> I always thought that down sampling consisted of some kind of averaging
(of samples).
It SHOULD work that way, if the system (hardware/firmware/driver) is
designed properly. But, just as a note, when doing a pre-scan, I assure
you it doesn't do it at full resolution...obviously, or it wouldn't be so
much faster...
How to tell, possibly, is see how long the scan takes... Scan at the
optical resolution of the scanner, then scan at 1/2 the optical
resolution...see if it takes less time. Providing the data transfer over
the scanner interface to the computer doesn't interfere with the test...I'd
suggest scanning at line art or something that really lowers the data rate,
and then compare the times. An interesting test I'll try on my scanner
when I get the time... Another fly in the ointment is if the downsampling
is done in the driver instead of the scanner... So many variables ;-/
>> But, now
>> that I think about it, if you use a scanner at 1/2 or 1/4 of its full
>> resolution, then the pixel size remains the same but the Nyquist limit
is
>> much lower. Sounds like a recipe for alaising and another good reason
to
>> always scan at higher resolution and average down (not down sample).
