them if you need them.

            I will try the technique you describe here and save a tiff from a DNG so see if the TIFF can be extracted from the DNG wrapper this way. As far you keeping copies of my originals I always do that and the TIFF files are archived before they are converted to DNG.

            > As for 2. Why take any chances for a meager saving of space. Disk storage is so cheap
            > now as to make that virtually unnecessary.

            Good point. Keep in mind that a typical scan of a slide using the highest resolution on dedicated film/slide scanners such as the Nikon model I own has a resolution of 4000 dpi and generates a TIFF file with approximately 120-130 MB. But I would certainly prefer to give up storage space than to compress the image and take the chance that something might happen to it.

            > Dng is by no means universal. One has to be reasonably sure that they are not going to
            > encounter software that shuns it or treats it idiosyncratically, if they use it.

            I am experiencing this now with Apple's Preview can comes bundled with OS X. It offers erratic support to DNG - it opens some DNG files but not others.

            > I personally think its only virtue is that it allows metadata embedding for virtually all
            > RAW formats (sooner or later) and provides easier access to Adobe (mainly, but not
            > exclusively) and some other applications that users of non mainstream digital cameras
            > would otherwise have difficulty accessing.

            > By the way, as a Nikon shooter, I do not use DNG--storage is simply too inexpensive to
            > bother for the space saving and I auto save all Nefs and sidecars to offline storage as I
            > work--but I do convert for customers who want to use it. I have yet to have a request
            > for the linear option and I am not a MAC user, so others will possibly help you out there.

            This is the very reason I want to convert my TIFF files to DNG. I wish to avoid the sidecar files as I have found them to be an annoyance in my workflow as they can get lost, misplaced and in some instances even deleted by mistake.

            > I do a lot of scanning professionally, so the question I have for you is why save tiffs to
            > dng since you can write metadata directly to them anyway and the space savings is
            > relatively small?

            This is an interesting point but I can't seem to locate detailed technical information on how Bridge treats TIFF files as it adds metadata and also as it converts them to DNG. Will the metadata (keywords, labels, ratings and others) be incorporated as part of the TIFF file ? Will this added metadata affect other viewers (the metadata added by Bridge may render the image not readable by other software) ? What if I wish to remove some of this metadata later as I may not wish to allow someone I am sharing the image with to see it - will Bridge remove the metadata from the TIFF file or it simply remains there ?

            These are some of the questions I have but haven't yet found a good source of informaion or tutorial that covers these aspects. Do you have any suggestions ?

            Thank you again for your help and suggestions.

            Joseph Chamberlain
            • 3. Re: DNG options in Bridge/ACR CS3.
              don solomon Level 1
              I have converted tiffs to DNG for customers, but as I said before the space savings is in most cases minimal. However, I have never gotten a report back that there was any problem with their dngs. In my own tests, I cannot detect a discernible difference.

              Bridge will write metadata, keywords, and camera raw settings, etc,etc,to tiffs. I have never had any problems in that regard with respect to Adobe products reading the metadata. There was an imcompatibility problem with Bridge 2.0 and some web hosting sites. As far as I know that has been fixed.

              If you are scanning to tiff, there is one important point to remember if you open the scans in PS--as I do, since the first operation on any scan is the selective color dialogue, then shadows and highlights, then I save the file and reopen as Camera RAW using Open AS. I make adjustments and hit Done.

              Fine so far. If, however, you see some little correction that you want ot make in PS and go back there, that last correction will not be saved as metadata. The last step for each image must be an ACR 'Done" if you want the image to reflect all your PS and ACR changes. Sometimes, it is easy to overlook that in the heat of editing.

              Other than that, I know of no problems with metadata, etc, using Bridge/ACR.
              • 4. Re: DNG options in Bridge/ACR CS3.
                JimHess-8IPblY Level 3
                I have to ask this question for my own information. I'm not challenging your workflow at all. I want to understand the merits of saving a tiff image as a DNG image. A tiff image is not raw data. It has already been processed by the camera (or whatever capture device was used). My understanding is that the purpose for using DNG is to preserve the raw data in a more standard file format. I'm not questioning the editing of the tiff image in Camera Raw cause I routinely do that myself. But what is the advantage of converting the image to the DNG format?
                • 5. Re: DNG options in Bridge/ACR CS3.
                  don solomon Level 1
                  A small space saving is the only one I can think of. Metadata gets written to Tiffs, so no advantage there. Not worth it to me, for sure.
                  • 6. Re: DNG options in Bridge/ACR CS3.
                    drjchamberlain Level 1
                    HI, Don:

                    > I have converted tiffs to DNG for customers, but as I said before
                    > the space savings is in most cases minimal. However, I have
                    > never gotten a report back that there was any problem with their
                    > dngs. In my own tests, I cannot detect a discernible difference.

                    Did you convert these DNGs from RAW images ? Perhaps there is a difference in the way DNGs are created depending on whether the original image is RAW or TIFF/JPEG. I have run into issues with a few TIFF images I have converted to DNG using both Adobe Lightroom and Bridge CS3. Apple's Preview has inconsistent support to DNG. All TIFF files I have converted to DNG can't be opened with Preview. I have written to Apple to get feedback on this issue but haven't received anything yet.

                    > Bridge will write metadata, keywords, and camera raw
                    > settings, etc,etc,to tiffs. I have never had any problems in that
                    > regard with respect to Adobe products reading the metadata.
                    > There was an imcompatibility problem with Bridge 2.0 and
                    > some web hosting sites. As far as I know that has been fixed.

