29 Jun
2001
29 Jun
'01
2:14 p.m.
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^)=
Lee.
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29 Jun
29 Jun
3:25 p.m.
New subject: dpi? (was: preserving / ressurecting old docs?
On Sat, 30 Jun 2001, Davison, Lee wrote:
If you make characters that
are a 7 by 9 pixel matrix (the coarsest that
most people will EVER tolerate), how are you going to get 80 characters
per line with less than 70dpi?
In the late 80s, I had to make a lot of the fonts that I needed.
(Cordata and HP compatible soft fonts) When using CX engine laser
printers, at 300dpi, there were DEFINITELY single pixel features at
1/300". 300 dpi is so damn coarse, that you can't even make a GOOD serif.
The entire reason for "hinting" in Adobe Postscript fonts is entirely
because 1/300" is NOT good enough resolution for algorithmically reduced
fonts, and would LOSE features.
I made one font for in-house archiving that consisted of a 7 by 9 PIXEL
(also made a 5 x 7) font mimicing the PC character set at 300dpi. Our
"Fiche font" permitted squeezing a LOT of text onto a page. I could take
what would otherwise have been a few hundred pages, and fold it up and
stuff it in a posket. Every pixel was clear and distinct. The later SX
engines overflowed the pixel cell with each dot, making for a MUCH richer
black, but blurring the pixels together.
(That was before presbyopia set in. Now I need significant optical
assistance to read my old materials.)
--
Grumpy Ol' Fred cisin(a)xenosoft.com
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.
There were and are many POS
printers. Besides, by this time of day, I
can't print a straight line, either.
If a manual
was phototypeset on a CAT phototypesetter . . .
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. 
4:03 p.m.
On Sat, 30 Jun 2001, Davison, Lee wrote:
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.
You're still going to get shitty quality. Why skimp on something that is
supposed to be a preservationary resource for the future?
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.
Your data set is way too limited to be making a valid judgement.
Sellam Ismail Vintage Computer Festival
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cisin＠xenosoft.com -
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Lee.Davison＠merlincommunications.com