code: def preprocess(self, input_dicts, data_id, log_id):
      ((_, input_dict),) = input_dicts.items()
      batch_size = len(input_dict.keys())
      imgs = []
      for key in input_dict.keys():
          data = base64.b64decode(input_dict[key].encode("utf8"))
          byte_stream = io.BytesIO(data)
          img = Image.open(byte_stream)
          img = img.convert("RGB")
          img = self.seq(img)
          imgs.append(img[np.newaxis, :].copy())
      imgs = np.concatenate(imgs, axis=0)
      return {self.input_name: imgs}, False, None, ""
  
imports: import io
  import os
  import sys
  import base64
  import argparse
  import yaml
  import numpy
  from PIL import Image
  from paddle_serving_server.web_service import WebService, Op
  from preprocess_ops import ResizeImage, CenterCropImage, NormalizeImage, ToCHW, Compose
label_desc: Use image node_id 3 for calling the SegOp obj's underlying member method code with example usage: obj.preprocess(input_dicts, data_id, log_id) and returns: dict,  False,  None,  str