code: def get_image_field_display(self, field_name, field):
          
          image = getattr(self.instance, field_name)
          if image:
              fltr, _ = Filter.objects.get_or_create(spec='max-400x400')
              rendition = image.get_rendition(fltr)
              return rendition.img_tag
          return self.model_admin.get_empty_value_display()
docs: Render an image