def filter_roidb(roidb, config):
    """ remove roidb entries without usable rois """

    def is_valid(entry):
        """ valid images have at least 1 fg or bg roi """
        overlaps = entry['max_overlaps']
        fg_inds = np.where(overlaps >= config.TRAIN.FG_THRESH)[0]
        bg_inds = np.where((overlaps < config.TRAIN.BG_THRESH_HI) & (overlaps >= config.TRAIN.BG_THRESH_LO))[0]
        valid = len(fg_inds) > 0 or len(bg_inds) > 0
        return valid

    num = len(roidb)
    filtered_roidb = [entry for entry in roidb if is_valid(entry)]
    num_after = len(filtered_roidb)
    print 'filtered %d roidb entries: %d -> %d' % (num - num_after, num, num_after)

    return filtered_roidb
 remove roidb entries without usable rois 
lib/utils/load_data.py