def image_gather_channels(image_list: List[Image],
im: Image = None,
subimages=0) -> Image:
"""Gather a list of subimages back into an image using the channel_iterator
If the template image is not given then ti will be formed assuming that the list has
been generated by image_scatter_channels with subimages = number of channels
:param image_list: List of subimages
:param im: Output image
:param subimages: Number of image partitions on each axis (2)
:return: list of subimages
"""
if im is None:
nchan = len(image_list)
_, npol, ny, nx = image_list[0].shape
im_shape = nchan, npol, ny, ny
im = create_image_from_array(
numpy.zeros(im_shape, dtype=image_list[0].data.dtype),
image_list[0].wcs, image_list[0].polarisation_frame)
if subimages == 0:
subimages = len(image_list)
for i, slab in enumerate(image_channel_iter(im, subimages=subimages)):
slab.data[...] = image_list[i].data[...]
return im
def setUp(self):
from data_models.parameters import arl_path
self.dir = arl_path('test_results')
self.niter = 1000
self.lowcore = create_named_configuration('LOWBD2-CORE')
self.nchan = 5
self.times = (numpy.pi / 12.0) * numpy.linspace(-3.0, 3.0, 7)
self.frequency = numpy.linspace(0.9e8, 1.1e8, self.nchan)
self.channel_bandwidth = numpy.array(
self.nchan * [self.frequency[1] - self.frequency[0]])
self.phasecentre = SkyCoord(ra=+0.0 * u.deg,
dec=-45.0 * u.deg,
frame='icrs',
equinox='J2000')
self.vis = create_visibility(
self.lowcore,
self.times,
self.frequency,
self.channel_bandwidth,
phasecentre=self.phasecentre,
weight=1.0,
polarisation_frame=PolarisationFrame('stokesI'),
zerow=True)
self.vis.data['vis'] *= 0.0
# Create model
self.test_model = create_low_test_image_from_gleam(
npixel=512,
cellsize=0.001,
phasecentre=self.vis.phasecentre,
frequency=self.frequency,
channel_bandwidth=self.channel_bandwidth,
flux_limit=1.0)
beam = create_low_test_beam(self.test_model)
export_image_to_fits(beam,
"%s/test_deconvolve_mmclean_beam.fits" % self.dir)
self.test_model.data *= beam.data
export_image_to_fits(
self.test_model,
"%s/test_deconvolve_mmclean_model.fits" % self.dir)
self.vis = predict_2d(self.vis, self.test_model)
assert numpy.max(numpy.abs(self.vis.vis)) > 0.0
self.model = create_image_from_visibility(
self.vis,
npixel=512,
cellsize=0.001,
polarisation_frame=PolarisationFrame('stokesI'))
self.dirty, sumwt = invert_2d(self.vis, self.model)
self.psf, sumwt = invert_2d(self.vis, self.model, dopsf=True)
export_image_to_fits(
self.dirty, "%s/test_deconvolve_mmclean-dirty.fits" % self.dir)
export_image_to_fits(self.psf,
"%s/test_deconvolve_mmclean-psf.fits" % self.dir)
window = numpy.ones(shape=self.model.shape, dtype=numpy.bool)
window[..., 129:384, 129:384] = True
self.innerquarter = create_image_from_array(
window,
self.model.wcs,
polarisation_frame=PolarisationFrame('stokesI'))
def convert_polimage_to_stokes(im: Image):
"""Convert a polarisation image to stokes (complex)
"""
assert isinstance(im, Image)
assert im.data.dtype == 'complex'
if im.polarisation_frame == PolarisationFrame('linear'):
