Resize and center crop a directory of images.

resize.py

#!/usr/bin/env python
"""Resize and crop images to square.

Install dependencies: pip install click Pillow

Usage: python resize.py [OPTIONS] --directory /my/image/dir --convert_directory /my/output/dir

Options:
  --directory TEXT          Directory with original images.  [required]
  --convert_directory TEXT  Where to save converted images.  [required]
  --test                    Convert images one by one and examine them on
                            screen.  [default: False]
  -s, --size INTEGER        Size of converted images.  [default: 512]
  -n, --n-proc INTEGER      Number of processes (defaults to all)  [default:
                            0]
  -q, --quality INTEGER     [default: 95]
  --help                    Show this message and exit.

"""
import os
import multiprocessing
from multiprocessing.pool import Pool
from pathlib import Path

import click
from PIL import Image

N_PROC = None
ALLOWED_EXTENSIONS = set([".jpg", ".jpeg", ".png", ".tiff"])
QUALITY = 95


def square_bbox(img):
    w, h = img.size
    left = max((w - h) // 2, 0)
    upper = 0
    right = min(w - (w - h) // 2, w)
    lower = h
    return (left, upper, right, lower)


def convert_square(fname, size):
    img = Image.open(fname)
    bbox = square_bbox(img)
    cropped = img.crop(bbox)
    resized = cropped.resize([size, size])
    return resized


def get_convert_fname(fname, directory, convert_directory):
    return str(os.path.normpath(fname)).replace(
        os.path.normpath(directory), os.path.normpath(convert_directory)
    )


def process(args):
    directory, convert_directory, fname, size = args
    convert_fname = get_convert_fname(fname, directory, convert_directory)
    print(f"{fname} -> {convert_fname}")

    if os.path.exists(convert_fname):
        print(f"File {convert_fname} exists already")
        return

    os.makedirs(os.path.dirname(convert_fname), exist_ok=True)

    try:
        img = convert_square(fname, size)
    except OSError as exc:
        print(f"{fname}: {exc}")
        return

    save(img, convert_fname)


def save(img, fname):
    img.save(fname, quality=QUALITY)


@click.command()
@click.option(
    "--directory", help="Directory with original images.", required=True,
)
@click.option(
    "--convert-directory", help="Where to save converted images.", required=True,
)
@click.option(
    "--test",
    is_flag=True,
    default=False,
    show_default=True,
    help="Convert images one by one and examine them on screen.",
)
@click.option(
    "--size", "-s", default=512, show_default=True, help="Size of converted images."
)
@click.option(
    "--n-proc",
    "-n",
    default=0,
    show_default=True,
    type=int,
    help="Number of processes (defaults to all)",
)
@click.option("--quality", "-q", default=QUALITY, show_default=True)
def main(directory, convert_directory, test, size, n_proc, quality):

    global N_PROC, QUALITY
    N_PROC = n_proc or multiprocessing.cpu_count()
    QUALITY = quality

    os.makedirs(convert_directory, exist_ok=True)

    filenames = list(Path(directory).rglob("*.*"))

    print(f"Found {len(filenames)} files")
    filenames = [
        f for f in filenames if os.path.splitext(f)[1].lower() in ALLOWED_EXTENSIONS
    ]

    n = len(filenames)
    print(
        f"Resizing {n} images in {directory} to {convert_directory} with size {size}."
    )

    pool = Pool(N_PROC)

    args = []

    for f in filenames:
        args.append((directory, convert_directory, f, size))

    pool.map(process, args, chunksize=1000)

    pool.close()
    pool.join()

    print("done")


if __name__ == "__main__":
    main()