[Django]-Image watermark using PIL in django

Assume you have the server-side url of image as: Photo.image_url

You can use the following view function to return an watermarked image:

from PIL import Image
from django.core.servers.basehttp import FileWrapper
from django.http import StreamingHttpResponse

def render_image_with_watermark(request, pk, text):

    # pk is the primary key of photo model
    photo = get_object_or_404(Photo, pk=pk)

    # watermark the photo and save it to a temp file
    tmp_name = tempfile.mktemp()

    # this function was introduced in:
    # http://www.pythoncentral.io/watermark-images-python-2x/
    add_watermark(photo.image_url, text, out_file=tmp_name, angle=23, opacity=0.25)

    # render the watermarked photo to response
    wrapper = FileWrapper(open(photo.image_url, 'rb'))
    response = StreamingHttpResponse(wrapper, 'image/jpeg')
    response['Content-Length'] = os.path.getsize(photo.image_url)
    response['Content-Disposition'] = 'attachment; filename=photo.jpg'

    return response

In case you want to render all images with watermarked, you can first make the render_image_with_watermark view above has a url:

# urls.py
urlpatterns = patterns('',
    url(r'^photo/(?P<pk>\d+)/$', 'render_image_with_watermark', name='render_image_with_watermark'),
    ...
)

After doing this, try to visit the url /photo/photo.pk，if success, it will render the image directly.

Then, change your showimage.html template:

{% extends 'base.html'%}
{%block title%}{%endblock%}
{%block content%}
{% load endless %}
<div class="container" >
    <div class="row mt" style="padding-top:0px; margin-top:10px;">
        <ul class="grid effect-2" id="grid">
        {% paginate 40 photo_list %}
        {% for photo in photo_list%}
              {% if photo.approved%}
              <li><a href = "{% url 'download_image' photo.id %}">


                     <!-- ATTENTION HERE -->
                     <img src={% url 'render_image_with_watermark' pk=photo.id %} alt = 'sample photo' /></a>

              </li>
              {%endif%}
        {% endfor %}
        </ul>
    </div><!-- row -->
</div><!-- container -->
<p>{%show_more%}</p>
{%endblock%}

Have a try.