cimarr = convert_linear_to_stokes(im.data)
return create_image_from_array(cimarr, im.wcs,
PolarisationFrame('stokesIQUV'))
elif im.polarisation_frame == PolarisationFrame('circular'):
cimarr = convert_circular_to_stokes(im.data)
return create_image_from_array(cimarr, im.wcs,
PolarisationFrame('stokesIQUV'))
else:
raise ValueError("Cannot convert %s to stokes" %
(im.polarisation_frame.type))
def convert_stokes_to_polimage(im: Image,
polarisation_frame: PolarisationFrame):
"""Convert a stokes image to polarisation_frame
"""
assert isinstance(im, Image)
assert isinstance(polarisation_frame, PolarisationFrame)
if polarisation_frame == PolarisationFrame('linear'):
cimarr = convert_stokes_to_linear(im.data)
return create_image_from_array(cimarr, im.wcs, polarisation_frame)
elif polarisation_frame == PolarisationFrame('circular'):
cimarr = convert_stokes_to_circular(im.data)
return create_image_from_array(cimarr, im.wcs, polarisation_frame)
else:
raise ValueError("Cannot convert stokes to %s" %
(polarisation_frame.type))
def create_low_test_beam(model: Image) -> Image:
"""Create a test power beam for LOW using an image from OSKAR
:param model: Template image
:return: Image
"""
beam = import_image_from_fits(arl_path('data/models/SKA1_LOW_beam.fits'))
# Scale the image cellsize to account for the different in frequencies. Eventually we will want to
# use a frequency cube
log.info("create_low_test_beam: primary beam is defined at %.3f MHz" %
(beam.wcs.wcs.crval[2] * 1e-6))
nchan, npol, ny, nx = model.shape
# We need to interpolate each frequency channel separately. The beam is assumed to just scale with
# frequency.
reprojected_beam = create_empty_image_like(model)
for chan in range(nchan):
model2dwcs = model.wcs.sub(2).deepcopy()
model2dshape = [model.shape[2], model.shape[3]]
beam2dwcs = beam.wcs.sub(2).deepcopy()
# The frequency axis is the second to last in the beam
frequency = model.wcs.sub(['spectral']).wcs_pix2world([chan], 0)[0]
fscale = beam.wcs.wcs.crval[2] / frequency
beam2dwcs.wcs.cdelt = fscale * beam.wcs.sub(2).wcs.cdelt
beam2dwcs.wcs.crpix = beam.wcs.sub(2).wcs.crpix
beam2dwcs.wcs.crval = model.wcs.sub(2).wcs.crval
beam2dwcs.wcs.ctype = model.wcs.sub(2).wcs.ctype
model2dwcs.wcs.crpix = [
model.shape[2] // 2 + 1, model.shape[3] // 2 + 1
]
beam2d = create_image_from_array(beam.data[0, 0, :, :], beam2dwcs,
model.polarisation_frame)
reprojected_beam2d, footprint = reproject_image(beam2d,
model2dwcs,
shape=model2dshape)
assert numpy.max(
footprint.data) > 0.0, "No overlap between beam and model"
reprojected_beam2d.data *= reprojected_beam2d.data
reprojected_beam2d.data[footprint.data <= 0.0] = 0.0
for pol in range(npol):
reprojected_beam.data[chan,
pol, :, :] = reprojected_beam2d.data[:, :]
return reprojected_beam
def calculate_image_frequency_moments(im: Image,
reference_frequency=None,
nmoments=3) -> Image:
"""Calculate frequency weighted moments
Weights are ((freq-reference_frequency)/reference_frequency)**moment
Note that the spectral axis is replaced by a MOMENT axis.
