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Subject: Scanning


From: Paul W. Romaine <70541.3427>
Date: Sunday, November 10, 1991
Re: Scanning by Libraries for preservation

In addition to the Cornell project described a week or two ago, Annette
Morris may wish to consult the August 91 and Nov 91 issues of PC
Magazine for reviews of scanning equipment (flat-bed and hand-held
scanners, respectively).  If nothing else, the articles are educational
about the current scope and problems with scanning equipment and
software.  If you contract the scanning, it can be quite expensive.  I
also recall seeing brief reviews of optical character recognition
software (OCR) but can't recall where or when.

Re: Scanning by patrons (ignoring hand-held photocopying)

Dan Traister's query about scanning by patrons intrigued me enough to
ask in the Logitech forum on CompuServe.  Logitech is a major
manufacturer of hand-held PC peripherals, including mice and scanners.
Following are my questions with responses by "Kelly" of the Logitech
Support Group ("*LSG*:").  Material in square brackets are my later
additions.  More detailed responses could possibly be forthcoming by
writing to tech support.

1) Can the pressure from the scanner crush a book's binding or tear or
crumble paper?  More specifically, what the pressure is needed to get an
adequate scan? (Or what range of pressure is needed?)

*LSG*: The hand held scanner unit weighs 300 grams maximum (0.67 lbs).
To scan an image, no additional downward pressure is required. In actual
use, additional pressure is placed on the scanner due to the weight of
your hand.

2) Can the scanner's light cause chemical deterioration or degradation
to the paper and ink?  This comes down to two technical questions: A)
Strength and type of light exposure:

(I'm assuming the type of light used is similar to that used in
photocopy machines--if it is, then a lot of questions can be resolved by
paper conservators.)

B) Minimal amount of time of light exposure (or average) per square inch
(or other unit of measure) to get an adequate scan.

*LSG*: I do not know if the scanner light can cause chemical
deterioration or degradation to the paper and ink. The ScanMan 32 uses a
Yellow/Green LED and the ScanMan 256 [an earlier Logitech scanner model]
used a Red LED. This is not the same type of light a copy machine uses.

There is not a calculated exposure time per square inch for scanning an

3) How easily may photocopies be scanned?  (Assuming a photocopy could
be made.)  I assume that the researcher wants to scan books or other
materials for either image or OCR, but more likely the latter.

*LSG*: Photocopies can be easily replicated. If the image is to be
imported into an OCR package, the photocopied text must be near letter
quality and clear.

Since these questions arise infrequently and address specialized
interests, tech support people aren't too happy to answer them.

Incidentally, the two light-types mentioned by Kelly above are widely
used standards among hand scanners.  Other major hand scanner
manufacturers are listed in the two PC Magazine reviews cited above.
Hope this information, insubstantial as it is, may be of use. My sense
is that special collections will probably use similar rules for scanning
as currently apply for photocopying.  Indeed, there is no reason why
patrons couldn't have clear photocopies to scan rather than originals
since some scanners require repeated scanning.

Paul Romaine

                  Conservation DistList Instance 5:28
                 Distributed: Monday, November 18, 1991
                        Message Id: cdl-5-28-001
Received on Sunday, 10 November, 1991

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