An example of converting images with asyncio/joblib (just an example, don't use in production)

convert_and_resize.py

import argparse
import asyncio
import time
from concurrent.futures.thread import ThreadPoolExecutor
from functools import partial
from pathlib import Path

import uvloop
from PIL import Image

thread_pool = ThreadPoolExecutor()


def load_and_resize(path, size):
    image = Image.open(path)
    image_resized = image.resize((size, size))
    image.close()
    return image_resized


def save_image(image, path):
    path.parent.mkdir(exist_ok=True, parents=True)
    image.save(path)


async def process_image(image_path, size, output_format, output_dir):
    loop = asyncio.get_event_loop()
    image = await loop.run_in_executor(
        thread_pool,
        partial(load_and_resize, image_path, size)
    )
    output_path = output_dir / image_path.with_suffix(f'.{output_format}')
    await loop.run_in_executor(
        thread_pool,
        partial(save_image, image, output_path)
    )


def get_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('input_dir', help='Input directory with JPEG files')
    parser.add_argument('output_dir', help='Output directory for resized PNG files')
    parser.add_argument('--size', default=1024, type=int, help='Output size')
    parser.add_argument('--output-format', default='png', type=str, help='Output file format')
    parser.add_argument('--input-format', default='jpg', type=str, help='Output file format')
    return parser.parse_args()


async def main():
    args = get_args()
    image_paths = list(Path(args.input_dir).rglob(f'*.{args.input_format}'))
    output_dir = Path(args.output_dir)
    output_dir.mkdir(exist_ok=True)

    start_time = time.time()
    tasks = [
        asyncio.create_task(
            process_image(image_path, args.size, args.output_format, args.output_dir))
        for image_path in image_paths]
    done, pending = await asyncio.wait(tasks)
    assert len(pending) == 0
    elapsed_time = time.time() - start_time
    print(f'Time: {elapsed_time:0.2f} s')


if __name__ == '__main__':
    uvloop.install()
    asyncio.run(main())

convert_and_resize_joblib.py

import argparse
import time
from pathlib import Path

import joblib
from PIL import Image

JOBLIB_BACKEND = 'threading'


def load_and_resize(path, size):
    image = Image.open(path)
    image_resized = image.resize((size, size))
    image.close()
    return image_resized


def save_image(image, path):
    path.parent.mkdir(exist_ok=True, parents=True)
    image.save(path)


def process_image(image_path, size, output_format, output_dir):
    image = load_and_resize(image_path, size)
    output_path = output_dir / image_path.with_suffix(f'.{output_format}')
    save_image(image, output_path)


def get_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('input_dir', help='Input directory with JPEG files')
    parser.add_argument('output_dir', help='Output directory for resized PNG files')
    parser.add_argument('--size', default=1024, type=int, help='Output size')
    parser.add_argument('--output-format', default='png', type=str, help='Output file format')
    parser.add_argument('--input-format', default='jpg', type=str, help='Output file format')
    return parser.parse_args()


def main():
    args = get_args()
    image_paths = list(Path(args.input_dir).rglob(f'*.{args.input_format}'))
    output_dir = Path(args.output_dir)
    output_dir.mkdir(exist_ok=True)

    start_time = time.time()
    tasks = [
        joblib.delayed(process_image)(image_path, args.size, args.output_format, args.output_dir)
        for image_path in image_paths]
    joblib.Parallel(n_jobs=-1, backend=JOBLIB_BACKEND)(tasks)
    elapsed_time = time.time() - start_time
    print(f'Time: {elapsed_time:0.2f} s')


if __name__ == '__main__':
    main()