>As a reference here are specs from 3-M who printed the murals on Scotchprint.
25ppi (3mb file) viewed at 15ft or more
50ppi (12.4mb file) viewed at 5 to 15ft.
100ppi (49.4 mb file) viewed at under 5ft.
200ppi (197.8mb file)
400 ppi (791 mb file)<
It's a good point that the sharpness of the image be tied with the viewing
distance. Ours were hand-touchable, so I guess we're talking "in inches."
But this formula seems tied to the specific format- or specificly its DPI.
What resolution was the Scotchprint? Our murals were printed on a format
called Lambda which printed at 200 DPI.