#!/bin/bash

MASKDIR=aloi_mask4
OUTPUTDIR="output/aloi_mask4_eroded"

function createfolders {
   if [ -e ${OUTPUTDIR} ]
   then
      rm -r ${OUTPUTDIR}
   fi
   
   mkdir ${OUTPUTDIR}

   for i in `seq 1 1000`; do
      mkdir ${OUTPUTDIR}/${i}
   done
}

createfolders

for i in `seq 1 1000`; do
   for j in $(ls ${MASKDIR}/${i}); do
      convert ${MASKDIR}/${i}/${j} -morphology Erode Octagon  ${OUTPUTDIR}/${i}/${j}
   done
done

cd $MASKDIR
find . -name "*.png" | parallel -eta convert {} -morphology Erode Octagon ../$OUTPUTDIR/{}