#!/bin/sh

usage()
{
    echo "usage: $(basename $0) [-i] file" >&2
    exit 1
}

while getopts ":i" c
do
    case "$c" in
    i)      integers=1;;
    :|'?')  usage;;
    esac
done
shift $(($OPTIND - 1))
if [ $# -lt 1 ]; then usage; fi

tiffinfo "$1" | nawk -v integers=$integers '
/^  Resolution:.*\(unitless\)/ {
    pos = match($0, /[0-9]+, [0-9]+/)
    aspect = substr($0, pos, RLENGTH); sub(/,/, "", aspect)
}
END {
    if (! aspect) { print integers ? "1 1" : "1"; exit }
    if (! integers) { split(aspect, f); aspect = f[2] / f[1] }
    print aspect
}'
.