For example, to find the moments and then reconstruct from just the moments::
moment_cube = calculate_image_frequency_moments(model_multichannel, nmoments=5)
reconstructed_cube = calculate_image_from_frequency_moments(model_multichannel, moment_cube)
:param im: Image cube
:param reference_frequency: Reference frequency (default None uses average)
:param nmoments: Number of moments to calculate
:return: Moments image
"""
assert isinstance(im, Image)
nchan, npol, ny, nx = im.shape
channels = numpy.arange(nchan)
with warnings.catch_warnings():
warnings.simplefilter('ignore', FITSFixedWarning)
freq = im.wcs.sub(['spectral']).wcs_pix2world(channels, 0)[0]
assert nmoments <= nchan, "Number of moments %d cannot exceed the number of channels %d" % (
nmoments, nchan)
if reference_frequency is None:
reference_frequency = numpy.average(freq)
log.debug(
"calculate_image_frequency_moments: Reference frequency = %.3f (MHz)" %
(reference_frequency / 1e6))
moment_data = numpy.zeros([nmoments, npol, ny, nx])
for moment in range(nmoments):
for chan in range(nchan):
weight = numpy.power(
(freq[chan] - reference_frequency) / reference_frequency,
moment)
moment_data[moment, ...] += im.data[chan, ...] * weight
moment_wcs = copy.deepcopy(im.wcs)
moment_wcs.wcs.ctype[3] = 'MOMENT'
moment_wcs.wcs.crval[3] = 0.0
moment_wcs.wcs.crpix[3] = 1.0
moment_wcs.wcs.cdelt[3] = 1.0
moment_wcs.wcs.cunit[3] = ''
return create_image_from_array(moment_data, moment_wcs,
im.polarisation_frame)
def test_create_image_from_array(self):
m31model_by_array = create_image_from_array(
self.m31image.data, self.m31image.wcs,
self.m31image.polarisation_frame)
add_image(self.m31image, m31model_by_array)
add_image(self.m31image, m31model_by_array, docheckwcs=True)
assert m31model_by_array.shape == self.m31image.shape
log.debug(
export_image_to_fits(self.m31image,
fitsfile='%s/test_model.fits' % (self.dir)))
log.debug(qa_image(m31model_by_array,
context='test_create_from_image'))
def reproject_image(im: Image, newwcs: WCS, shape=None) -> (Image, Image):
""" Re-project an image to a new coordinate system
Currently uses the reproject python package. This seems to have some features do be careful using this method.
For timeslice imaging I had to use griddata.
:param im: Image to be reprojected
:param newwcs: New WCS
:param shape:
:return: Reprojected Image, Footprint Image
"""
assert isinstance(im, Image), im
rep, foot = reproject_interp((im.data, im.wcs),
newwcs,
shape,
order='bicubic',
independent_celestial_slices=True)
return create_image_from_array(
rep, newwcs, im.polarisation_frame), create_image_from_array(
foot, newwcs, im.polarisation_frame)
def convert_hdf_to_image(f):
""" Convert HDF root to an Image
:param f:
:return:
"""
assert f.attrs['ARL_data_model'] == "Image", "Not an Image"
data = numpy.array(f['data'])
polarisation_frame = PolarisationFrame(f.attrs['polarisation_frame'])
wcs = WCS(f.attrs['wcs'])
im = create_image_from_array(data, wcs=wcs,
polarisation_frame=polarisation_frame)
return im
def add_image(im1: Image, im2: Image, docheckwcs=False) -> Image:
""" Add two images
:param docheckwcs:
:param im1:
:param im2:
:return: Image
"""
assert isinstance(im1, Image), im1
assert isinstance(im2, Image), im2
if docheckwcs:
checkwcs(im1.wcs, im2.wcs)
assert im1.polarisation_frame == im2.polarisation_frame
return create_image_from_array(im1.data + im2.data, im1.wcs,
im1.polarisation_frame)
def setUp(self):
from data_models.parameters import arl_path
self.dir = arl_path('test_results')
self.lowcore = create_named_configuration('LOWBD2-CORE')
self.times = (numpy.pi / (12.0)) * numpy.linspace(-3.0, 3.0, 7)
self.frequency = numpy.array([1e8])
self.channel_bandwidth = numpy.array([1e6])
self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
dec=-60.0 * u.deg,
frame='icrs',
equinox='J2000')
self.vis = create_visibility(
self.lowcore,
self.times,
self.frequency,
channel_bandwidth=self.channel_bandwidth,
phasecentre=self.phasecentre,
weight=1.0,
polarisation_frame=PolarisationFrame('stokesI'),
zerow=True)
self.vis.data['vis'] *= 0.0
# Create model
self.test_model = create_test_image(cellsize=0.001,
phasecentre=self.vis.phasecentre,
frequency=self.frequency)
self.vis = predict_2d(self.vis, self.test_model)
assert numpy.max(numpy.abs(self.vis.vis)) > 0.0
self.model = create_image_from_visibility(
self.vis,
npixel=512,
cellsize=0.001,
polarisation_frame=PolarisationFrame('stokesI'))
self.dirty, sumwt = invert_2d(self.vis, self.model)
self.psf, sumwt = invert_2d(self.vis, self.model, dopsf=True)
window = numpy.zeros(shape=self.model.shape, dtype=numpy.bool)
window[..., 129:384, 129:384] = True
self.innerquarter = create_image_from_array(
window,
self.model.wcs,
polarisation_frame=PolarisationFrame('stokesI'))
def image_channel_iter(im: Image, subimages=1) -> collections.Iterable:
"""Create a image_channel_iter generator, returning images
The WCS is adjusted appropriately for each raster element. Hence this is a coordinate-aware
way to iterate through an image.
