Scanning question (Is destruction of old tech docs a moral crime?)

steven at steven at
Tue Jul 23 20:44:57 CDT 2019

Paul etc said
>> On Jul 21, 2019, at 12:16 PM, Jon Elson via cctalk <cctalk at> wrote:
>> On 07/21/2019 05:16 AM, Joseph S. Barrera III via cctalk wrote:
>>> What dpi qualifies as not "crappy"? 300dpi? 400? 600?
>> Most of the text of these documents don't need super high resolution.  But, some contain hand-drawn schematics where an 11 x 17 original has been shrunk to 8.5 x 11" and hand-written signal labels and part types are VERY small.  These need to be scanned at high resolution, with several retries
while adjusting the image threshold to make things readable.>
> Another example that might call for higher than normal resolution is oddball text, where subtle distinctions need to be visible.  An example of this can be found in the scans in the Knuth archive of the THE operating system sources.  Those are line printer listings printed with a typical
medium-worn ribbon -- that's bad enough.  But the printer is upper case only printing mixed-case source material.  That was handled in that OS by overprinting upper case letters with periods.  In a clean original printout that's easy enough to see, but the scans seem to be about 300 dpi and with
that the overprints are often not easy to see.  Since the source text is case sensitive this can be a problem...

I've just put up some oddball text, in this case a few pages of handwritten notes on the main features of
FPL. This was a concurrent task process-control language for the FOX 2, Foxboro's rebadged PDP-11/15 they
sold in the early-mid 70's. I think the notes were written about 1975 or so by someone at the BHP steelworks
where the computer was controlling the fire prevention system in the oxygen plant.

As if the foolscap paper size wasn't a nuisance, the notes are in HB pencil and are _very_ light, in fact I could
only read them properly after I scanned it as TIFFs. The information density on the pages is very low so 150 dpi
worked well enough. I could have spent ages painting out the speckle but it's not worth it, I just wanted it up as
I've not found anything else about FPL anywhere:

Also the brochure on FPL. I did this at 300dpi to TIFF and then output as 8-bit png due to the basic colours they
used (pretty much black, brown and orange tones). I am happy with the result here too:


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