docstr: Create a new instance of DatasetMeanStdCalculator
  
  Args:
      num_channels: Number of channels in the image. Default value is 3
docstr_tok: ["Create","a","new","instance","of","DatasetMeanStdCalculator","Args",":","num_channels",":","Number","of","channels","in","the","image",".","Default","value","is","3"]
code: def __init__(self, num_channels: int = 3, dtype=np.float64):
      """
      Create a new instance of DatasetMeanStdCalculator
  
      Args:
          num_channels: Number of channels in the image. Default value is 3
      """
      super().__init__()
      self.num_channels = num_channels
      self.global_mean = None
      self.global_var = None
      self.global_max = None
      self.global_min = None
      self.n_items = 0
      self.dtype = dtype
      self.reset()
  
imports: import numpy
  from typing import Optional, Tuple
label_desc: Use image node_id 1 to create a new DatasetMeanStdCalculator object  with example: obj = DatasetMeanStdCalculator(num_channels, dtype)