+ ( . "./$1.sh" || exit
+ case $TUPLTYPE in
+ GRAYSCALE_ALPHA) $PAMCHANNEL -infile "$1" 1 > "$1.alpha" ;;
+ RGB_ALPHA) $PAMCHANNEL -infile "$1" 3 > "$1.alpha" ;;
+ *) rm -f "$1.alpha" ;;
+ esac
+ ) || return
+
+ if test -e "$1.alpha"; then
+ $PAMARITH -and "$1" "$1.alpha"
+ else
+ cat "$1"
+ fi
+}