process_file/png2ico.py

from PIL import Image

def convert_png_to_ico(png_path, ico_path):
    image = Image.open(png_path)
    image.save(ico_path, format='ICO', sizes=[(16, 16), (32, 32), (48, 48), (64, 64)])

convert_png_to_ico('icon.png', 'icon.ico')