Fortunately this is not required simply because Raw processing software applications do not ever make physical changes to the raw files. The raw files are not viewable image files and the data they contain is utilised to process and create a viewable file i.e. tiff or jpeg which then is saved as a separate image file.
For this process you need specific applications which are designed to process the raw data, like Adobe Camera Raw in Photoshop and Lightroom , SilkyPix, Capture One, DxO Optics, DCRaw, ON 1 Raw, software provided by the Camera Manufacturer, and a few dozen more. Each one having their own special "recipe".
The Firmware in your Camera also has the ability to process the raw data and process as a jpeg file with the settings you select when you make the capture, and will discard the raw data if you do not decide to save as raw.
The raw file data remains as is on your computer storage.
This is the reason for saving the raw file from the camera, it allows you to return to these files in the future and process them with new technology or with an alternative application with a different "recipe".
Raw editors embed changes in DNG files, thus physical changes are made to the raw file.
Quote "Raw editors embed changes in DNG files, thus physical changes are made to the raw file."
I am not an advocate of the option to convert raw files to DNG and I am very well aware of all the pros and cons. However whatever changes are made and copied to DNG files is stored in the dng file header. If you are working with raw files with Lightroom the metadata and edits are stored in the Catalog file by default and in xmp sidecar file if you specifically instruct Lightroom to do so, thus leaving the raw file untouched..
DNG is a special case, in that it’s an open format, where other RAW formats are proprietary and must be reverse engineered to decipher them.
Still, a DNG file is a multi-part container that holds the linear-encoded sensor data unmodified in one section, and maintains non-destructive edit information in the form of XMP metadata in a separate section. This is functionally the same as an untouched RAW file together with a sidecar XMP file, but the DNG bundles them together into a single package. The DNG specification even provides for an additional container section into which you can bundle the original RAW proprietary file, and extract it, unchanged, if desired.
So so at the end of the process, if you’re using a DNG-compliant raw editor, it will write its changes to the XMP section of the raw file. But those edits are only useful if you’re interpreting that raw file with another of the very same editor application. Trying to open a Lightroom-saved DNG into another program is not going to give the same results. If you want to send an image to another program, maintaining the look and appearance of your edits, you’ll want to “bake” the changes and export to an image format as suggested above.
Lightroom doesn't create XML sidecars for DNG.
That’s exactly what I said.
@Totallyunstoppable, I did not say that Lightroom creates XML sidecars for DNG,
I said " If you are working with raw files with Lightroom the metadata and edits are stored in the Catalog file by default and in xmp sidecar file if you specifically instruct Lightroom to do so, thus leaving the raw file untouched."
No, you said "Raw processing software applications do not ever make physical changes to the raw files", and that you can store "xmp sidecar file if you specifically instruct Lightroom to do so", neither of which the case. Lightroom doesn't create XMPs for DNG files regardless of your settings.