# Scanning papers and converting to pdf's *

Here is how I scan a printed paper and
convert to a pdf file with free Gnu
utilities.

First scan at 300 dpi, as black and white,
and save as separate gif files.  Gif is not
lossy for black and white, and run-length
encoding keeps the files much smaller than
tiffs.  Be sure to frame your page to avoid
bad margins.

All scanner software can do this much.  The
rest requires expensive software (like Adobe
Acrobat) or a few free software commands.
You should be able to install all of these
commands on Windows with cygwin.

I name the images after page numbers, so that
they sort easily: ``01.gif'', ``02.gif'',
etc.

I convert each gif file to a postscript file
with these commands (scripted inside a loop);

=>
  $ giftopnm < 01.gif | pnmtops > 01.ps
  $ giftopnm < 02.gif | pnmtops > 02.ps
...
<=

Then I join the separate postscript files
into a single postscript document with

=>
  $ ghostscript -dNOPAUSE -sDEVICE=pswrite -dBATCH \
       -sOutputFile=combined.ps 01.ps 02.ps [...]
<=

``psmerge'' is simpler but is pickier about
input.  ``ghostscript'' may be available as
``gs''.

Finally I convert the postscript document
into a pdf with

=>
  $ ps2pdf combined.ps combined.pdf
or 
  $ ghostscript -dNOPAUSE -dBATCH -sDEVICE=pdfwrite \
    -sOutputFile=combined.pdf -c .setpdfwrite -f combined.ps 
<=

If you want a pdf file saved as text rather
than as an image, then you will need some
expensive software that performs character
recognition.  You will be obliged to correct
many errors by hand.

Bill Harlan, 2002