preserving / ressurecting old docs?

From: Davison, Lee <>
Date: Fri Jun 29 21:14:39 2001

> 70 DPI would be something like a 9 pin dot matrix printer.
The definition on those 9 pin dot printers is about 100dpi but the
resolution is much less, possibly less than 50 dpi. The Transtel
printer here is lucky if it can print a straight line.

> If a manual was phototypeset on a CAT phototypesetter (most
> popular phototypesetter in the publishing industry in the mid
> 70's.) then the resolution is 2000dpi (they spec it in lines/
> millimeter but my recollection is that it was about 2000lines/
> inch after conversion) so those manuals should be scanned at
> 4800 dpi right?
No, the resolution may be 2000 lines/inch, the definition won't be.
I doubt you'll find any feature, even on good copy, smaller than
1/250". On old manuals I would be suprised to find much, if any
detail smaller than 1/100" so ok. 250dpi then.

> Basically, I think you may be mistaken on a few of your numbers.
Not really, just looked a two books, TI TTL data book 1979 and
Radio valve data 1966. The TI book gets to about 125 dpi at best,
but is on coated paper. The Radio valve data book barely manages
80 dpi and is on uncoated paper, typical for manuals.

>Scanning at just over twice the source resolution is the best you

Hmmm ... for "resolution" read "definition" .. well it is 3AM. 8^)=


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Received on Fri Jun 29 2001 - 21:14:39 BST

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