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Informed Discussion of Beekeeping Issues and Bee Biology

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Subject:
From:
James Ralston <[log in to unmask]>
Reply To:
Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Wed, 1 Aug 2001 18:57:51 -0400
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On Wed, 1 Aug 2001, David L. Green wrote:

> Optical format is the longest lasting; most likely it will outlast
> us; whether we will still have the devices to read it is the
> question, as technology moves on.  But burning CD disks is the most
> permanent storage we have available for home use today. Fortunately
> its the cheapest storage as well.  So get your good shots on a CD
> ASAP.

The chance that CD-R media will degrade before a better archive
storage medium becomes available (and we have to convert all of our
archives) is relatively slim.  Most CD-R manufacturers claim a shelf
life of between 50 and 100 years for CD-R media under typical office
conditions (controlled heat and humidity).  I'd guess that it'll take
no more than 10 years (if that) for CD-R to cease to be a preferred
archive storage medium.

Note the "typical office conditions" part, though.  If you store your
CD-Rs in a trunk in your (alternatively) sweltering and freezing
attic, you might be in for a nasty surprise when you take them down in
a few years and try to read them.

> It is important to either save your master copy, unedited, or a TIF
> version of the same.  JPG (which is becoming the most common format
> for digital cameras) and other photo formats compress the image to
> save file space.  However this causes some loss of information as
> well.

A more detailed explanation of JPEG can be found here:

    http://www.faqs.org/faqs/jpeg-faq/part1/

Excerpting the JPEG FAQ isn't appropriate for this list, but I would
recommend that anyone who deals with JPEG (i.e., images produced by
digital cameras) read the FAQ.  (In particular, pay attention to
question #10; if all you want to do is crop the picture your digital
camera produced, you can do it by a multiple of the JPEG block size
without introducing any further loss *if* your image editing software
knows how to do it.)

> So always save the original master or a TIF copy, and do your
> editing from it each time, but don't save it in such a way as to
> overwrite the master.  That's one of the advantages of writing a
> copy of the original to a CD-R disc, which cannot be overwritten by
> mistake.

Repeatedly reading from a CD-R may shorten its shelf life.  (The jury
still seems to be out on this one.)  At the minimum, increased
handling increased the chance of accidental damage (dropping it,
flexing it, etc.).  Therefore, it's probably a good idea to read from
discs you consider to be archives as little as possible once you've
burned them.

--
James Ralston
Pittsburgh, PA, USA

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