code: def _l2ycbcr(self, mode):
          
          self._check_modes(("L", "LA"))
  
          luma = self.channels[0]
          zeros = np.ma.zeros(luma.shape)
          zeros.mask = luma.mask
  
          self.channels = [luma, zeros, zeros] + self.channels[1:]
  
          if self.fill_value is not None:
              self.fill_value = [self.fill_value[0], 0, 0] + self.fill_value[1:]
  
          self.mode = mode
docs: Convert from L to YCbCr.