Make a PDF look like it was manually scanned (#snippet)

I live in Germany, and while many think we have things in order here, we still need to sort out bureaucracy. It's a clu**fu** at best because German officials rely on paper – paper and handwritten signatures.

It can go so far that a scanned document image is preferred over a nice and sharp PDF. I don't own a printer, let alone a scanner, so occasionally, I drag myself to the local copy shop to do official business.

Until now! I've been browsing Hacker News, and the shell script below takes a PDF and makes it look like it's been scanned.

#!/bin/sh
  ROTATION=$(shuf -n 1 -e '-' '')$(shuf -n 1 -e $(seq 0.05 .5))
  convert -density 150 $1 \
    -linear-stretch '1.5%x2%' \
    -rotate ${ROTATION} \
    -attenuate '0.01' \
    +noise  Multiplicative \
    -colorspace 'gray' $2

Side note: the convert command is part of the imagemagick tools and wasn't available on my machine. You might have to install it first. A brew install imagemagick did the trick for me, though.