def imageFields(self):
        """
        Returns field names of image columns.

        :return: a list of field names.

        .. versionadded:: 2.3.0
        """

        if self._imageFields is None:
            ctx = SparkContext._active_spark_context
            self._imageFields = list(ctx._jvm.org.apache.spark.ml.image.ImageSchema.imageFields())
        return self._imageFields
Returns field names of image columns.

        :return: a list of field names.

        .. versionadded:: 2.3.0