In article <456FF787.2060201 at frixxon.co.uk>,
    Paul Williams <paul at frixxon.co.uk>  writes:
  I have post-processed some of those manuals to split
the colours into
 layers, convert them to 1bpp and reassemble. This can make a spectacular
 difference to file size. 
I have some DEC manuals that have this black & red text thing going
on.  What's the netpbm chain you used to split into 1bpp red and black
layers?  That's exactly what I was planning on doing, but its handy to
leverage someone else's work in perfecting the command line :-).
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