def background_noise(self):
"""
Gaussian sigma of noise level per pixel in counts (e- or ADU) per second
:return: sqrt(variance) of background noise level in data units
"""
if self._background_noise is None:
if self._read_noise is None:
raise ValueError(
'read_noise is not specified to evaluate background noise!'
)
bkg_noise = data_util.bkg_noise(self._read_noise,
self._exposure_time,
self._sky_brightness_cps,
self.pixel_scale,
num_exposures=self._num_exposures)
if self._data_count_unit == 'ADU':
bkg_noise /= self.ccd_gain
return bkg_noise
else:
if self._read_noise is not None:
warnings.warn(
'read noise is specified but not used for noise properties. background noise is estimated'
' from "background_noise" argument')
return self._background_noise
def background_noise(self):
"""
Gaussian sigma of noise level per pixel (in counts per second)
:return: sqrt(variance) of background noise level
"""
if self._background_noise is None:
return data_util.bkg_noise(self.read_noise,
self._exposure_time,
self.sky_brightness,
self.pixel_scale,
num_exposures=self._num_exposures)
else:
return self._background_noise
def background_noise(self):
"""
Gaussian sigma of noise level per pixel (in counts per second)
:return: sqrt(variance) of background noise level
"""
if self._background_noise is None:
if self._read_noise is None:
raise ValueError('read_noise is not specified to evaluate background noise!')
return data_util.bkg_noise(self.read_noise, self._exposure_time, self.sky_brightness, self.pixel_scale,
num_exposures=self._num_exposures)
else:
if self._read_noise is not None:
warnings.warn('read noise is specified but not used for noise properties. background noise is estimated'
' from "background_noise" argument')
return self._background_noise
def test_bkg_noise():
readout_noise = 2
exposure_time = 100
sky_brightness = 0.01
pixel_scale = 0.05
num_exposures = 10
sigma_bkg = data_util.bkg_noise(readout_noise,
exposure_time,
sky_brightness,
pixel_scale,
num_exposures=num_exposures)
exposure_time_tot = num_exposures * exposure_time
readout_noise_tot = num_exposures * readout_noise**2 # square of readout noise
sky_per_pixel = sky_brightness * pixel_scale**2
sky_brightness_tot = exposure_time_tot * sky_per_pixel
sigma_bkg_ = np.sqrt(readout_noise_tot +
sky_brightness_tot) / exposure_time_tot
npt.assert_almost_equal(sigma_bkg_, sigma_bkg, decimal=8)
def sim_image(self, info_dict):
"""
Simulate an image based on specifications in sim_dict
Args:
info_dict (dict): A single element from the list produced interanlly by input_reader.Organizer.breakup().
Contains all the properties of a single image to generate.
"""
output_image = []
if self.return_planes:
output_source, output_lens, output_point_source, output_noise = [], [], [], []
output_metadata = []
#set the cosmology
cosmology_info = ['H0', 'Om0', 'Tcmb0', 'Neff', 'm_nu', 'Ob0']
cosmo = FlatLambdaCDM(
**dict_select_choose(list(info_dict.values())[0], cosmology_info))
for band, sim_dict in info_dict.items():
# Parse the info dict
params = self.parse_single_band_info_dict(sim_dict,
cosmo,
band=band)
kwargs_single_band = params[0]
kwargs_model = params[1]
kwargs_numerics = params[2]
kwargs_lens_light_list = params[3]
kwargs_source_list = params[4]
kwargs_point_source_list = params[5]
kwargs_lens_model_list = params[6]
output_metadata += params[7]
# Make image
# data properties
kwargs_data = sim_util.data_configure_simple(
sim_dict['numPix'], kwargs_single_band['pixel_scale'],
kwargs_single_band['exposure_time'])
data_class = ImageData(**kwargs_data)
# psf properties
kwargs_psf = {
'psf_type': kwargs_single_band['psf_type'],
'pixel_size': kwargs_single_band['pixel_scale'],
'fwhm': kwargs_single_band['seeing']
}
psf_class = PSF(**kwargs_psf)
# SimAPI instance for conversion to observed quantities
sim = SimAPI(numpix=sim_dict['numPix'],
kwargs_single_band=kwargs_single_band,
kwargs_model=kwargs_model)
kwargs_lens_model_list = sim.physical2lensing_conversion(
kwargs_mass=kwargs_lens_model_list)
kwargs_lens_light_list, kwargs_source_list, _ = sim.magnitude2amplitude(
kwargs_lens_light_mag=kwargs_lens_light_list,
kwargs_source_mag=kwargs_source_list)
# lens model properties
lens_model_class = LensModel(
lens_model_list=kwargs_model['lens_model_list'],
z_lens=kwargs_model['lens_redshift_list'][0],
z_source=kwargs_model['z_source'],
cosmo=cosmo)
# source properties
source_model_class = LightModel(
light_model_list=kwargs_model['source_light_model_list'])
# lens light properties
lens_light_model_class = LightModel(
light_model_list=kwargs_model['lens_light_model_list'])
# solve for PS positions to incorporate time delays
lensEquationSolver = LensEquationSolver(lens_model_class)
