[Leica] Preserving digital information

["Mark E Davison" <Mark_E_Davison@email.msn.com>]

In one of our recent debates about digital vs. analog we touched on the
issue of preserving digital information. Although not directly relevant to
Leica rangefinder use per se, I believe that Leica users have an unusually
keen interest in preserving information of all sorts (negatives, prints,
picture databases, product manuals, product literature, articles about
Leica, manuscripts of books that they have written, etc.)  The longevity of
the cameras makes it meaningful to preserve this information for many years.

Since much of this information may be in digital form, it is a good thing to
think about some of the issues surrounding preserving digital information
for the future.

Now it is absolutely true that digital files can be copied perfectly. What
makes digital information fragile is that the stored bits need to be
interpreted by software, and software keeps changing. Therefore, it is not
enough to simply keep copying bits before the physical media they are stored
on wears out (a process called refreshing), you have to keep transforming
the bits into formats that can still be interpreted (a process called
migrating).

As a result, usable digital archives require some degree of constant
attention.

You can reduce the effort required somewhat by storing your bits in slowly
changing, non-proprietary formats, and using platform independent external
media.  For example, you might use CD-ROM as your external media, and store
photographs as .TIFF, rather than in native Photoshop formats. In the
absence of international standards for archival formats, which are supported
by commercially available software, you are essentially betting on what
formats can be read in the future. As a fall back, you need to continue to
archive good old analog artifacts (negatives, prints, manuscripts printed on
archival paper with archival inks.)

A more detailed overview of the problems, from the standpoint of research
librarians, can be found in a white paper at the following web site:

http://www.rlg.org/ArchTF/index.html


Disclaimer: although I have been a software engineer for some ten years, I
am not a professional expert in archiving digital media, so I will eagerly
confess to appalling ignorance about the subject, on many levels.

Hope this information helps some of you.

Mark Davison