code: def process_unknown_mask(self, unknown, img_feat, softmax_scale):
      n, _, h, w = img_feat.shape
  
      if unknown is not None:
          unknown = unknown.clone()
          unknown = F.interpolate(
              unknown, scale_factor=1 / self.rate, mode="nearest"
          )
          unknown_mean = unknown.mean(axis=[2, 3])
          known_mean = 1 - unknown_mean
          unknown_scale = paddle.clip(
              paddle.sqrt(unknown_mean / known_mean), 0.1, 10
          )
          known_scale = paddle.clip(
              paddle.sqrt(known_mean / unknown_mean), 0.1, 10
          )
          softmax_scale = paddle.concat(
              [unknown_scale, known_scale], axis=1
          )
      else:
          unknown = paddle.ones([n, 1, h, w])
          softmax_scale = paddle.reshape(
              paddle.to_tensor([softmax_scale, softmax_scale]), (1, 2)
          )
          softmax_scale = paddle.expand(softmax_scale, (n, 2))
  
      return unknown, softmax_scale
  
file_path: PaddleSeg/Matting/ppmatting/models/layers/gca_module.py
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg.cvlibs import param_init
label_desc: Use image node_id 11 for calling the GuidedCxtAtten obj's underlying member method code with example usage: obj.process_unknown_mask(unknown, img_feat, softmax_scale) and returns: unknown,  softmax_scale