Make a 16-page booklet

makepdf.sh

#!/bin/bash

size="3300x2550" # 11" x 8"
# size="3508x2480" # 297mm x 210mm

cvtopts="+append -adaptive-resize $size -gravity center -extent $size -set density 300 -unsharp 0x5+0.3+0"

if [[ ! -z $1 ]]; then
	N=$1
elif [[ $PWD =~ FILE([0-9]+) ]]; then
	N=${BASH_REMATCH[1]}
else
	echo "Cannot determine files"
	exit 1
fi

page() {
  printf "$N-%02d.jpg" $1
}

cvt() {
  a=`page $(($1))`
  b=`page $((17-$1))`
  if (($1%2)); then
    rot=""
    in="$a $b"
  else
    rot="-rotate 180"
    in="$b $a"
  fi
  out="out-$1.jpg"

  echo $in "=>" $out
  convert $in $cvtopts $rot $out &
}

for i in {1..8}; do
  cvt $i
done

wait

convert out-{1..8}.jpg $N.pdf && rm out-{1..8}.jpg