Brad Jensen wrote:
I said:
>> Depending on the format that may be all you get. If the file
>> was saved in a documented format like Open Doc, and that
>> format has been maintained, and If the user has a current
>> version of the filters and IF they can tell from the metadata
>> that the document may be of interest.
>> Then the digital document may unfold with perfect clarity.
>> If any of the links are broken, it is just so many almost
> random bits.
>
And Brad said.
> That is untrue. I speak as a person who has written numerous
> conversion programs for documents in unknown formats. If the
> information is there in digital text format, in either ASCII or
> EBCDIC, it is generally possible to reconstruct the document
> text.
>
>> Note that a Microfilm copy even if scratched and bent,
>> suffering for Vinegar Syndrome, Re-dox and too much
>> thiosulphate, can probably still be read. at least enough to
>> see if you want to treat those problems. A damaged - or
>> unsupported format digital document may not give that freedom.
>
> It is far, far easier to do a digital conversion of a digital
> document, than build a special piece of equipment to convert an
> analog recording of some kind. And since the document is digital,
> it can be passed around at no incremental cost to many people who
> might have both the interests and capabilities to do so.

I am not wanting to sound like I am arguing, and I relaise that I might
8) What I am trying to get across is that a digital documnet
(picture/sound/text) requires that it come iwth metadata and that either
the documnetation for the format is available so that It can be
converted to whatever is in Vouge at the time it is wanted to be refered
to, or as you point out someone has to reverse engineer whatever format
it was placed in. perhaps easy for .BMP files slightly more dificult if
in more complicated formats, (think DRM enabled WMF for example)


>> As far as Video, "Film", audio and other data, again they can
>> only be used if the format is known. and if the playback
>> equipment is available or can be faked.

The point I was making is that if I pick up a piece of film, and hold it
to th elight I can see that their is information their, and just need to
get out a lupe to be able to identify if it is relivant to what I am
searhing for,. I have a 16mm film beside my computer and I can easaly
read the title card, almost with my bare eyes. The sound ( analog)
might take some effort to read off without a projector. If it was 35mm
Sound with Dolby Digital track, I would have to know a lot about the
proprietary dolby process for that track to be anything other than a
checkerboard of cyan coloured dots.

> Again, this is untrue. When an image is converted to digital, it
> becomes one of a small subset of values : on off bits, 0-255 grey
> level, or individual color level values (typically three bytes,
> 0-255 of red, green, or blue). The various image formats compress
> those values in different ways, and use different algorithms for
> motion encoding. But if you scan an image of a document page at
> 8-bit grayscale, it will be digitally recoverable and legible ten
> thousand or a hundred thousand years from now.

I belive that JPG can encode greater colour depth than 8 Bits. you
wouldhave to know or guess the format to undo the compression.

>
> No scratches, no fading, no deterioration of any kind. And while
> there was a lot of ad-hoc experimentation with formats in the
> early days of imaging, this has really settled down. You can
> expect a JPG to be readable by current software a thousand years
> from now, even if it is not the method currently used for picture
> taking.


That leads me into parttwo of my waries about digital documents. I used
to have bell express vu satalite TV. When the rain came the link would
start to drop bits, The picture would disolve into a buch of squares
before the system would give up and switch to a card that said "aquiring
Satalite" Even a small disruption totaly broke up the picture or sound.

Now if a digital documnet can be stored withOUT having some of the bits
changing, then ideed it should come out fine. That also maens that the
media can be changed any number of times - as long as the copies are
bit-for-bit, without degrading the documnet .. BUT droping a few bits
which is a silamar addition of noise happened in an analog system might
degrade the picture slightly and add his to the sound, may make the
digital documnt completly unreadabel. My Wife who retired from Doing
Speech Coding just says the "technology is brittle"



>
> But the film has a finite lifetime. Digital data is eternal. It
> does not decay.

If it can be sucessfully replicated as the media that holds it starts to
break down. The analog media curently is holding up for 50-100 years.
Some folks figure that Digital data must be migrated every 5.



>
> Digitizing makes media universally available to each of the
> billions of people in the world who has access to the Internet.
> It reduces the cost of copying and transferring the media
> (including documents) to near-zero. It makes the information
> electronically searchable, which makes it far more useful. And it
> eliminates the degradation of the content over time to zero.


I will agree that having current information in digital form handy is
great. When I shoot my Famialy snapshots I aways have the lab made a
cd. and more folks see the CD picture than will likly ever see my
albums. I do have the expectaion that if I need those shots in 10
years, that the original film will be the resource that I turn to ....
except for the ones that I have in my curent public pages where their
are backed up by more than myself.


> The only reasons I can think of for not digitizing are
> unfamiliarity with the technology, and nostalgia. It is
> understandable that nostalgia might be forgiven archivists - but
> your own successors will not forgive you.

I am not saying not to make digital copies, but mearly to exercise due
diligence and also keep analog media. I think we are comming full
circle here, but Both Fuji and Kodak have gismos that will act as
printers on your computer and allow you to make a Silver Microfilm copy
of anything you might be able to print on your PC. Yes the PC copy is
much more convenient to use and change, but the Silver copy will last at
least 100 years. (acetate has lasted at least half that long even when
after they discovered VS.) and polyester looks more promising.

--
Charles MacDonald Stittsville Ontario
cmacd@... Just Beyond the Fringe
http://www.TelecomOttawa.net/~cmacd/
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