Here’s some follow-up clarifications that will hopefully address some of the questions brought up concerning XMP files and how Lightroom saves RAW images.
- Lightroom automatically creates an XMP (also known as sidecar data files) file whenever a change is made to the RAW file within LR only if the “automatically write changes into XMP” selection is made in the catalog settings preferences in LR. The settings on your individual computer will determine whether you will see these sidecar files or whether they’ll remain hidden from view on your system. On my Mac, they are hidden. Regardless of whether they are seen or not, they’ll travel with the original image file after they have been created.
- The highlighted image “state” in the history panel at the left of the develop interface in LR determines what version of your image will be saved to XMP.
- If you jump out of LR to edit your RAW file in Photoshop, the changes will be saved in the XMP data and a copy of the image will be saved back to LR as a flattened .PSD document if you save when exiting Photoshop.
- Changes made in Lightroom are committed to these XMP files immediately. If you quit Lightroom, the changes will be there when you open the program again (they’ll be there if you open the file in Photoshop or Elements too). If you want to go back to the original file you can either select the original imported file from the history panel within LR OR delete the file’s XMP sidecar from your computer. Either way will work. The LR way is easier and quicker though.