def example_reading_spec(self):
    label_key = "image/class/label"
    data_fields, data_items_to_decoders = (
        super(Image2TextProblem, self).example_reading_spec())
    data_fields[label_key] = tf.VarLenFeature(tf.int64)
    data_items_to_decoders["targets"] = contrib.slim().tfexample_decoder.Tensor(
        label_key)
    return data_fields, data_items_to_decoders