uncplx.py

#!/usr/bin/env python

import rasterio as rio
import numpy as np
import sys

with rio.open(sys.argv[1], 'r') as src:
  meta = src.meta
  cplx = src.read(1)

meta.update(
  count=1,
  dtype=np.float64
)

real = cplx.real

with rio.open(sys.argv[2], 'w', **meta) as dst:
  dst.write(1, real)