[Django]-Programatically populate sample data for Django Image/File fields?

If I understand you correctly you want to use fixtures, basically a JSON formatted file that holds data that will be put into the project database. They can be executed through the django-admin command like :

 django-admin.py loaddata mydata.json

see http://docs.djangoproject.com/en/1.2/ref/django-admin/#loaddata-fixture-fixture