Convert images to thumbnails in their own directory

thumbit.py

import os
import platform
from PIL import Image

'''
Run from parent directory.  Folders and files expected in `./files/images`
'''
opsys = platform.system()
if opsys.lower() == 'windows':
    SLASH = "\\"
else:
    SLASH = "/"

last_str = ''

def state_update(str):
    global last_str
    if str != last_str:
        print(str)
        last_str = str

def thumbnailify(path, file):
    '''
    Converts the input image (path) to a thumbnail at the thumbnail path prefixed with `thumb_`
    '''
    global SLASH
    fullpath = path + SLASH + file
    thumbnail_path = f"{path}{SLASH}thumbnails"

    try:
        image = Image.open(fullpath)
        # Convert the image to a thumbnail
        image.thumbnail((200,200))
        # Check to make sure the thumbnail container exists else create it
        if not os.path.isdir(thumbnail_path):
            os.makedirs(thumbnail_path)
            print(f"Created directory: {thumbnail_path}")
        # Assemble full thumbnail file path
        thumbnail_file = f"{thumbnail_path}{SLASH}thumb_{file}"
        # Delete the old thumbnail if it exists
        if os.path.exists(thumbnail_file):
            os.remove(thumbnail_file)
            print(f"Removed old file: {thumbnail_file}")
        # Save the thumbnail
        image.save(thumbnail_file)
        print(f"thumb_{file} created.")
    except IOError:
        pass

def main():
    global SLASH
    # Current PATH to images is where this file is located + \images
    path = os.getcwd() + f"{SLASH}files{SLASH}images"
    state_update(f"Expected image path: {path}")
    # Initialize the directory list
    directory_list = []

    # Scan the directory and get
    # an iterator of os.DirEntry objects
    # corresponding to entries in it
    # using os.scandir() method
    base_path_obj = os.scandir(path)

    # Build a list of directory paths
    for obj in base_path_obj:
        if obj.is_dir():
            directory_list.append(obj.path)

    # Convert each file in the directory list to a thumbnail if the file is a proper image
    for directory in directory_list:
        obj = os.scandir(directory)
        for file in obj:
            if file.is_file():
                fullpath = directory + SLASH + file.name
                img = Image.open(fullpath)
                if img.format:
                    state_update(f"Creating thumbnails for {str(directory).split(SLASH)[-1]}".upper())
                    thumbnailify(directory, file.name)
                else:
                    print(f"Rejecting file: {fullpath} because it is not a proper image file")
            
if __name__ == '__main__':
    main()