Do you know if you’re Lightroom Catalog is writing XMP data automatically? An XMP file is a sidecar or additional file that contains the metadata to a raw image. When Lightroom makes changes to a raw file, the raw file itself remains unchanged. A sidecar file is created to tell editing programs what has changed in the image.

“Adobe’s Extensible Metadata Platform (XMP) is a file labeling technology that lets you embed metadata into files themselves during the content creation process.” – Adobe

By default, Lightroom does not automatically generate XMP files.

What is stored in XMP files

  • Filenames
  • Metadata
  • Keywords
  • Copyright
  • Edits
  • File Changes, etc…

Why You Don’t Need Them

Lightroom at it’s core is a database, thus it stores all of this info in your catalog file. If you’re only using Lightroom, then you really don’t need to create all the extra files.

Why You Should Have Them

Your edits and metadata saved in Lightroom don’t actually affect the raw file. It remains untouched because Lightroom is non-destructive editing software. If for some reason the catalog becomes corrupt (and you don’t have a backup of your catalog file), quite simply you’ll lose all of your edits. Only when you export an image does Lightroom “bake” all of the edits and changes into a final image.

Also, if you’re using other applications where you rate or edit photos, like Photo Mechanic or Adobe Bridge, then writing to XMP lets programs exchange information.

How to Automatically Generate XMP Files

From the Catalog Settings window (access via Lightroom menu on Mac, Edit menu on Windows), choose the Metadata tab. Make sure there is a check mark next to “Automatically write changes into XMP”. By default, this is unchecked. And that’s it…just one setting.

This change isn’t retroactive, so if you want to write XMP files for your entire library, choose the All Photos folder and hit Command-A or Control-A to select all the photos and then choose Metadata > Save Metadata to Files.

When you’re working with Adobe Camera Raw, Photoshop will automatically create the XMP file for each image. I’m not really sure why Lightroom doesn’t do this automatically, but I think it’s good practice to make sure Lightroom writes all changes to XMP. You can never be to careful.