code: def invert(self):
          
          arr_inv = HeatmapsOnImage.from_0to1(1 - self.arr_0to1, shape=self.shape, min_value=self.min_value,
                                              max_value=self.max_value)
          arr_inv.arr_was_2d = self.arr_was_2d
          return arr_inv
docs: Inverts each value in the heatmap, shifting low towards high values and vice versa.
  
          This changes each value to::
  
              v' = max - (v - min)
  
          where ``v`` is the value at some spatial location, ``min`` is the minimum value in the heatmap
          and ``max`` is the maximum value.
          As the heatmap uses internally a 0.0 to 1.0 representation, this simply becomes ``v' = 1.0 - v``.
  
          Note that the attributes ``min_value`` and ``max_value`` are not switched. They both keep their values.
  
          This function can be useful e.g. when working with depth maps, where algorithms might have
          an easier time representing the furthest away points with zeros, requiring an inverted
          depth map.
  
          Returns
          -------
          arr_inv : imgaug.HeatmapsOnImage
              Inverted heatmap.