Find gray scale image and generate a list of them

generate_gray_scale_image_list.py

from PIL import Image
import numpy as np
import argparse
import glob
import sys
import concurrent.futures


def is_gray_scale(path):
    try:
        if len(np.asarray(Image.open(path)).shape) == 2:
            return True
        else:
            return False
    except Exception as err:
        print(f'error at {path}, {err}')
        True


def find_gray_scale_image(path):
    if is_gray_scale(path):
        return path
    else:
        return None


def main():
    parser = argparse.ArgumentParser(description = "Remove only gray scale image file script")
    parser.add_argument("--root", required = True)
    parser.add_argument("--out", required = True)
    parser.add_argument("--image_type", default="JPEG")
    parser.add_argument("--concurrency", default=1)
    args = parser.parse_args()

    root_path = f'{args.root}/**/*.{args.image_type}'
    all_path = glob.glob(root_path, recursive=True)
    print(f'target images count: {len(all_path)}')

    delete_target = []
    with concurrent.futures.ProcessPoolExecutor(max_workers=args.concurrency) as executor:
        raw_result = list(executor.map(find_gray_scale_image, all_path))
        delete_target = [x for x in raw_result if x]

    with open(args.out, "w") as f:
        f.write("\n".join(delete_target))

        
if __name__ == "__main__":
      main()