on 6/27/02 6:56 PM, John A. Lind at jlind@xxxxxxxxxxxx wrote:
> At 17:48 6/27/02, Jim Brokaw wrote:
>
>> A careful digital scan, capturing as much of the data off the film as is
>> possible, then preserved in a recoverable format, can be a much longer-lived
>> archive.
>
> Note: This is *not* "picking on" Jim Brokaw but discusses the greater
> issues of digital computing and data storage, a very real and serious
> problem studied by a former employer and a major topic in my graduate
> studies (which were *not* computer science).
Well, I guess I need to step up and *not* defend myself... my intention with
my post is to suggest that digital archives, properly maintained, may be as
archival or long-lasting as film archives. This has turned into an
interesting conversation...
>
> I won't discuss the medium on which CD's are recorded. That's another
> issue entirely, but I seriously doubt the "common" CD has an archival life
> as long as properly stored transparencies or B/W negatives (color negatives
> are another problem).
You are correct in that recordable CD's use dye technology, although not in
exactly the same way as film, as I understand it. In film, the dye clusters
form the actual image data. In CD's, as I understand it, the dye functions
as a surface that is changable by laser/magnetic interference at points as
desired; by changing a series of points a digital chain of changed/unchanged
areas creates a binary record. The data is contained in the order of the
chain of changed/unchanged areas. Articles I have read suggest a lifetime of
30-50 years or more for a CDR stored in a normal indoor environment. For as
long as the CD is readable, though, the entire lot of the data will be
readable (as I choose to define 'readable' i.e. recover the original data in
full) thus enabling the reconstruction of the original image without loss of
its integrity as it was stored originally.
A film archive, stored under equal conditions, may last as long, but analog
media are subject to continual, gradual degradation short of 100 0ata
recovery. I discovered this when I scanned some (not particularly carefully
stored) color negatives from ca. 1975 recently... I found some ringlike
structures which looked like cousins to lens fungus... correcting the
problem (by cloning unaffected image areas) took some time. I doubt the
actual negative's damage is reversible. Film archives stored for posterity
need careful maintenance, continued oversight to make sure that temperature
and humidity limits are respected and maintained. Even with this care, time
will cause gradual image degradation resulting in image data loss.
>
> IMHO digitizing film imagery for long term archival (many decades) is is a
> myth being served up by the market-droids of the digital hardware and
> software manufacturers. Imagine having digital files stored on 8" floppy
> disks. How are you going to read them? Even if you *could* find an 8"
> floppy drive, where is the machine running CP/M to read the file directory
> and allocation table? Then there's the file format itself, and the
> lifespan of the magnetic medium and its base material (more accurately, how
> the magnetic material adheres to the base material). All this occurred in
> less than **half** the age of my father's Kodachromes. Heaven forbid you
> have something on digital tape!!
Digital archives need continued maintenance as well, to insure that the
media and data formats are still readable (both physically-readable and
software-readable). This will necessarily include upgrading to newer media
materials and data formats as they are developed (which will happen faster
than new methods of securing temperature/light/humidity control are
developed). The only thing that can be said for this is that while a digital
archive image is actively maintained there can be 1000f the original image
data updated and transferred to the new medias and formats. Even careful
preservation of optimal storage conditions for film archives only slows and
reduces the image degradation over time.
>
> We did a study about at the aerospace company I worked for in California
> about the "half-life" of digital computer technology. It's approximately
> seven years. Why? Because our customer(s) wanted to buy systems that
> would be usable and supportable for several decades. The sad story is
> digital computing platforms cannot be easily supported after about 5-10
> years. If the digital computer industry (hardware *and* software) had
> their way, it would be shorter yet, to **force** buying new hardware and
> software (from them) and maintain a constant revenue stream. Think of it
> like a subscription that requires renewal about every 5 years or so. How
> long ago was it that the average PC was a Pentium processor under 200 MHz
> running Windows 3.1 or perhaps Windows '95? If you wrote something in
> WordStar Word Perfect ten years ago, how would you access it now? If you
> did some financial studies or pro forma balance sheets in Lotus 1-2-3 to go
> with it, how would you access it now? Do you even have a disk drive that
> can read the disks on which it was stored (if it was 5.25 inch
> mini-floppys, you're sunk).
>
> IMPORTANT INFO ABOUT "CD" TECHNOLOGY:
> CD technology is sunsetting. It's being replaced by DVD. All those who
> have been busy archiving gigabytes of data on CD's, get ready to copy it
> all from CD to DVD in the not too distant future. Keep the CD's well
> organized. Finding a CD somehow got missed a few years after all the
> legacy data conversion is accomplished and can no longer be performed could
> be heart-breaking. The larger the data archive, the more arduous legacy
> data conversion becomes. This is a Big Deal for major corporations, and
> they have an IS department with the trained personnel and tools for it!
>
> I can hold a CD up to the light and wonder at all the pretty rainbow
> reflections that scatter from its surface, but I cannot read a single file
> on it with my eyes. I can hold a Kodachrome transparency up to the light
> and wonder at how well my father was able to estimate exposures and compose
> his photographs over 50 years ago.
>
> -- John
I would never advocate scanning slides or negatives and then discarding the
originals. I think you should maintain the originals as well as you can, and
also make a digital archive of the originals when they are fresh. Updating
the digital archive as digital technology evolves, as well as maintaining
properly archival storage conditions for your film archives, will insure
that you have the best of both archive techniques. You will have a 100%
recoverable digital archive of the image, as well as the film original that
can at some future date (as scanning technology and processing software
evolve) be rescanned for further image recovery. It is possible that those
50-year old Kodachromes, scanned with a state-of-the-2050-art scanner and
processed with Photoshop v.27.2.5 on your Dodechedrium-17 PC will yield
better digital images than you will have in your (by then quad-density
optical-hologram memory cube) archive of the patiently transferred and
maintained image scans you made on the quaint technology of 2002. But 100%
of the digital image information scanned in 2002 will still be there in 2050
in those properly sustained digital archives.
While this discussion has academic interest for most of us, I wonder how
NASA is preserving the original images of the moon landings, etc...? I would
suggest highest quality digital scans, and then also archive the color
information from the color negatives/slides to black & white RGB-filtered
images, thereby changing the color dye information into monochrome silver in
emulsion information. This probably is longer lasting than color chemistry,
as Matthew Brady's Civil War negatives suggest. Reassembly of the black &
white negatives could reconstruct the color image without any color shifts
due to dye changes over time... I don't think any of us have images that
have such historic importance, but certainly those images do exist. I'm sure
there have been serious processes evolved to preserve these for posterity as
well as is possible.
Of course, in 2050 we'll all be trying to find the last rolls of that
old-fashioned discontinued 35mm film, in order to keep using our antique OM
cameras and old glass lenses... good luck getting meter batterys... <g>
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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