Provided we don't break reference semantics, memory should be conserved
To update the image in place:
for r in raster(im, facets=2)::
r.data[...] = numpy.sqrt(r.data[...])
:param im: Image
:param subimages: Number of subimages
"""
nchan, npol, ny, nx = im.shape
assert subimages <= nchan, "More subimages %d than channels %d" % (
subimages, nchan)
step = nchan // subimages
channels = numpy.array(range(0, nchan, step), dtype='int')
assert len(
channels
) == subimages, "subimages %d does not match length of channels %d" % (
subimages, len(channels))
for i, channel in enumerate(channels):
if i + 1 < len(channels):
channel_max = channels[i + 1]
else:
channel_max = nchan
# Adjust WCS
wcs = im.wcs.deepcopy()
wcs.wcs.crpix[3] -= channel
# Yield image from slice (reference!)
yield create_image_from_array(im.data[channel:channel_max, ...], wcs,
im.polarisation_frame)
def create_low_test_image_from_gleam(npixel=512,
polarisation_frame=PolarisationFrame(
"stokesI"),
cellsize=0.000015,
frequency=numpy.array([1e8]),
channel_bandwidth=numpy.array([1e6]),
phasecentre=None,
kind='cubic',
applybeam=False,
flux_limit=0.1,
radius=None,
insert_method='Nearest') -> Image:
"""Create LOW test image from the GLEAM survey
Stokes I is estimated from a cubic spline fit to the measured fluxes. The polarised flux is always zero.
See http://www.mwatelescope.org/science/gleam-survey The catalog is available from Vizier.
VIII/100 GaLactic and Extragalactic All-sky MWA survey (Hurley-Walker+, 2016)
GaLactic and Extragalactic All-sky Murchison Wide Field Array (GLEAM) survey. I: A low-frequency extragalactic
catalogue. Hurley-Walker N., et al., Mon. Not. R. Astron. Soc., 464, 1146-1167 (2017), 2017MNRAS.464.1146H
:param npixel: Number of pixels
:param polarisation_frame: Polarisation frame (default PolarisationFrame("stokesI"))
:param cellsize: cellsize in radians
:param frequency:
:param channel_bandwidth: Channel width (Hz)
:param phasecentre: phasecentre (SkyCoord)
:param kind: Kind of interpolation (see scipy.interpolate.interp1d) Default: linear
:return: Image
"""
if phasecentre is None:
phasecentre = SkyCoord(ra=+15.0 * u.deg,
dec=-35.0 * u.deg,
frame='icrs',
equinox='J2000')
if radius is None:
radius = npixel * cellsize / numpy.sqrt(2.0)
sc = create_low_test_skycomponents_from_gleam(
flux_limit=flux_limit,
polarisation_frame=polarisation_frame,
frequency=frequency,
phasecentre=phasecentre,
kind=kind,
radius=radius)
if polarisation_frame is None:
polarisation_frame = PolarisationFrame("stokesI")
npol = polarisation_frame.npol
nchan = len(frequency)
shape = [nchan, npol, npixel, npixel]
w = WCS(naxis=4)
# The negation in the longitude is needed by definition of RA, DEC
w.wcs.cdelt = [
-cellsize * 180.0 / numpy.pi, cellsize * 180.0 / numpy.pi, 1.0,
channel_bandwidth[0]
]
w.wcs.crpix = [npixel // 2 + 1, npixel // 2 + 1, 1.0, 1.0]
w.wcs.ctype = ["RA---SIN", "DEC--SIN", 'STOKES', 'FREQ']
w.wcs.crval = [phasecentre.ra.deg, phasecentre.dec.deg, 1.0, frequency[0]]
w.naxis = 4
w.wcs.radesys = 'ICRS'
w.wcs.equinox = 2000.0
model = create_image_from_array(numpy.zeros(shape),
w,
polarisation_frame=polarisation_frame)
model = insert_skycomponent(model, sc, insert_method=insert_method)
if applybeam:
beam = create_low_test_beam(model)
model.data[...] *= beam.data[...]
