Oooh, thanks for that. I had read it a long time ago and lost track of it. Now I've added it to my Evernote notebook :-)

Back in the stone age I was a lowly systems guy at the Image Processing Institute at USC and we spent a lot of resources computing all of the noise contributors to a digital camera system. The two uses were creating better cameras (that could compensate for their electronics) and identifying which images came from which camera (which could be used in authenticating an images veracity). These days there is so much post processing done in the camera body I doubt the pattern noise signature can be extracted from an image.