def detect_parent_image_nvr(self, image_name, inspect_data=None):
        """
        Look for the NVR labels, if any, in the image.

        :return NVR string if labels found, otherwise None
        """

        if inspect_data is None:
            inspect_data = self.workflow.builder.parent_image_inspect(image_name)
        labels = Labels(inspect_data[INSPECT_CONFIG].get('Labels', {}))

        label_names = [Labels.LABEL_TYPE_COMPONENT, Labels.LABEL_TYPE_VERSION,
                       Labels.LABEL_TYPE_RELEASE]
        label_values = []

        for lbl_name in label_names:
            try:
                _, lbl_value = labels.get_name_and_value(lbl_name)
                label_values.append(lbl_value)
            except KeyError:
                self.log.info("Failed to find label '%s' in parent image '%s'.",
                              labels.get_name(lbl_name), image_name)

        if len(label_values) != len(label_names):  # don't have all the necessary labels
            self.log.info("Image '%s' NVR missing; not searching for Koji build.", image_name)
            return None

        return '-'.join(label_values)
Look for the NVR labels, if any, in the image.

        :return NVR string if labels found, otherwise None