When you clean a DNG file, DNG cleaner takes the following steps:

  1. Removes any XMP information, including Lightroom/ACR settings.
  2. Removes any Lightroom/ACR profile information. (AKA non-embedded profiles).
  3. Optionally removes any opcodes.
  4. Deletes any existing preview images, and regenerates a “standard” set.
  5. Optionally compresses the image data.