code: def channel_angle(im, chanapproxangle=None, *, isshiftdftedge=False,
                    truesize=None):
      
      im = np.asarray(im)
      # Compute edge
      if not isshiftdftedge:
          im = edge(im)
      return reg.orientation_angle(im, isshiftdft=isshiftdftedge,
                                   approxangle=chanapproxangle,
                                   truesize=truesize)
docs: Extract the channel angle from the rfft
  
      Parameters:
      -----------
      im: 2d array
          The channel image
      chanapproxangle: number, optional
          If not None, an approximation of the result
      isshiftdftedge: boolean, default False
          If The image has already been treated:
          (edge, dft, fftshift), set to True
      truesize: 2 numbers, required if isshiftdftedge is True
          The true size of the image
  
      Returns:
      --------
      angle: number
          The channel angle