I recently worked on the re-design of 2 Degrees, which required a lot of image processing on thumbnails. The thumbnails where to be in a variety of different sizes, all with rounded corners and keylines on a selection of virtually identical off-white backgrounds and gradients. And they all had to work on IE6 *spit* without the transparency hack.

A variety of thumbnails generated by Sore Thumb

A lesser engineer may have told the front-end developer where to stick his rounded corners, but I didn't want see a grown man cry, so I built Sore Thumb, an on-the-fly thumbnail and image processing system for Django.

Sore Thumb uses a declarative method of defining thumbnails, similar to Django's model and form definitions. Here's an example of how to declare a thumbnail processor that produces a 120x100 pixel thumbnail with 10 pixel rounded corners and a dark grey keyline:

from sorethumb.djangothumbnail import DjangoThumbnail
from sorethumb.filters.defaultfilters import ThumbnailFilter
from sorethumb.filters.drawfilters import RoundedCornerFilter

class RoundedCornersEdged(DjangoThumbnail):
    format = 'png'
    filters = [ThumbnailFilter(120, 100),
               RoundedCornerFilter(10, border='#333')]

Once this class has been imported, the thumbnail processor will be available in templates via the sorethumb filter which takes a Django FileField and returns the url to the thumbnail.

For example:

{% load sorethumb %}

<img src="{{ profile.photo|sorethumb:"rounded_corners_edged" }} />

You will also need to add sorethumb to your INSTALLED_APPS for this to work.

That's pretty much all there is to working with Sore Thumb, see these examples for inspiration and the documentation for the details.

You can install sorethumb with easy_install, PIP, or directly from source:

easy_install -U sorethumb

Please let me know what you think of Sore Thumb. I'd rather not spend too much time maintaining it, but since most of the code has been in production for a number of months already, there shouldn't be many changes required. If you have any feature requests or bug-reports, now would be a good time to raise them while I have the time to do the work!