#!/bin/bash

if [ $1 ]
then
   echo Processing file $1;
else
   for var in `find *.png`;
   do
       echo Processing file $var;
       sips -Z $(($(sips -g pixelWidth "$var" | cut -s -d ':' -f 2 | cut -c 2-) / 2)) "$var" --out "resized_$var" &> /dev/null
   done
fi