def orb_labels(orb_number=5):
    """
    Returns the labels (column names) generated by "orb_features".

    Parameters
    ----------
    orb_number : int
        Number of distances that ORB should return.

    Returns
    -------
    labels : array of strings
    """
    return [ "distance_%02d" % i for i in range(orb_number)] + ['distance_mean','distance_std', 'keypoint_count', 'keypoint_hull_area', 'full_keypoint_count']