The images plugin is active iff any run has at least one relevant tag.

def is_active(self):
    """The images plugin is active iff any run has at least one relevant tag."""
    if self._db_connection_provider:
      # The plugin is active if one relevant tag can be found in the database.
      db = self._db_connection_provider()
      cursor = db.execute(
          '''
          SELECT 1
          FROM Tags
          WHERE Tags.plugin_name = ?
          LIMIT 1
          ''',
          (metadata.PLUGIN_NAME,))
      return bool(list(cursor))
    if not self._multiplexer:
      return False
    return bool(self._multiplexer.PluginRunToTagToContent(metadata.PLUGIN_NAME))