preserving / ressurecting old docs?

From: Ethan Dicks <>
Date: Sat Jun 30 21:10:58 2001

--- "Davison, Lee" <> wrote:
> > > Scanning printed material much above 150dpi is usually a waste
> > > as most printing is done at about 70dpi.

Printing on a dot-matrix device, perhaps.

> > What are you smoking, and is there enough for the rest of us?

My reaction exactly.

> We're talking old manuals here. Remember? OLD manuals.

Last time I checked, the alphabet hadn't changed much. Besides, some of
the legends in the drawings are in letters that are very tiny, and there's
always the line art itself... scaning at 70dpi would be next to useless.
> > 600 Dpi with resolution enhancement is very old technology
> > for laserprinters
> >
> Nobody, commercially, makes books on laserprinters.

Excepting my own mother ("Breeches of Silver", which she "typeset"
for the Rev. Richard Starling on her 4Mb Mac SE about 15 years ago).
She did the photo-readies which were sent to a "real" printer for
offset production.

But seriously, no... it's not ordinary to make books on a laser printer,
partially because the ink technology isn't as stable as what is used
in offset presses (reflowed resin, vs. oil-based printing inks).

The resolution isn't the primary issue.

> > If you can manage it, i would say scan at 600 Dpi.
> >
> Waste of time, effort and storage space.

Hardly. With cheap 80Gb disks and CD burners, storage space really
isn't an issue compared with the value of the data. I personally have
a couple of boxes of PDP-8 docs. I have been digging around on
and so far, have only turned up a couple of docs that I have that aren't
up there (and yes, I will be scanning mine at 300dpi if not 600dpi ;-)

> > scanning at 1/2 the target printer resolution is probably
> > the best you can hope for.
> >
> Scanning at just over twice the source resolution is the best you
> will ever get. More than that's a waste.

Information theory suggests that sampling any signal at more than twice
its frequency does not result in aquiring any additional content.

For pictures, I scan at well over the "standard" web resolution of 72dpi,
but I do reduce the scans to approx 72dpi for display on the web (and at
much lower for thumbnails). For printing, I have to agree that 300dpi
is a good compromise between file size and quality. Trying to read the
small print on a DEC maintenance print that has been scanned at 300dpi
is nearly impossible.


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Received on Sat Jun 30 2001 - 21:10:58 BST

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