[PLUG] converting scanned line art to a limited color set

[Galen Seitz]

When working on a design, I print out the schematics using a laser
printer and then make changes on the paper using a red pen.  Then I send
or hand carry my marked up schematics to another person who does the
schematic entry.  What I would like to do is send them my changes via
email, ftp, etc.

I can scan the schematics in binary(B&W) mode, but I lose the red color
of my changes.  If I scan in color I end up with a 6 MB file.  What is a
good way to convert the 6 MB file to a file containing only the three
colors black, white, and red?  I've tried using the quantize function
within imagemagick, but it gives me 3 shades of grey.

thanks,
galen