Archived posting to the Leica Users Group, 2001/07/24

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Subject: RE: [Leica] Scanning
From: "Austin Franklin" <darkroom@ix.netcom.com>
Date: Tue, 24 Jul 2001 13:55:50 -0400

> Austin Franklin wrote:
>
> >I'd have to think about that, but that does not make sense
> (noise limiting
> the resolution) to me.  Noise certainly does limit the dynamic
> range (which
> is on a per pixel basis), but I fail to see how it limits the resolution,
> which would be across pixels.
>
> Remember that resolution is a measure of how well humans can
> distinguish two
> elements in the image which are close together.

That certainly is one "reference", but not the only reference for
resolution.  The other, that is common, is a film scanner it self, as well
as a camera/film...

> Uncorellated scan noise
> (either from film grain or electronic noise) makes it hard to distinguish
> lines close together--everything looks "fuzzy".

I agree that film grain does, but not necessarily electronic noise.  I don't
see  electronic noise inter-pixel, especially inter-line.  There certainly
is "some" bleed in a CCD scanners red channel, so in that case, I
agree...but I scan almost exclusively B&W, so that is not an issue for me.
No, my scanner does not scan B&W in color, it uses a single ND filter for
B&W scans.

Also PMT (Photo-Multiplier Tube) scanners (drum scanners) do NOT have this
issue at all, since they acquire one pixel at a time...