I need to save one image than I need to crop it on many images and save to the FK model.
I decided to use post_save signal to save each cropped image.

models.py
class Map(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    title = models.TextField()
    image = models.ImageField(upload_to='map', null=True, blank=True)

    class Meta:
        verbose_name = _('Map')
        verbose_name_plural = _('Maps')


    def __str__(self):
        return str(self.id)


class Tile(models.Model):
    map = models.ForeignKey(Map)
    x = models.IntegerField()
    y = models.IntegerField()
    z = models.IntegerField()
    tile = models.BinaryField(blank=True, null=True)
    image = models.ImageField('Tile Image', upload_to='map', null=True, blank=True)

 	@classmethod
    def create(cls, map, x, y, z, tile, image):
        tile = cls(map=map, x=x, y=y, z=z, tile=tile, image=image)
        tile.save()


signals.py

@receiver(post_save, sender=Map)
def map_saver(sender, instance, k=0, **kwargs):
    import time
    from PIL import Image
    try:
        from StringIO import StringIO
    except ImportError:
        from io import StringIO
    from io import BytesIO
    from django.core.files.base import ContentFile
    from django.core.files.temp import NamedTemporaryFile

    path = f'{settings.MEDIA_ROOT}{instance.image}'
    im = Image.open(path)
    x = im.size[0]
    y = im.size[1]
    for i in range(0,x,256):
        for j in range(0,y,256):
            box = (j, i, j+256, i+256)


            try:
                a = im.crop(box)
                box = list(box)

                for id, item in enumerate(box):
                    item = item // 256
                    box[id] = item

                thumb_io = BytesIO()
                a.save(thumb_io, format='JPEG')
                image = ContentFile(thumb_io.getvalue())
                # Tile.create(map=instance, x=box[0], y=box[3], z=k, tile=None, image=image)
				It doesn't work.



            except:
                pass
            k +=1