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

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Subject: Re: [Leica] Scanning
From: "Mxsmanic" <mxsmanic@hotmail.com>
Date: Tue, 24 Jul 2001 20:05:34 +0200
References: <NABBLIJOIFAICKBIEPJJIEHIKLAA.darkroom@ix.netcom.com>

Austin writes:

> I believe your premise is flawed.  You need to
> sample at slightly more than 2x the maximum frequency
> you want to acquire.  A scanner IS a data acquisition
> system.  53 lp/mm is 106 lines/mm, which, as
> you say, is ~2700 SPI.  In order to assure that
> the scanner can actually "acquire" all the lines,
> both black and white (which is what a line pair is),
> you would need to sample at > 5400 SPI.

No.  2700 dpi is sufficient.  2700 samples per inch = 1350 cycles per inch =
just over 53 cycles (i.e., line pairs) per millimetre.

In reply to: Message from "Austin Franklin" <darkroom@ix.netcom.com> (RE: [Leica] Scanning)