Django. How to add watermark

another_script.py

""" Function for applying watermarks to images.
Original found here:
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/362879
"""

try:
    import Image
    import ImageEnhance
except ImportError:
    try:
        from PIL import Image
        from PIL import ImageEnhance
    except ImportError:
        raise ImportError("The Python Imaging Library was not found.")


def reduce_opacity(im, opacity):
    """Returns an image with reduced opacity."""
    assert opacity >= 0 and opacity <= 1
    if im.mode != 'RGBA':
        im = im.convert('RGBA')
    else:
        im = im.copy()
    alpha = im.split()[3]
    alpha = ImageEnhance.Brightness(alpha).enhance(opacity)
    im.putalpha(alpha)
    return im


def apply_watermark(im, mark, position, opacity=1):
    """Adds a watermark to an image."""
    if opacity < 1:
        mark = reduce_opacity(mark, opacity)
    if im.mode != 'RGBA':
        im = im.convert('RGBA')
    # create a transparent layer the size of the image and draw the
    # watermark in that layer.
    layer = Image.new('RGBA', im.size, (0, 0, 0, 0))
    if position == 'tile':
        for y in range(0, im.size[1], mark.size[1]):
            for x in range(0, im.size[0], mark.size[0]):
                layer.paste(mark, (x, y))
    elif position == 'scale':
        # scale, but preserve the aspect ratio
        ratio = min(
            float(im.size[0]) / mark.size[0], float(im.size[1]) / mark.size[1])
        w = int(mark.size[0] * ratio)
        h = int(mark.size[1] * ratio)
        mark = mark.resize((w, h))
        layer.paste(mark, (int((im.size[0] - w) / 2), int((im.size[1] - h) / 2)))
    else:
        layer.paste(mark, position)
    # composite the watermark with the layer
    return Image.composite(layer, im, layer)


def test():
    im = Image.open('test.png')
    mark = Image.open('overlay.png')
    watermark(im, mark, 'tile', 0.5).show()
    watermark(im, mark, 'scale', 1.0).show()
    watermark(im, mark, (100, 100), 0.5).show()

if __name__ == '__main__':
test()

func.py

for gallery in obj.gallery.all():
  try:
    add_watermark(gallery.media.file, obj.rialtor.water_mark.file)
  except IOError:
    continue

script.py

# -*- coding: utf-8 -*-
import json
from datetime import datetime
from itertools import izip
from decimal import Decimal
import PIL as pil
from PIL import ImageEnhance
import StringIO
from django.contrib.auth import update_session_auth_hash

from django.shortcuts import render, redirect
from django.core.urlresolvers import reverse
from django.db.models import (
    Prefetch, Count, Case, When, IntegerField, Sum, DecimalField, Q)
from django.db.models.functions import Coalesce, Concat
from django.http import Http404, JsonResponse, HttpResponse
from django.conf import settings
from django.core.files.base import ContentFile


def add_watermark(image_file, logo_file, opacity=.8):
    img = pil.Image.open(image_file).convert('RGB')

    logo = pil.Image.open(logo_file)

    # TODO: add aspect ratio as an argument
    base_width = img.size[0] / float(2) * 2
    base_height = img.size[1] / float(3) * 2.5

    base_width = min(base_width, base_height)
    wpercent = base_width / float(logo.size[0])
    hsize = int((float(logo.size[1]) * float(wpercent)))
    logo = logo.resize((int(base_width), hsize), pil.Image.ANTIALIAS)

    # position the watermark
    offset_x = abs(img.size[0] - logo.size[0]) / 2
    offset_y = abs(img.size[1] - logo.size[1]) / 2

    watermark = pil.Image.new('RGBA', img.size, (255, 255, 255, 1))
    watermark.paste(logo, (offset_x, offset_y))

    alpha = watermark.split()[3]
    alpha = pil.ImageEnhance.Brightness(alpha).enhance(opacity)

    watermark.putalpha(alpha)
    pil.Image.composite(
            watermark, img, watermark
    ).save(".".join(image_file.path.split(".")[:-1]) + ".jpg", 'JPEG')