                    I tried to add metadata to some TIFF images and found that the metadata (in this case keywords) was added to the image files in the background although the file was never re-saved by me. I used Bridge CS2 as Bridge CS3 is simply non-functional due to the numerous bugs it has.

                    > If you are scanning to tiff, there is one important point to
                    > remember if you open the scans in PS--as I do, since the first
                    > operation on any scan is the selective color dialogue, then
                    > shadows and highlights, then I save the file and reopen as
                    > Camera RAW using Open AS. I make adjustments and hit
                    > Done.
                    >
                    > Fine so far. If, however, you see some little correction that you
                    > want ot make in PS and go back there, that last correction will
                    > not be saved as metadata. The last step for each image must
                    > be an ACR 'Done" if you want the image to reflect all your PS
                    > and ACR changes. Sometimes, it is easy to overlook that in the
                    > heat of editing.

                    I am not sure I follow. It seems clear to me now that all the metadata (keywords as well as ratings, labels and others) do get written to the TIFF files. But you say here that TIFF files will record edits done to the images much the same way that DNGs or sidecar files record edits. Did I understand this right ? According to the paragraph above the only edits that get written to the TIFF file are those done in ACR. In case I want to save the edits done in Photoshop to the images I need to open them in ACR after the Photoshop edits have been done and then hit the Done button. Is this correct ?

                    Thank you again for your help,

                    Joseph Chamberlain
                    • 7. Re: DNG options in Bridge/ACR CS3.
                      drjchamberlain Level 1
                      Hi, Jim:

                      > I have to ask this question for my own information. I'm not
                      > challenging your workflow at all. I want to understand the merits
                      > of saving a tiff image as a DNG image. A tiff image is not raw
                      > data. It has already been processed by the camera (or whatever
                      > capture device was used). My understanding is that the purpose
                      > for using DNG is to preserve the raw data in a more standard file
                      > format. I'm not questioning the editing of the tiff image in
                      > Camera Raw cause I routinely do that myself. But what is the
                      > advantage of converting the image to the DNG format?

                      My main reason to convert TIFF images to DNG is to use the DNG file as an envelope or wrapper that keeps the image and all the metadata in it. In other words, my goal is to avoid using the sidecar files that simply don't work in my particular workflow. Another benefit of DNGs is the ability to save information about edits that have done to the image (in ACR and maybe in Photoshop as well) but this is secondary and not critical to my workflow.

                      In case I can use Bridge to write (and remove or erase) metadata to my TIFF files in a predictable, consistent and reliable way the conversion to DNG is not longer necessary. I can convert my RAW files to DNG for the reasons discussed above but keep my TIFF files from scanned slide/negatives just as they are - TIFF files.

                      Thank you for the input and suggestions.

                      Joseph Chamberlain
                      • 8. Re: DNG options in Bridge/ACR CS3.
                        01af Level 1
                        Joseph Chamberlain wrote:
                        > In case I can use Bridge to write (and remove or erase) metadata
                        > to my TIFF files in a predictable, consistent and reliable way
                        > the conversion to DNG is not longer necessary.

                        This conversion never was necessary. Adding metadata to TIFF files is just the same as adding metadata to DNG files ... actually it's even more reliable (DNG files won't accept some of the metadata fields due to a bug). TIFF files with metadata are still TIFF files.

                        -- Olaf
                        • 9. Re: DNG options in Bridge/ACR CS3.
                          don solomon Level 1
                          Joseph,

                          My point was that only files that originate from Bridge or ACR opened in PS will have the metadata written to them. When you open directly from a scanner (as I do)with PS and produce a Tiff and then save it, it does not automatically write the changes to metadata that will give you 'nondestructive' editing. I always finish my editing of an image from ACR. Changes done in PS are pixel changes. Changes done in ACR are metadata changes only, unless save the image out to a format like Tiff or Jpeg.
                          • 10. Re: DNG options in Bridge/ACR CS3.
                            drjchamberlain Level 1
                            Hi, Don.

                            Now I understand what you meant. Since I switched to Bridge it has been the one application at the heart of my workflow. I always browse my images with Bridge and then open then in ACR (if RAW) and follow with Photoshop.

                            Since the upgrade to CS3 I haven't followed the same protocol as Bridge CS3 has been by far one of the worst upgrades I have ever experienced in terms of bugs and conflicts.

                            But I do get your point about using either ACR or Bridge as the starting point for changes that are written to metadata and for non-destructive editing.

                            Some of my images are TIFF and I haven't worked with them yet but I assume that by opening them from within ACR the same will happen. Besides the metadata added by the user in the form of keywords, labels, ratings and others, I expect that the same level of non-destructive editing applied to RAW images will also work for TIFFs. I have to work with this to confirm whether it does happen or not.

                            Thank you again for your help and feedback.

                            Joseph Chamberlain
                            • 11. Re: DNG options in Bridge/ACR CS3.
                              don solomon Level 1
                              Hi, yes that will be the case if you have preferences checked to open Tiffs and Jpegs in ACR. The metadata from Bridge and ACR will be written to Tiffs and Jpegs as well--directly to the file itself. It writes sidecar files only for RAW images. All the rest get the XMP data written directly to the file.

                              If you finish an image in ACR as the last step in your workflow, any previous work will be written to the file--even the destructive changes made in PS will get locked in along with any last minute changes to the Tiffs--I always open first in PS and do Selective Color adjustments to remove any stubborn color casts from my scanners that are more difficult to remove in ACR, and then I finish my adjustments in ACR. Everyone's workflow will differ silghtly, of course.