lreisner Loc: Union,NJ

The changes are stored in the Lightroom Catalog, not in the original file. The original files are never changed which is why why LR is non destructive. For backup of you edits, allow LR to create XMP files. That way if anything ever happens to the Catalog, gets corrupted or lost, you can restore the edits in a rescue Catalog.

The dng files may contain metta data but that is not the same as edit information. Tiff and psd files do retain editing information created in Photoshop. They can be really large files as a result.

CHG_CANON Loc: the Windy City

The DNG does contain the LR edits, just the current state, not the history, similar to the XMP. Only the LR catalog has the full history of the image as well as any cataloging info like assigned collections. Keywords are stored in the files, both the DNG and XMP. A 16-bit TIFF can contain the PS edit layers just as an actual PSD, but it depends on the photographer's decisions about how to store their TIFFs.

Depending on your DNG setting, the DNG may even 'contain' the original image file, more than just the image-data payload portion that is stored in the DNG as default. The DNG is / can be much more than described above.

lreisner Loc: Union,NJ

Thanks for the correction and additional information.

DirtFarmer Loc: Escaped from the NYC area, back to MA

Since one of the supposed advantages of dng is that it contains the edits, I did the experiment, which shows that the edits are only contained in the dng from the primary edited file in LR. Virtual copies are ignored as far as the dng file is concerned.

CHG_CANON Loc: the Windy City

For a 'virtual copy' this seems to make since. Does it at least create a XMP for the virtual copy?