log.info(qa_image(model, context='create_low_test_image_from_gleam'))
return model
def create_image_from_visibility(vis, **kwargs) -> Image:
"""Make an empty image from params and Visibility
:param vis:
:param phasecentre: Phasecentre (Skycoord)
:param channel_bandwidth: Channel width (Hz)
:param cellsize: Cellsize (radians)
:param npixel: Number of pixels on each axis (512)
:param frame: Coordinate frame for WCS (ICRS)
:param equinox: Equinox for WCS (2000.0)
:param nchan: Number of image channels (Default is 1 -> MFS)
:return: image
"""
assert isinstance(vis, Visibility) or isinstance(vis, BlockVisibility), \
"vis is not a Visibility or a BlockVisibility: %r" % (vis)
log.info(
"create_image_from_visibility: Parsing parameters to get definition of WCS"
)
imagecentre = get_parameter(kwargs, "imagecentre", vis.phasecentre)
phasecentre = get_parameter(kwargs, "phasecentre", vis.phasecentre)
# Spectral processing options
ufrequency = numpy.unique(vis.frequency)
vnchan = len(ufrequency)
frequency = get_parameter(kwargs, "frequency", vis.frequency)
inchan = get_parameter(kwargs, "nchan", vnchan)
reffrequency = frequency[0] * units.Hz
channel_bandwidth = get_parameter(
kwargs, "channel_bandwidth",
0.99999999999 * vis.channel_bandwidth[0]) * units.Hz
if (inchan == vnchan) and vnchan > 1:
log.info(
"create_image_from_visibility: Defining %d channel Image at %s, starting frequency %s, and bandwidth %s"
% (inchan, imagecentre, reffrequency, channel_bandwidth))
elif (inchan == 1) and vnchan > 1:
assert numpy.abs(channel_bandwidth.value
) > 0.0, "Channel width must be non-zero for mfs mode"
log.info(
"create_image_from_visibility: Defining single channel MFS Image at %s, starting frequency %s, "
"and bandwidth %s" %
(imagecentre, reffrequency, channel_bandwidth))
elif inchan > 1 and vnchan > 1:
assert numpy.abs(channel_bandwidth.value
) > 0.0, "Channel width must be non-zero for mfs mode"
log.info(
"create_image_from_visibility: Defining multi-channel MFS Image at %s, starting frequency %s, "
"and bandwidth %s" %
(imagecentre, reffrequency, channel_bandwidth))
elif (inchan == 1) and (vnchan == 1):
assert numpy.abs(channel_bandwidth.value
) > 0.0, "Channel width must be non-zero for mfs mode"
log.info(
"create_image_from_visibility: Defining single channel Image at %s, starting frequency %s, "
"and bandwidth %s" %
(imagecentre, reffrequency, channel_bandwidth))
else:
raise ValueError(
"create_image_from_visibility: unknown spectral mode ")
# Image sampling options
npixel = get_parameter(kwargs, "npixel", 512)
uvmax = numpy.max((numpy.abs(vis.data['uvw'][:, 0:1])))
if isinstance(vis, BlockVisibility):
uvmax *= numpy.max(frequency) / constants.c.to('m s^-1').value
log.info("create_image_from_visibility: uvmax = %f wavelengths" % uvmax)
criticalcellsize = 1.0 / (uvmax * 2.0)
log.info(
"create_image_from_visibility: Critical cellsize = %f radians, %f degrees"
% (criticalcellsize, criticalcellsize * 180.0 / numpy.pi))
cellsize = get_parameter(kwargs, "cellsize", 0.5 * criticalcellsize)
log.info(
"create_image_from_visibility: Cellsize = %f radians, %f degrees"
% (cellsize, cellsize * 180.0 / numpy.pi))
override_cellsize = get_parameter(kwargs, "override_cellsize", True)
