code: def __call__(self, im, dpi):
      pad = self.get_pad(dpi)
      padded_src = np.pad(
          im, [(pad, pad), (pad, pad), (0, 0)], "constant"
      )
      tgt_image = self.process_image(padded_src, dpi)
      return tgt_image, -pad, -pad
  
imports: import matplotlib.pyplot
  import numpy
  from matplotlib.artist import Artist
  import matplotlib.cm
  from matplotlib.colors import LightSource
  import matplotlib.transforms
label_desc: Use image node_id 3 for calling the BaseFilter obj's underlying member method code with example usage: obj.__call__(im, dpi) and returns: tgt_image,  unknown,  unknown