Originally Posted by
Ken Lee
"The optical rez is actually around 840dpi in the width and 960dpi in the length. Anything above this is interpolation.
A scan made at 840dpi upsized to 2400dpi on photoshop and a scan made at 2400dpi look like twins. Same quality. Actually same blurry soup."
When I get home this evening, I am going to try this on my Epson 4990.
My recollection is that others have tested these scanners using resolution targets, and have concluded that when set to 2400 and above, they deliver around 2100 spi.