code: def handle(self, *args, **options):
          
          pks = Image.objects.all().values_list('id', flat=True)
          total = len(pks)
          for idx, pk in enumerate(pks):
              image = None
              try:
                  image = Image.objects.get(pk=pk)
                  self.stdout.write(u'Processing image {0} / {1} {2}'.format(idx + 1, total, image))
                  self.stdout.flush()
                  image.thumbnails
                  image.icons
              except IOError as e:
                  self.stderr.write('Failed to generate thumbnails: {0}'.format(str(e)))
                  self.stderr.flush()
              finally:
                  del image
docs: Generates image thumbnails
  
          NOTE: To keep memory consumption stable avoid iteration over the Image queryset