kwargs_ps = []
for ps_idx, ps_mag in enumerate(kwargs_point_source_list):
# modify the SimAPI instance to do one point source at a time
temp_kwargs_model = {k: v for k, v in kwargs_model.items()}
temp_kwargs_model['point_source_model_list'] = [
kwargs_model['point_source_model_list'][ps_idx]
]
sim = SimAPI(numpix=sim_dict['numPix'],
kwargs_single_band=kwargs_single_band,
kwargs_model=temp_kwargs_model)
if kwargs_model['point_source_model_list'][
ps_idx] == 'SOURCE_POSITION':
# convert each image to an amplitude
amplitudes = []
for mag in ps_mag['magnitude']:
ps_dict = {k: v for k, v in ps_mag.items()}
ps_dict['magnitude'] = mag
_, _2, ps = sim.magnitude2amplitude(
kwargs_ps_mag=[ps_dict])
amplitudes.append(ps[0]['source_amp'])
x_image, y_image = lensEquationSolver.findBrightImage(
ps[0]['ra_source'],
ps[0]['dec_source'],
kwargs_lens_model_list,
numImages=4, # max number of images
min_distance=kwargs_single_band['pixel_scale'],
search_window=sim_dict['numPix'] *
kwargs_single_band['pixel_scale'])
magnification = lens_model_class.magnification(
x_image, y_image, kwargs=kwargs_lens_model_list)
#amplitudes = np.array(amplitudes) * np.abs(magnification)
amplitudes = np.array(
[a * m for a, m in zip(amplitudes, magnification)])
kwargs_ps.append({
'ra_image': x_image,
'dec_image': y_image,
'point_amp': amplitudes
})
else:
_, _2, ps = sim.magnitude2amplitude(kwargs_ps_mag=[ps_mag])
kwargs_ps.append(ps[0])
# point source properties
point_source_class = PointSource(point_source_type_list=[
x if x != 'SOURCE_POSITION' else 'LENSED_POSITION'
for x in kwargs_model['point_source_model_list']
],
fixed_magnification_list=[False] *
len(kwargs_ps))
# create an image model
image_model = ImageModel(data_class,
psf_class,
lens_model_class,
source_model_class,
lens_light_model_class,
point_source_class,
kwargs_numerics=kwargs_numerics)
# generate image
image_sim = image_model.image(kwargs_lens_model_list,
kwargs_source_list,
kwargs_lens_light_list, kwargs_ps)
poisson = image_util.add_poisson(
image_sim, exp_time=kwargs_single_band['exposure_time'])
sigma_bkg = data_util.bkg_noise(
kwargs_single_band['read_noise'],
kwargs_single_band['exposure_time'],
kwargs_single_band['sky_brightness'],
kwargs_single_band['pixel_scale'],
num_exposures=kwargs_single_band['num_exposures'])
bkg = image_util.add_background(image_sim, sigma_bkd=sigma_bkg)
image = image_sim + bkg + poisson
# Save theta_E (and sigma_v if used)
for ii in range(len(output_metadata)):
output_metadata.append({
'PARAM_NAME':
output_metadata[ii]['PARAM_NAME'].replace(
'sigma_v', 'theta_E'),
'PARAM_VALUE':
kwargs_lens_model_list[output_metadata[ii]
['LENS_MODEL_IDX']]['theta_E'],
'LENS_MODEL_IDX':
output_metadata[ii]['LENS_MODEL_IDX']
})
# Solve lens equation if desired
if self.solve_lens_equation:
#solver = lens_equation_solver.LensEquationSolver(imSim.LensModel)
#x_mins, y_mins = solver.image_position_from_source(sourcePos_x=kwargs_source_list[0]['center_x'],
# sourcePos_y=kwargs_source_list[0]['center_y'],
# kwargs_lens=kwargs_lens_model_list)
x_mins, y_mins = x_image, y_image
num_source_images = len(x_mins)
# Add noise
image_noise = np.zeros(np.shape(image))
for noise_source_num in range(
1, sim_dict['NUMBER_OF_NOISE_SOURCES'] + 1):
image_noise += self._generate_noise(
sim_dict['NOISE_SOURCE_{0}-NAME'.format(noise_source_num)],
np.shape(image),
select_params(
sim_dict,
'NOISE_SOURCE_{0}-'.format(noise_source_num)))
image += image_noise
# Combine with other bands
output_image.append(image)
# Store plane-separated info if requested
if self.return_planes:
output_lens.append(
image_model.lens_surface_brightness(
kwargs_lens_light_list))
output_source.append(
image_model.source_surface_brightness(
kwargs_source_list, kwargs_lens_model_list))
output_point_source.append(
image_model.point_source(kwargs_ps,
kwargs_lens_model_list))
output_noise.append(image_noise)
# Return the desired information in a dictionary
return_dict = {
'output_image': np.array(output_image),
'output_lens_plane': None,
'output_source_plane': None,
'output_point_source_plane': None,
'output_noise_plane': None,
'x_mins': None,
'y_mins': None,
'num_source_images': None,
'additional_metadata': output_metadata
}
if self.return_planes:
return_dict['output_lens_plane'] = np.array(output_lens)
return_dict['output_source_plane'] = np.array(output_source)
return_dict['output_point_source_plane'] = np.array(
output_point_source)
return_dict['output_noise_plane'] = np.array(output_noise)
if self.solve_lens_equation:
return_dict['x_mins'] = x_mins
return_dict['y_mins'] = y_mins
return_dict['num_source_images'] = num_source_images
return return_dict