conv.sh

#!/bin/bash

# generate a random 12-character string
output_dir="output"

# create the output directory
mkdir "$output_dir"

# loop through all the .jpg and .png files in the current directory
for file in *.jpg *.png *.jpeg; do
  # get the file extension
  ext=${file##*.}

  # check if the file is a .jpg or .png
  if [[ "$ext" == "jpg" || "$ext" == "png" || "$ext" == "jpeg" ]]; then
    # resize the image to fit within 640x480 and save it as a .png file in the output directory
    convert "$file" -resize 640x480 "$output_dir/$(cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 12 | head -n 1).png"
  fi
done

# loop through all the .png files in the output directory
for file in "$output_dir"/*.png; do
  # run the "optipng" utility on the file to optimize its size
  optipng "$file"
done