17.344 scanning

From: Humanist Discussion Group (by way of Willard McCarty willard.mccarty@kcl.ac.uk)
Date: Mon Oct 27 2003 - 01:53:03 EST

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                   Humanist Discussion Group, Vol. 17, No. 344.
           Centre for Computing in the Humanities, King's College London
                         Submit to: humanist@princeton.edu

             Date: Mon, 27 Oct 2003 06:48:08 +0000
             From: "Jim Marchand" <marchand@ux1.cso.uiuc.edu>
             Subject: scanning

    Francois' point is well taken, but things have changed. There
    was a time when ones scanner offered 150 dpi (dots per inch), but
    now we have digital cameras with many megapixels. I would not
    use a scanner nowadays, but rather a digital camera. With the
    scanner, one has always the possibility of damaging the binding,
    etc., whereas with a camera, one has the possibility of doing
    filtration in real time, seeing the result before `printing',
    etc. Francois' point on analog vs. digital is also good. A
    digital picture is like a pointilliste painting and consists of
    many separate (discrete) points, whereas one has a tendency to
    look upon film as continuous. It is not at all continuous,
    really, and zooming in or enlarging is likely to involve one with
    `grain in the negative' (breakup of the silver salts). The Nazi
    who took the photographs, if he used the best film and camera
    available (say a Leica 35 mm., with Adox KB 14 film, developed to
    a gamma of 7), would still have more of a grain problem than a
    present-day photographer with a 6 megapixel digital camera. One
    needs to keep the analogy of the pointilliste painting in mind.
    Many photographs of yesteryear were printed with a half-tone
    screen and (like the pictures in the Sunday newspaper) are really
    dpi, as you can easily determine by magnifying them.

    Were I the keeper of an archive and wanted to preserve a record
    of my holdings, I would get an SLR (single lens reflex, to avoid
    parallax) 6 (or more) megapixel camera (street price ca. $1000,
    1K) + filters (write the camera company to see what they
    recommend). With a proper stand and lighting, I would make a
    digital photograph of each page, using the proper filter. Look
    at the photograph before you preserve it, with the filter over
    the lens; see what looks best. Record filter, time, etc. I
    would keep the picture in TIFF format. {In CurrentCites 14.10
    (October, 2003), Roy Tennant points out: "As anyone familiar with
    the issue of digital preervation knows, the real problem facing
    those in the field is migration. That is, beinging files forward
    from dead file formats into formats that can be used with current
    software."} TIFF is not going to die. It takes up a lot of space
    in your storage, but that is no longer a problem. What the
    megapixel SLR camera bring us is the ability of a total amateur
    (with care) to take satisfactory archival pictures. Do not
    fiddle with the result, put it in storage. If you want to use a
    program to fiddle with the result, fine, but keep your first
    picture in storage. Above all, do not treat your archival
    pictures with non-algorithmic methods.

    When you take a digital photograph, an LUT (Look-up table) is
    generated, where each pixel has at least the form of f (x,y),
    where x and y are the familiar geometric location (10 over, 9
    down) of the pixel and f represents the gray-level, color,
    whatever, the radiometric information. In general, any fiddling
    with the geometric information could lead to forgery, radiometric
    is ok, ceteris paribus. Every archive in the world ought to
    generate a digital record of its holdings, making it available to
    scholars. Let the scholars do what they will, so long as the
    original is kept. Every record ought to be in TIFF, 6 megapixel
    or more.

    Where artifacts are concerned and 3-D photography is needed, you
    are going to have to go to an expert. Field photography is
    another matter. I could post a bibliography. Do we still have a
    Humanist archive?

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