Another shitty example :)

image_recursively.py

from PIL import Image
from os import path as p
import os
import argparse

def process_image(im):
    size = im.size
    menor = min(size)
    return im.crop((0,0,menor,menor)) \
             .resize((256,256)) \
             .convert("L")

if __name__ == "__main__":
    parser = argparse.ArgumentParser(
                    prog='Converter',
                    description='Converts images for Neural Network input',
                    epilog='')
    parser.add_argument('src_dir', help="Source directory")
    parser.add_argument('dest_dir', help="Destination directory")
    parser.add_argument('-c', '--create-dest', action='store_true',
                        help="Create destination directory, default is False")
    args = parser.parse_args()

    src_dir = args.src_dir
    dest_dir = args.dest_dir

    if not p.isdir(src_dir):
        print(f"Source directory \"{src_dir}\" does not exist")
        exit(1)
    if not p.isdir(dest_dir):
        if args.create_dest:
            os.mkdir(dest_dir)
        else:
            print(f"Destination directory \"{dest_dir}\" does not exist")
            exit(1)


    for root, dirs, files in os.walk(src_dir):
        for filename in files:
            f = p.join(root, filename)
            im = Image.open(f)
            im = process_image(im)
            
            rel = p.relpath(f, start=src_dir)
            dest = p.join(dest_dir, rel)
            os.makedirs( p.dirname(dest), exist_ok=True )
            im.save( dest )    

images.py

from PIL import Image
from os import path as p
import os
import sys

def process_image(im):
    size = im.size
    menor = min(size)
    return im.crop((0,0,menor,menor)) \
             .resize((256,256)) \
             .convert("L")

if __name__ == "__main__":
    if len(sys.argv) != 3:
        # TODO: Handle this properly using argparse
        print(f"USAGE:\n\t{sys.argv[0]} SOURCE_DIR DESTINATION_DIR")
        exit(1)
    src_dir = sys.argv[1]
    dest_dir = sys.argv[2]

    if not p.isdir(src_dir):
        print(f"Source directory \"{src_dir}\" does not exist")
        exit(1)
    if not p.isdir(dest_dir):
        print(f"Destination directory \"{dest_dir}\" does not exist")
        exit(1)
    infiles = [ p.join(src_dir, i) for i in os.listdir(src_dir) ]
    print(infiles)

    for f in infiles:
        im = Image.open(f)
        im = process_image(im)
        filename = p.basename(f)
        im.save( p.join(dest_dir, filename) )