echo "pdftoppm does not work."
    exit 1
  fi
  convert -thumbnail ${image_size} ${tmp_png_file} "${output_file}"
  rm -f ${tmp_png_prefix}*png
elif [[ x"${cmd_type}" = "ximage" ]] ; then
  check_command convert
  target_file=$(echo "$url" | sed -e "s#^file:/*#/#g")
  convert -thumbnail ${image_size} "${target_file}" "${output_file}"
elif [[ x"${cmd_type}" = "x" ]] ; then
  echo "No filetype."
  exit 1
else