code: def nonzero_pixels(self):
          
          nonzero_px = np.where(np.sum(self.raw_data, axis=2) > 0)
          nonzero_px = np.c_[nonzero_px[0], nonzero_px[1]]
          return nonzero_px
docs: Return an array of the nonzero pixels.
  
          Returns
          -------
          :obj:`numpy.ndarray`
               Nx2 array of the nonzero pixels