#!/bin/sh
[ $# -ne 0 ] || { echo "usage: tiffinv file"; exit 1; }
tmpfile=$(mktemp ~/.tiffinv.XXXXXX) || exit 1
tifftopnm "$1" | pnminvert | pnmtotiff -g4 >$tmpfile
mv -f $tmpfile "$1" && chmod go+r "$1"
.