Newsgroups: sci.image.processing
From: paul@pcserv.demon.co.uk (Paul Carpenter)
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!uunet!in1.uu.net!pipex!peernews.demon.co.uk!pcserv.demon.co.uk!paul
Subject: Re: scanner sensor physical structure
References: <3hmqri$qbn@csgrad.cs.vt.edu> <D407sv.KCn@eskimo.com> <3hr21a$40m@solaris.cc.vt.edu>
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Date: Wed, 15 Feb 1995 01:58:48 +0000
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liu@vtaix.cc.vt.edu "Xiangdong Liu" writes:
-kerhop@eskimo.com (Billy Laughlin) writes:
-:Xiangdong Liu (liu@csgrad.cs.vt.edu) wrote:
-:: Hello!  Does anyone know the geometric shape of the (probably CCD) sensors
-:: of commonly used scanners, such as HP ScanJet XX, in terms of coverage of
-:: the picture being scanned?  Is it circular, square, irregular?....
-:: ...sensor spacing, should the sensor output be scaled?  Where can I find
-:: such information?  Thanks!

->I do not such info, but am curious why you are asking about this
->(read: this is NOT a flame about bandwidth waste) and how could this
->info be useful to the rest of us?
->
-I need to simulate the physical scanning process (using a computer program).
.....  It seems I should not consider each sensor
-as an ideal simpling point with infinitesimal area.  Rather I should
-consider the integral of the input over the area covered by a sensor.

The light collecting area of a sampling point in a tube or CCD camera has a 
finite shape and area but only gives a single output for each element, which is 
the integrated (exposure) of that area. Hence *part* of the initial limiting 
factors for resolution, one of the others is the guard distance between the 
areas. There are others, as well as those before and after the sensor as well.

Also remember that all sensors in a line or area device do not perform
uniformly across the sensor or even adjacent photosytes.

-- 
Paul - "Any people you should meet are the products of a deranged imagination"
