Source code for xrtpy.util.make_exposure_map
import logging
from pathlib import Path
import numpy as np
from astropy.io import fits
from astropy.utils.data import download_file
from xrtpy.util.filename2repo_path import filename2repo_path
__all__ = ["make_exposure_map"]
[docs]
def make_exposure_map(comp_image_file, qualfiles=None, retsatpix=False, verbose=False):
"""
Make an exposure map for a composite image. That is, using data from the
header of a composite image, create an image where the pixel values are
the exposure times used in the composite image
Parameters:
-----------
comp_image_file : string or pathlib.Path object
input composite image. Can be a double or a triple composite
qualfiles : list of strings or Path objects, optional
data quality filenames or paths that correspond to the images that
make up the composite image. If the composite is a triple, should be
list of two values, medium and long. If the composite is a double,
only a single values should be given, the long exposure qualfile.
Must be in order, [medium, long] if composite is a triple.
retsatpix : boolean, optional
if True, return the saturated pixel (boolean) images for the long
image, and if the composite is a triple, also the medium image. If
those images are returned then it is in addtiion to the exposure map,
as a tuple: expmap, lng_sat or expmap, med_sat, lng_sat
verbose : boolean, optional
if True, print diagnostic information
Returns:
--------
exp_map : numpy array
image in the shape of the input composite image where each pixel
has the exposure time that corresponds to that pixel in the composite
image
med_sat : boolean array, optional
if retsatpix is True and the input image is a triple composite, then
this array is returned with the pixels for which the medium exposure
is saturated set to True and all others False
lng_sat : boolean array, optional
if retsatpix is True, then this array is returned with the pixels for
which the long exposure is saturated set to True and all others False
"""
if verbose:
logging.basicConfig(format="%(funcName)s: %(message)s", level=logging.INFO)
comp_header = fits.getheader(comp_image_file)
short_exp_filepath = Path(comp_header["SRTFNAME"])
logging.info(f"short exp. file: {short_exp_filepath}") # noqa: LOG015
short_exp_urlpath = filename2repo_path(short_exp_filepath, join=True)
logging.info(f"short exp. url: {short_exp_urlpath}") # noqa: LOG015
short_exp_filepath = download_file(short_exp_urlpath)
if "MEDFNAME" in comp_header:
triple = True
logging.info("Composite image is a triple") # noqa: LOG015
if qualfiles is None:
medium_exp_filename = Path(comp_header["MEDFNAME"])
medium_exp_qualpath = Path(
medium_exp_filename.stem + ".qual" + medium_exp_filename.suffix
)
medium_exp_urlpath = filename2repo_path(medium_exp_qualpath, join=True)
logging.info(f"medium exp. url: {medium_exp_urlpath}") # noqa: LOG015
medium_exp_qualpath = download_file(medium_exp_urlpath, allow_insecure=True)
else:
medium_exp_qualpath = Path(qualfiles[0])
else:
medium_exp_filename = None
triple = False
logging.info("Composite image is a double") # noqa: LOG015
if qualfiles is None:
long_exp_filename = Path(comp_header["LNGFNAME"])
long_exp_qualpath = Path(
long_exp_filename.stem + ".qual" + long_exp_filename.suffix
)
long_exp_urlpath = filename2repo_path(long_exp_qualpath, join=True)
long_exp_qualpath = download_file(long_exp_urlpath, allow_insecure=True)
else:
if triple:
long_exp_qualpath = Path(qualfiles[1])
else:
long_exp_qualpath = Path(qualfiles)
naxis1 = comp_header["NAXIS1"]
naxis2 = comp_header["NAXIS2"]
srt_exp = fits.getval(short_exp_filepath, "EXPTIME")
logging.info(f"Short image exposure time = {srt_exp}") # noqa: LOG015
lng_hdu = fits.open(long_exp_qualpath)
lng_exp = lng_hdu[0].header["EXPTIME"]
lng_gmap = lng_hdu[0].data
lng_hdu.close()
# do bit arithmetic to get saturated pixels
lng_sat = (lng_gmap & 1).astype(bool)
logging.info(f"No. of saturated pixels in long exposure = {np.sum(lng_sat)}") # noqa: LOG015
exp_map = np.ones((naxis1, naxis2)) * lng_exp
exp_map[lng_sat] = srt_exp
if triple:
med_hdu = fits.open(medium_exp_qualpath)
med_gmap = med_hdu[0].data
med_exp = med_hdu[0].header["EXPTIME"]
med_hdu.close()
med_sat = (med_gmap & 1).astype(bool)
exp_map[~med_sat & lng_sat] = med_exp
logging.info(f"No. of saturated pixels in medium exposure = {np.sum(med_sat)}") # noqa: LOG015
logging.info(f"Medium image exposure time = {med_exp}") # noqa: LOG015
logging.info(f"Long image exposure time = {lng_exp}") # noqa: LOG015
if retsatpix:
if triple:
return exp_map, med_sat, lng_sat
else:
return exp_map, lng_sat
else:
return exp_map
