docs: def bounding_box_as_binary_map(alpha, threshold=0.1):
      """
      Similar to `bounding_box`, except returns the bounding box as a
      binary map the same size as the input.
  
      Same parameters as `bounding_box`.
  
      Returns
      -------
      binary_map : ndarray, ndim=2, dtype=np.bool_
          Binary map with True if object and False if background.
      """
  
      bb = bounding_box(alpha)
      x = np.zeros(alpha.shape, dtype=np.bool_)
      x[bb[0]:bb[2], bb[1]:bb[3]] = 1
      return x