width=$(identify -format "%w" "$1")
array=(.jpg .png .gif)

for ((i=1; i<=$2; i++)) ; do
    ranselect=$(($RANDOM % 3))
    randomres=$(seq 10 99 | sort -R | head -n 1)
    convert "$1" -resize "${width%??}$randomres" $RANDOM${array[$ranselect]}
done

#Usage: <name_of_script> <name_of_image> <amount_of_copies>
#Example: ./randomize.sh example.jpg 10