docs: def get_filter(self, header=None, origin=1):
          """Get filter.
          Often, the regions files implicitly assume the lower-left
          corner of the image as a coordinate (1,1). However, the python
          convetion is that the array index starts from 0. By default
          (``origin=1``), coordinates of the returned mpl artists have
          coordinate shifted by (1, 1). If you do not want this shift,
          use ``origin=0``.
  
          Parameters
          ----------
          header : `astropy.io.fits.Header`
              FITS header
          origin : {0, 1}
              Pixel coordinate origin
  
          Returns
          -------
          filter : TODO
              Filter object
          """
  
          from .region_to_filter import as_region_filter
  
          if header is None:
              if not self.check_imagecoord():
                  raise RuntimeError("the region has non-image coordinate. header is required.")
              reg_in_imagecoord = self
          else:
              reg_in_imagecoord = self.as_imagecoord(header)
  
          region_filter = as_region_filter(reg_in_imagecoord, origin=origin)
  
          return region_filter