if override_cellsize and cellsize > criticalcellsize:
log.info(
"create_image_from_visibility: Resetting cellsize %f radians to criticalcellsize %f radians"
% (cellsize, criticalcellsize))
cellsize = criticalcellsize
pol_frame = get_parameter(kwargs, "polarisation_frame",
PolarisationFrame("stokesI"))
inpol = pol_frame.npol
# Now we can define the WCS, which is a convenient place to hold the info above
# Beware of python indexing order! wcs and the array have opposite ordering
shape = [inchan, inpol, npixel, npixel]
w = wcs.WCS(naxis=4)
# The negation in the longitude is needed by definition of RA, DEC
w.wcs.cdelt = [
-cellsize * 180.0 / numpy.pi, cellsize * 180.0 / numpy.pi, 1.0,
channel_bandwidth.to(units.Hz).value
]
# The numpy definition of the phase centre of an FFT is n // 2 (0 - rel) so that's what we use for
# the reference pixel. We have to use 0 rel everywhere.
w.wcs.crpix = [npixel // 2 + 1, npixel // 2 + 1, 1.0, 1.0]
w.wcs.ctype = ["RA---SIN", "DEC--SIN", 'STOKES', 'FREQ']
w.wcs.crval = [
phasecentre.ra.deg, phasecentre.dec.deg, 1.0,
reffrequency.to(units.Hz).value
]
w.naxis = 4
direction_centre = pixel_to_skycoord(npixel // 2 + 1,
npixel // 2 + 1,
wcs=w,
origin=1)
assert direction_centre.separation(imagecentre).value < 1e-7, \
"Image phase centre [npixel//2, npixel//2] should be %s, actually is %s" % \
(str(imagecentre), str(direction_centre))
w.wcs.radesys = get_parameter(kwargs, 'frame', 'ICRS')
w.wcs.equinox = get_parameter(kwargs, 'equinox', 2000.0)
return create_image_from_array(numpy.zeros(shape),
wcs=w,
polarisation_frame=pol_frame)
def invert_2d(vis: Visibility, im: Image, dopsf: bool = False, normalize: bool = True, **kwargs) \
-> (Image, numpy.ndarray):
""" Invert using 2D convolution function, including w projection optionally
Use the image im as a template. Do PSF in a separate call.
This is at the bottom of the layering i.e. all transforms are eventually expressed in terms
of this function. . Any shifting needed is performed here.
:param vis: Visibility to be inverted
:param im: image template (not changed)
:param dopsf: Make the psf instead of the dirty image
:param normalize: Normalize by the sum of weights (True)
:return: resulting image
"""
if not isinstance(vis, Visibility):
svis = coalesce_visibility(vis, **kwargs)
else:
svis = copy_visibility(vis)
if dopsf:
svis.data['vis'] = numpy.ones_like(svis.data['vis'])
svis = shift_vis_to_image(svis, im, tangent=True, inverse=False)
nchan, npol, ny, nx = im.data.shape
padding = {}
if get_parameter(kwargs, "padding", False):
padding = {'padding': get_parameter(kwargs, "padding", False)}
spectral_mode, vfrequencymap = get_frequency_map(svis, im)
polarisation_mode, vpolarisationmap = get_polarisation_map(svis, im)
uvw_mode, shape, padding, vuvwmap = get_uvw_map(svis, im, **padding)
kernel_name, gcf, vkernellist = get_kernel_list(svis, im, **kwargs)
# Optionally pad to control aliasing
imgridpad = numpy.zeros(
[nchan, npol,
int(round(padding * ny)),
int(round(padding * nx))],
dtype='complex')
imgridpad, sumwt = convolutional_grid(vkernellist, imgridpad,
svis.data['vis'],
svis.data['imaging_weight'], vuvwmap,
vfrequencymap)
