Clip a FITS image using a different FITS image (e.g. of RMS noise or sensitivity).

clip_image.py

#! /usr/bin/env python

from astropy.io import fits
import numpy as np
from argparse import ArgumentParser

def clip(image, clip_image, clip_level, outname, 
	fill_value=0):
	"""
	"""

	f = fits.open(image)
	g = fits.open(clip_image)

	f[0].data[np.where(g[0].data < clip_level)] = 0

	fits.writeto(outname, f[0].data, f[0].header, clobber=True)


def __main__():
	"""
	"""

	ps = ArgumentParser()
	ps.add_argument("image", help="image to clip")
	ps.add_argument("clip_image", help="image to clip by")
	ps.add_argument("-c", "--clip_level", required=True, type=float, help="clip level")
	ps.add_argument("-o", "--outname", type=str, default="output.fits", help="output file name. This OVERWRITES existing image of the same name.")	
	ps.add_argument("-f", "--fill_value", type=float, help="clipped values replaced with this value")
	ps.add_argument("-F", "--nan_fill_value", action="store_true", help="use NaN instead of fill_value")


	args = ps.parse_args()

	if args.nan_fill_value:
		args.fill_value = np.nan

	clip(image=args.image, 
		 clip_image=clip_image, 
		 clip_level=args.clip_level, 
		 outname=args.outname,
		 fill_value=args.fill_value)


if __name__ == "__main__":
	main()