'given image index, return preprocessed ground-truth
Parameters
index: int
index of a specific image
Returns
ground-truths of this image'

def label_from_index(self, index):

    assert (self.image_set_index is not None), 'Dataset    not    initialized'
    pos = self.image_set_index[index]
    (n_db, n_index) = self._locate_index(index)
    return self.imdbs[n_db].label_from_index(n_index)
