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
Media Matters LLC. is a technical consultancy specializing in archival audio and video
material. We provide advice, analysis, and products to media archives that
apply the beneficial advances in technology to collection management.
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
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