'Load HHA features from Gupta et al. ECCV14.
See https://github.com/s-gupta/rcnn-depth/blob/master/rcnn/saveHHA.m'

def load_hha(self, idx):

    im = Image.open('{}/data/hha/img_{}.png'.format(self.nyud_dir, idx))
    hha = np.array(im, dtype=np.float32)
    hha -= self.mean_hha
    hha = hha.transpose((2, 0, 1))
    return hha
