QGIS method to export RAW image into rendered image

renderer.py

def export_as_rendered_image(layer, outfile):
    """Export a QGIS Layer as the rendered image
    
    Usage
    -----
    Use this while working inside QGIS. As of now, I'm not sure
    how to run this outside of QGIS. In addition, files are saved
    in your home directory
    
    ..code-block:: python
      # Get active layer, assuming it's loaded in QGIS already
      layer = iface.activeLayer()
      outfile = 'rendered_image' # No file extension!
    
      export_as_rendered_image(layer, outfile)
      
      # To run on multiple layers, first get a list of layers, and
      # a list of strings for output filenames. Ensure that
      # len(layers) == len(outfiles)
      layers = iface.mapCanvas().layers()
      outfiles = [] # list of output files
      
      for layer, outfile in zip(layers, outfiles):
          export_as_rendered_image(layer, outfile)
      
    
    Parameters
    ----------
    layer : list of qcis._core.QgsRasterLayer
    outfile : list of str
    """
    extent = layer.extent()
    width, height = layer.width(), layer.height()
    renderer = layer.renderer()
    provider=layer.dataProvider()
    crs = layer.crs().toWkt()

    pipe = QgsRasterPipe()
    pipe.set(provider.clone())
    pipe.set(renderer.clone())

    filename = '{}.tif'.format(outfile)
    file_writer = QgsRasterFileWriter(filename)

    file_writer.writeRaster(pipe,
                            width,
                            height,
                            extent,
                            layer.crs())
    print('Exported {}'.format(filename))