Not calibrating just scanners – but calibration of the entire process – as
in a system approach...
I have been working on turning the video migration process into a calibrated
process for 4 years. It hasn’t been easy…. My personal interests and
curiosity has started pulling me into areas of document scanning –
multi-spectral and otherwise. It seems to me that while there are many
people scanning all sorts of things – that in almost all cases there really
isn’t a calibrated process, and that in fact people are relying on the
software within a scanner to “calibrate” the process – when in fact the
software was never really designed to do that – and without an outside and
known reference it is highly unlikely that any such process would really
work or be accurate. Even things as obvious as color temperature – and even
the generation of meta-data associated with the scanning process itself is
pretty flimsy when you really crawl into it. For example – just because a
scanner from vendor X says the lamp is 6400 Kelvin does not mean that ALL of
them are, and there certainly can be variations between different lamps and
even the response over time and ambient temperature can change a lamps
performance over time. So how precisely is that color temperature measured
before / during a scan and at the point of imaging – meaning that sometimes
the lamps themselves expose the object through a platen glass which itself
will of course change color temperature.
Even issues of sensor calibration – can it be said that ALL sensors are
exactly linear with the same response curves? I know this is not the case by
just looking at information that the companies that make the imaging chips
provide.
Which leads me to wonder – it seems that a great deal of imaging is going on
with people using an over the counter consumer type scanner with a process
that is totally uncalibrated. Sure the software tells you it is “calibrated”
but that is nothing more then a simply white balance measured by a histogram
– but that is certainly not a calibrated system the way I think of one.
Am I totally wrong here? Have I missed a few crucial bits of information or
understanding – or even missed the point? Otherwise – it seems to me that
the efforts made heretofore in terms of preservation scanning are really
questionable and allot of work needs to be done in this area before
preservation quality scanning is really something that the field can move
forward with.
Please tell me how I have gone astray in my thinking.
jim
Jim Lindner
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From: Archives & Archivists [mailto:[log in to unmask]] On Behalf
Of [log in to unmask]
Sent: Wednesday, June 14, 2006 10:11 PM
To: [log in to unmask]
Subject: Re: Digitizing Glass Plates
or.... you can scan a hole bunch and then use something like irfan view to
do a batch convert.....
Subj:Re: Digitizing Glass Plates
Date:6/14/2006 6:39:59 PM US Mountain Standard Time
From:[log in to unmask]
To:[log in to unmask], [log in to unmask]
Sent from the Internet
I once had a vendor tell me he could digitize many, many photographs per
hour. It took a fair amount of work to explain why a rotary scanner was not
appropriate for glass negatives and lantern slides.
You'll want to put the images on the scanner emulsion side down -- in
contact with the platen. However, you may wind up with the image laterally
reversed. (Maybe some scanners automatically reverse the image when doing a
transparency.) Be sure to check your model.
-- Richard Pearce-Moses
----- Original Message -----
From: [log in to unmask]
Sent: Tuesday, June 13, 2006 7:59 PM
Subject: Re: Digitizing Glass Plates
Get a scanner that goes up to 4x5 negatives or traspanances..... the
instructions that come with the scanner will be all you need.
Ed Sharpe archivist for SMECC
Good question Allaina; and could anyone tell me where I can find
instructions for digitizing glass lantern slides?
Thanks,
Karen
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Thanks,
Ed Sharpe, Archivist for SMECC
See the Museum's Web Site at www.smecc.org
We are always looking for items to add to the museum's display and ref.
library - please advise if you have anything we can use.
Coury House / SMECC
5802 W. Palmaire Ave. Phone 623-435-1522
Glendale Az 85301 USA
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