code: def remove_alpha(img):
      """Remove the alpha channel from a ``vtk.vtkImageData``.
  
      Parameters
      ----------
      img : vtk.vtkImageData
          The input image data with an alpha channel.
  
      Returns
      -------
      pyvista.ImageData
          The output image data with the alpha channel removed.
  
      """
      ec = _vtk.vtkImageExtractComponents()
      ec.SetComponents(0, 1, 2)
      ec.SetInputData(img)
      ec.Update()
      return pyvista.wrap(ec.GetOutput())
  
file_path: pyvista/pyvista/plotting/utilities/regression.py
imports: from typing import Optional, cast
  import numpy
  import pyvista
  from pyvista.core.utilities.arrays import point_array
  from pyvista.core.utilities.helpers import wrap
  from pyvista.plotting import _vtk
label_desc: Use image node_id 1 for calling a global function with example usage: remove_alpha(img) and returns: pyvista