# Fourier transform the padded grid to image, multiply by the gridding correction
# function, and extract the unpadded inner part.
# Normalise weights for consistency with transform
sumwt /= float(padding * int(round(padding * nx)) * ny)
imaginary = get_parameter(kwargs, "imaginary", False)
if imaginary:
log.debug("invert_2d: retaining imaginary part of dirty image")
result = extract_mid(ifft(imgridpad) * gcf, npixel=nx)
resultreal = create_image_from_array(result.real, im.wcs,
im.polarisation_frame)
resultimag = create_image_from_array(result.imag, im.wcs,
im.polarisation_frame)
if normalize:
resultreal = normalize_sumwt(resultreal, sumwt)
resultimag = normalize_sumwt(resultimag, sumwt)
return resultreal, sumwt, resultimag
else:
result = extract_mid(numpy.real(ifft(imgridpad)) * gcf, npixel=nx)
resultimage = create_image_from_array(result, im.wcs,
im.polarisation_frame)
if normalize:
resultimage = normalize_sumwt(resultimage, sumwt)
return resultimage, sumwt
def image_raster_iter(im: Image,
facets=1,
overlap=0,
taper='flat',
make_flat=False) -> collections.Iterable:
"""Create an image_raster_iter generator, returning images, optionally with overlaps
The WCS is adjusted appropriately for each raster element. Hence this is a coordinate-aware
way to iterate through an image.
Provided we don't break reference semantics, memory should be conserved. However make_flat
creates a new set of images and thus reference semantics dont hold.
To update the image in place:
for r in raster(im, facets=2)::
r.data[...] = numpy.sqrt(r.data[...])
If the overlap is greater than zero, we choose to keep all images the same size so the
other ring of facets are ignored. So if facets=4 and overlap > 0 then the iterator returns
(facets-2)**2 = 4 images.
A taper is applied in the overlap regions. None implies a constant value, linear is a ramp, and
quadratic is parabolic at the ends.
:param im: Image
:param facets: Number of image partitions on each axis (2)
:param overlap: overlap in pixels
:param taper: method of tapering at the edges: 'flat' or 'linear' or 'quadratic' or 'tukey'
:param make_flat: Make the flat images
"""
nchan, npol, ny, nx = im.shape
log.debug("image_raster_iter: predicting using %d x %d image partitions" %
(facets, facets))
assert facets <= ny, "Cannot have more raster elements than pixels"
assert facets <= nx, "Cannot have more raster elements than pixels"
if facets == 1 and overlap == 0:
yield im
else:
assert overlap < (nx // facets), "Overlap in facets is too large"
assert overlap < (ny // facets), "Overlap in facets is too large"
# Step between facets
sx = nx // facets + overlap
sy = ny // facets + overlap
# Size of facet
dx = sx + overlap
dy = sy + overlap
# Step between facets
sx = nx // facets + overlap
sy = ny // facets + overlap
# Size of facet
dx = nx // facets + 2 * overlap
dy = nx // facets + 2 * overlap
def taper_linear():
t = numpy.ones(dx)
ramp = numpy.arange(0, overlap).astype(float) / float(overlap)
t[:overlap] = ramp
t[(dx - overlap):dx] = 1.0 - ramp
result = numpy.outer(t, t)
return result
def taper_quadratic():
t = numpy.ones(dx)
ramp = numpy.arange(0, overlap).astype(float) / float(overlap)
