Comment 15 for bug 891586

"Is my theory consistent with your experiments, 2cv67?"

Probably, yes.

If I select 75/150/300/600/1200dpi then I get an identical result which is probably 300dpi.

If I select 2400dpi then I get an error message "Failed to scan. Unable to start scan".
Presumably a memory limit somewhere?
No amount of cropping will change that - I suppose Simple Scan does it's cropping after scanning?

Back in Epson's iScan, then if I try to scan a complete uncropped scanner bed (like in Simple Scan) at 2400dpi then I also get an error message "Selected area is too large for this resolution. Reduce the selected area or resolution"
Because iScan works with a pre-scan > crop > scan method, then I can reduce the area to get a successful scan at 2400dpi, but it is less than 1/4 of the scanner bed size.
I didn't find the exact limit, but it was successful at 7480x10123px (11.1MB).

So yes - your theory seems to fit.

Congratulations for that!