How to Batch Resize Images in Python with pathlib and Pillow

Batch resize all JPG images from a source folder and save to a destination folder using pathlib and Pillow.

Easy Python 3.9+ Aug 9, 2026 Automation & scripting 12 views 0 copies

pathlib pillow image-processing automation batch
Requires third-party packages — install first
pip install Pillow

Python code

18 lines
Python 3.9+ 
from pathlib import Path
from PIL import Image

def batch_resize_images(src_dir: str, dest_dir: str, size: tuple[int, int] = (800, 600)) -> None:
    src_path = Path(src_dir)
    dest_path = Path(dest_dir)
    dest_path.mkdir(parents=True, exist_ok=True)
    
    for img_path in src_path.glob("*.jpg"):
        if not img_path.is_file():
            continue
        with Image.open(img_path) as img:
            resized = img.resize(size)
            output_path = dest_path / f"resized_{img_path.name}"
            resized.save(output_path)

if __name__ == "__main__":
    batch_resize_images("photos", "photos_resized")

Output

stdout 
No stdout output, but after running the script, the destination folder 'photos_resized' will contain resized versions of every .jpg from 'photos', named like 'resized_photo1.jpg'.

How it works

The function uses Path.glob to find all .jpg files in the source directory, filtering out any non-file entries with is_file(). For each image, it opens the file in a context manager, resizes it to 800x600, and saves with a 'resized_' prefix. The mkdir(parents=True, exist_ok=True) ensures the destination folder exists before writing, making the script idempotent. This pattern is ideal for automation because it handles file paths cross-platform and cleans up resources safely.

Common mistakes

  • Forgetting to import PIL/Pillow, causing ModuleNotFoundError
  • Using `glob('*.jpeg')` when files are .jpg, missing matches
  • Not using `is_file()` and trying to process directories that match the pattern
  • Overwriting original images by saving to the same directory without a prefix

Variations

  1. Use `src_path.rglob('*.jpg')` to include files in subdirectories recursively
  2. Add error handling with try/except to skip corrupt images

Real-world use cases

  • Preprocessing product photos to a uniform size before uploading to an e-commerce platform.
  • Creating thumbnail sets for a photo gallery or content management system.
  • Reducing image file sizes for email attachments or web asset uploads.

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Run locally

This sample needs third-party packages, so it cannot run in the browser IDE. Copy the code above, install the packages shown at the top, then run it in your own Python environment.

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