class_docstr: The post process for Differentiable Binarization (DB).
class_docstr_tok: ["The","post","process","for","Differentiable","Binarization","(","DB",")","."]
code: def unclip(self, box, unclip_ratio):
      poly = Polygon(box)
      distance = poly.area * unclip_ratio / poly.length
      offset = pyclipper.PyclipperOffset()
      offset.AddPath(
          box, pyclipper.JT_ROUND, pyclipper.ET_CLOSEDPOLYGON
      )
      expanded = np.array(offset.Execute(distance))
      return expanded
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import cv2
  import paddle
  from shapely.geometry import Polygon
  import pyclipper
label_desc: Use image node_id 4 for calling the DBPostProcess obj's underlying member method code with example usage: obj.unclip(box, unclip_ratio) and returns: expanded