scan for posterity?

[JQ Johnson]

Roy Tennant writes:
>I would be perfectly happy to never digitize something twice

Although I agree that the cost of rescanning needs to be taken into
account when deciding whether to scan at high res, note that even the best
laid schemes gang aft a-gley.  In particular, scanning at 600dpi in 3
colors (30 bit) isn't going to capture a lot of information in the
original that scanners 30 years from now will pick up and that may be
important to people then.  One can easily envision scanners that scan at
more wavelengths (note that PRINTING these days is often 6-color because
3- and 4-color don't reproduce the subtle differences that people
perceive), at arbitrarily higher resolutions (scanning for glossy printing
is today often at 1200dpi [optical] or higher), that pick up surface
texture directly, that measure polarization, ad nauseum.  Depending on the
type of original, of course -- a collotype is not the same as a 35mm
slide.

It's important to ask the question of what you're planning to use the
image for, to ask what you are likely to use it for 5 years from now, and
what the cost of rescanning would be.  So as a practical matter I often
follow Roy's advice, even for personal photos to be published on the web.
But I'm not at all convinced that "scan for posterity" in the library
archival sense, where archives are expected to be useful for centuries and
to meet currently unpredicted needs, is feasible in most cases.  I'm not
saying "don't do it"; the grainy black and white photo in my art text from
the '60s is still useful to me.  Just "try to preserve your originals" and
use a discount rate in your cost/benefit calculations that assumes the
value of your scan won't be very high a decade or three from now, no
matter what you do.

JQ Johnson                      Office: 115F Knight Library
Academic Education Coordinator  mailto:jqj at darkwing.uoregon.edu
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