bash: extract high-res images from pdf using imagemagick (recursively)

fromPdfToJpg

#!/bin/bash
# extract jpg from PDF
# based on a script edited by Purch
#####################################

if [ -z $1 ];then echo Give target directory; exit 0;fi

find "$1" -depth -name '*.pdf' | while read file ; do
        directory=$(dirname "$file")
        oldfilename=$(basename "$file")
        newfilename=$(echo "$oldfilename" | sed 's/.pdf/.jpg/g')
        if [ "$oldfilename" != "$newfilename" ]; then
                convert -density 600x600 "$directory/$oldfilename" "$directory/$newfilename"
                echo ""$directory/$oldfilename" ---> "$directory/$newfilename""
                mv -i "$directory/$oldfilename" "$directory/$oldfilename.done"		
                #echo
        fi
        done
exit 0