What is an XMP file,please?

Discussion in 'Digital Darkroom' started by avril, May 14, 2006.

  1. When I process a NEF file in Photoshop CS2 it creates an additional
    file called an XMP file. What is it and do I need it? The file
    association doesnt recognise the file -so guidance would be much
    appreciated.Thanks in advance ladies and gents.
  2. It's a file for metadata, similar to IPTC. When you add file info in Photoshop (File>File info), such as title, captions, keywords, etc., this is metadata which goes into the XMP file. This is probaby a pretty simplistic description. Others will know more. ;)
  3. Here's a link to what any file extension means. - http://filext.com/
  4. "Adobe's Extensible Metadata Platform (XMP) is a labeling technology that allows you to embed data about a file, known as metadata, into the file itself. With XMP, desktop applications and back-end publishing systems gain a common method for capturing, sharing, and leveraging this valuable metadata ラ opening the door for more efficient job processing, workflow automation, and rights management, among many other possibilities. With XMP, Adobe has taken the モheavy liftingヤ out of metadata integration, offering content creators an easy way to embed meaningful information about their projects and providing industry partners with standards-based building blocks to develop optimized workflow solutions.
    For a complete rundown check out Adobe's website, I found this in less then 30 seconds.
  5. The XMP file contains any modifications you make to NEF files using ACR - the NEF files themselves are not changed. If you back up the directory, save the XMP files too, as well as the Bridge cache files.
  6. In Adobe Bridge, if I highlight an image, then open the conversion dialogue, via <ctrl> "r", then click on the little > button to the right of "settings", then preferences (or <ctrl> "k"): I see choices:

    Camera Raw Database or Sidecar .xmp files

    I think choosing the first will stop generation of these files.

    For the ones that already exist, (assuming windows system), I'd sort the directory with those files "by type", and delete the lot. Just to be on safe side, don't summarily delete, just send to recycle bin.

    Personally, I don't like a program that generates massive new files, find it an irritant.
  7. Just a minor addition to Peter's post. Do your file sorting from within Bridge and your .xmp
    files will be moved automatically with your image files. You can also filter them out in Bridge
    if the icons annoy you.
  8. the only reason for writing to a central database is that you don't generate the extra .XMP files.
    This is incorrect. One can gain a lot from the usage of a centralized cache.
    You can ensure that your images and the central cache are always on separate physical hard drives. This removes a major performance bottleneck as one disk can now read while the other writes. This can create an order of magnitude of performance improvement in worst case scenarios.
  9. As someone who deals a lot with various XML files, XMP are simply "XML for Photos", hence its name. It's really that simple. XMP's simple encode the data transformations made in processing your Raw file to the photo editing tool's workspace.

    Think of it too like this:

    XML is to data description as to how HTML is to layout description.
  10. When opening RAW files with Photoshop CS4 changes you make are not saved to the RAW file which I think is good. It does however make a note of the changes you have made and when you re-open the RAW file it auto displays the changes you have made. From the xmp file.
    You can open it in Notepad but hard to read. However if you open in Excel you get one item per line and easy to read. For example <crs:Contrast>+25</crs:Contrast> means I had increased contrast by 25.
    In contrast when opening a Jpeg file with Photoshop it strips out some of the information. Using the Pentax Photo browser I can see with unaltered Jpeg files lens type as well as setting with aperture, speed and sensitivity but once loaded into Photoshop although some info remains Capture mode, Autofocus, Flash etc are removed. And Firmware/Software is changed to Adobe Photoshop CS4 Macintosh it also can no longer be displayed with the camera.
    I would say the idea of leaving the file as it is and adding an extra file 8k file rather than a second 12.4Mb file saves a lot of space on storage media and must be good.
    However when opening the same file with Pentax Photo Laboratory all the info stored by Photoshop is ignored so I have to start again from scratch. And I can't save the changes to the RAW file it has to be as Jpeg or TIFF so yes I do like the CS4 ability however I have Version 7 at home and can't really justify the expense to upgrade my home edition.
    I will admit at first I did wonder what the xmp files were but lucky I am at college so could ask lecturer.
  11. Thank you Mendel Leisk Your post was easy to understand and it fixed the issue.

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