Steve,
As you will often hear on this site, dpi is not really meaningful terminology for those of us editing video. Pixels dimensions are the important numbers we must go by. That being said, a good rule of thumb is that, should you wish to make any meaningful moves on your stills, your imported images neeed to be at least 2-times the size of pixel dimensions of your video. So, when working in 1080, the frame size should be at least 2200 pixels wide.
If your scanning device only indicates dpi, then capture a few stills at various dpi settings and check in Photoshop to see exactly how that translates in terms of pixel dimensions. Then, write down your results and keep that as a handy reference.
David
David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los Angeles
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