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

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Subject: Re: [Leica] Scanning
From: "Mark E Davison" <dmark8@qwest.net>
Date: Tue, 24 Jul 2001 09:26:34 -0700
References: <NABBLIJOIFAICKBIEPJJGEHPKLAA.darkroom@ix.netcom.com>

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. Uncorellated scan noise
(either from film grain or electronic noise) makes it hard to distinguish
lines close together--everything looks "fuzzy".  I have witnessed this
myself comparing a 2700 dpi scan of a scene done on a Leica M6 35/2 and
Portra 160 vs. a 1600 dpi scan done on a Mamiya M7 (6 x 7 format) with
Portra 160.

The medium format scan simply had less noise (probably mostly due to
averaging over more grains), and small print on signs in the image was
easily legible in the medium format scans.

Mark Davison

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