check_command() {
  cmd=$1
  cmd_path=$(command -v "${cmd}")
  if [[ ! -e "${cmd_path}" ]] ; then
    echo "${cmd} does not exist."
    exit 1
  fi
}

# Get ImageMagick command (magick for v7, convert for v6)
get_imagemagick_cmd() {
  if command -v magick >/dev/null 2>&1; then
    echo "magick"
  elif command -v convert >/dev/null 2>&1; then
    echo "convert"
  else
    echo ""
  fi
}