#!/bin/sh
set -e
t=.tmp.$$
pngtopnm "$1" > "$t.pnm"
pngtopnm -alpha "$1" | pgmtopbm -threshold > "$t.pbm"
pnmcomp -alpha="$t.pbm" "$t.pnm" "$t.pbm" "$t.2.pnm"
ppmtowinicon -andppms "$t.2.pnm" "$t.pbm" > "$2"
rm "$t.pnm" "$t.pbm" "$t.2.pnm"