class_docstr_tok: []
docstr: Adjust Contrast of image.
  
  Contrast is adjusted independently for each channel of each image.
  
  For each channel, this Op computes the mean of the image pixels 
  in the channel and then adjusts each component x of each pixel to 
  (x - mean) * contrast_factor + mean.
  
  Arguments
  ---------
  value : float
      smaller value: less contrast
      ZERO: channel means
      larger positive value: greater contrast
      larger negative value: greater inverse contrast
code: def __init__(self, value):
      """
      Adjust Contrast of image.
  
      Contrast is adjusted independently for each channel of each image.
  
      For each channel, this Op computes the mean of the image pixels
      in the channel and then adjusts each component x of each pixel to
      (x - mean) * contrast_factor + mean.
  
      Arguments
      ---------
      value : float
          smaller value: less contrast
          ZERO: channel means
          larger positive value: greater contrast
          larger negative value: greater inverse contrast
      """
      self.value = value
  
imports: import random
  import torch
  from torchvision.transforms.functional import to_tensor
  import numpy
  from ..utils import th_random_choice
label_desc: Use image node_id 1 to create a new Contrast object  with example: obj = Contrast(value)