docstr: Pad image to a specified size.
  Args:
      size (list[int]): image target size
      fill_value (list[float]): rgb value of pad area, default (114.0, 114.0, 114.0)
code: def __init__(self, size, fill_value=[114.0, 114.0, 114.0]):
      """
      Pad image to a specified size.
      Args:
          size (list[int]): image target size
          fill_value (list[float]): rgb value of pad area, default (114.0, 114.0, 114.0)
      """
      super(Pad, self).__init__()
      if isinstance(size, int):
          size = [size, size]
      self.size = size
      self.fill_value = fill_value
  
imports: import base64
  import cv2
  import numpy
  from .keypoint_preprocess import get_affine_transform
label_desc: Use image node_id 1 to create a new Pad object from inherited base classes: object with example: obj = Pad(size, fill_value)