Whisky-dave
Do you happen to know whether or not this preview file is a copy of the original file but 'rendered' at 72DPI rather than the final copy which is mostly likely to be 300+ DPI for printing ?

nospam
there is no dpi or more accurately ppi until you print. everything is always done to the original image.

Floyd L. Davidson
Until you print... or display an image on a monitor screen. Same thing, and a different value for DPI/PPI.

Sandman
Now Floyd thinks the DPI information saved for an image file is in any way related to the physical PPI of the screen. Isn't he adorable?

Floyd L. Davidson
The only one who said anything about "saved for an image file" is YOU!