#!/bin/sh -e

for a in "$@"
do
  extension="$(printf "$a" | tail -c 4)"
  output_dir="$(dirname "$a")/split"
  output="$output_dir/$(basename "$a" "$extension")"
  mkdir -p "$output_dir"
  convert "$a" -crop 50%x100% +repage "$output-%d.jpg"
done