resize every jpeg in a dir into subdirs by size

resize.sh

#!/bin/bash

sizes=("3000" "1500" "1000" "750")

for size in "${sizes[@]}"; do
  mkdir $size

  for i in *.jpg; do 
    magick "$i" -resize ${size}x${size} -density 300 -units PixelsPerInch "${size}/${i}_${size}_300.jpg"
  done

done