A simple python script for making a .npy file of images, given the directory of the images.

make_npy_arr.py

"""
    It prepares and saves .npy array to the specified path.
"""

import os
import numpy as np
import sys
from PIL import Image
from tqdm import tqdm
import argparse

parser = argparse.ArgumentParser(description="Saving images as a numpy .npy file")
parser.add_argument("images_dir", type=str)
parser.add_argument("output_path", type=str)
parser.add_argument("-n", "--number_of_pixels", type=int)
parser.add_argument("-v", "--verbose", action="store_true")
parser.add_argument("-z", "--save_compressed", action="store_true")
parser.add_argument("-c", "--add_channel_dim", action="store_true")
args = parser.parse_args()
#
assert os.path.isdir(args.images_dir), "The images directory is invalid."
images = []
for i in tqdm(os.listdir(args.images_dir), ascii=True):
    if i.split(".")[-1] == "png":
        images.append(np.array(
            Image.open(os.path.join(args.images_dir, i)).resize(
                (args.number_of_pixels, args.number_of_pixels)
            ), dtype=np.uint8
        ))
images = np.stack(images, axis=0)
if args.add_channel_dim:
    images = np.expand_dims(images, axis=1)
if args.verbose:
    print(f"An array with {images.shape} is preapred and being saved at {args.output_path}.")
if args.save_compressed:
    assert args.output_path.split(".")[-1].lower() == "npz", (
        "For saving file in compressed format, output path must have npz extension"
    )
    np.savez_compressed(args.output_path, images)
else:
    np.save(args.output_path, images)