I'll try to explain myself better.
I scanned my Sony PRS-650 showing the same picture Andy used in the post. Then I scale it with Gimp so the picture now has the same dimension of the photo of JBC (this make a comparison possible).
I scaled Sony PRS-650 200%: it's now a 103dpi resolution
https://www.mobileread.com/forums/att...1&d=1330013098
Andy's JBC Post (I increased contrast for a better comparison):
https://www.mobileread.com/forums/att...1&d=1330013098
and now here you are a picture shows you what I mean ...
https://www.mobileread.com/forums/att...1&d=1330013098
It's clear that the quality is about double => 200dpi
Hope this help