Python, Django: Автоматический ресайз загружаемых изображений

from io import BytesIO
from uuid import uuid4
import warnings

from PIL import Image, ImageOps, UnidentifiedImageError
from django.core.exceptions import ValidationError
from django.core.files.base import ContentFile
from django.db import transaction


def prepare_avatar(uploaded, bounds=(200, 500)):
    """Return a new JPEG ContentFile; never enlarge the supplied image."""
    if len(bounds) != 2 or any(type(n) is not int or n < 1 for n in bounds):
        raise ValueError('Expected two positive integer dimensions')
    if uploaded.size > 10 * 1024 * 1024:
        raise ValidationError('Размер файла превышает 10 МБ')
    try:
        with warnings.catch_warnings():
            warnings.simplefilter('error', Image.DecompressionBombWarning)
            uploaded.seek(0)
            with Image.open(uploaded) as probe:
                if probe.format not in {'JPEG', 'PNG', 'WEBP'}:
                    raise ValidationError('Разрешены JPEG, PNG и WebP')
                if probe.width * probe.height > 20_000_000:
                    raise ValidationError('Изображение слишком большое')
                if getattr(probe, 'n_frames', 1) != 1:
                    raise ValidationError('Выберите статичное изображение')
                probe.verify()
            uploaded.seek(0)
            with Image.open(uploaded) as original:
                original.load()
                image = ImageOps.exif_transpose(original).convert('RGBA')
                if image.width > bounds[0] or image.height > bounds[1]:
                    image = ImageOps.contain(image, bounds, Image.Resampling.LANCZOS)
                # This site's explicit output policy: JPEG on a white background.
                result = Image.new('RGB', image.size, 'white')
                result.paste(image, mask=image.getchannel('A'))
                output = BytesIO()
                result.save(output, format='JPEG', quality=85)
                return ContentFile(output.getvalue(), name=f'{uuid4().hex}.jpg')
    except (UnidentifiedImageError, OSError, Image.DecompressionBombError,
            Image.DecompressionBombWarning) as error:
        raise ValidationError('Файл не удалось прочитать как изображение') from error


def replace_avatar(avatar_record, uploaded):
    """Application service; caller must authorize this record beforehand.

    AvatarRecord is the application's actual model, with ImageField `avatar`.
    Invoke at the outer transaction boundary, not inside another atomic block.
    """
    model = type(avatar_record)
    prepared = prepare_avatar(uploaded)
    storage = avatar_record.avatar.storage
    new_name = storage.save(f'avatars/{prepared.name}', prepared)
    try:
        with transaction.atomic(durable=True):
            locked = model.objects.select_for_update().get(pk=avatar_record.pk)
            old_name = locked.avatar.name
            locked.avatar.name = new_name
            locked.save(update_fields=['avatar'])

            def delete_old():
                # Do not delete a file still referenced by another record.
                if old_name and old_name != new_name and not model.objects.filter(avatar=old_name).exists():
                    storage.delete(old_name)

            transaction.on_commit(delete_old, robust=True)
        return new_name
    except Exception:
        # Storage and database are not one transaction: clean a failed new file.
        storage.delete(new_name)
        raise