quadratic_ramp = numpy.ones(overlap)
quadratic_ramp[0:overlap // 2] = 2.0 * ramp[0:overlap // 2]**2
quadratic_ramp[overlap //
2:] = 1 - 2.0 * ramp[overlap // 2:0:-1]**2
t[:overlap] = quadratic_ramp
t[(dx - overlap):dx] = 1.0 - quadratic_ramp
result = numpy.outer(t, t)
return result
def taper_tukey():
xs = numpy.arange(dx) / float(dx)
r = 2 * overlap / dx
t = [tukey_filter(x, r) for x in xs]
result = numpy.outer(t, t)
return result
log.debug('image_raster_iter: spacing of raster (%d, %d)' % (dx, dy))
i = 0
for fy in range(facets):
y = ny // 2 + sy * (fy - facets // 2) - overlap // 2
for fx in range(facets):
x = nx // 2 + sx * (fx - facets // 2) - overlap // 2
if (x >= 0) and (x + dx) <= nx and (y >= 0) and (y + dy) <= ny:
log.debug(
'image_raster_iter: partition (%d, %d) of (%d, %d)' %
(fy, fx, facets, facets))
# Adjust WCS
wcs = im.wcs.deepcopy()
wcs.wcs.crpix[0] -= x
wcs.wcs.crpix[1] -= y
# yield image from slice (reference!)
subim = create_image_from_array(
im.data[..., y:y + dy, x:x + dx], wcs,
im.polarisation_frame)
if overlap > 0 and make_flat:
flat = create_empty_image_like(subim)
if taper == 'linear':
flat.data[..., :, :] = taper_linear()
elif taper == 'quadratic':
flat.data[..., :, :] = taper_quadratic()
elif taper == 'tukey':
flat.data[..., :, :] = taper_tukey()
else:
flat.data[...] = 1.0
yield flat
else:
yield subim
i += 1
def deconvolve_cube(dirty: Image,
psf: Image,
prefix='',
**kwargs) -> (Image, Image):
""" Clean using a variety of algorithms
Functions that clean a dirty image using a point spread function. The algorithms available are:
hogbom: Hogbom CLEAN See: Hogbom CLEAN A&A Suppl, 15, 417, (1974)
msclean: MultiScale CLEAN See: Cornwell, T.J., Multiscale CLEAN (IEEE Journal of Selected Topics in Sig Proc,
2008 vol. 2 pp. 793-801)
mfsmsclean, msmfsclean, mmclean: MultiScale Multi-Frequency See: U. Rau and T. J. Cornwell,
“A multi-scale multi-frequency deconvolution algorithm for synthesis imaging in radio interferometry,” A&A 532,
A71 (2011).
For example::
comp, residual = deconvolve_cube(dirty, psf, niter=1000, gain=0.7, algorithm='msclean',
scales=[0, 3, 10, 30], threshold=0.01)
For the MFS clean, the psf must have number of channels >= 2 * nmoments
:param dirty: Image dirty image
:param psf: Image Point Spread Function
:param window: Window image (Bool) - clean where True
:param algorithm: Cleaning algorithm: 'msclean'|'hogbom'|'mfsmsclean'
:param gain: loop gain (float) 0.7
:param threshold: Clean threshold (0.0)
:param fractional_threshold: Fractional threshold (0.01)
:param scales: Scales (in pixels) for multiscale ([0, 3, 10, 30])
:param nmoments: Number of frequency moments (default 3)
:param findpeak: Method of finding peak in mfsclean: 'Algorithm1'|'ASKAPSoft'|'CASA'|'ARL', Default is ARL.
:return: componentimage, residual
"""
assert isinstance(dirty, Image), dirty
assert isinstance(psf, Image), psf
window_shape = get_parameter(kwargs, 'window_shape', None)
if window_shape == 'quarter':
qx = dirty.shape[3] // 4
qy = dirty.shape[2] // 4
window = numpy.zeros_like(dirty.data)
window[..., (qy + 1):3 * qy, (qx + 1):3 * qx] = 1.0
log.info(
'deconvolve_cube %s: Cleaning inner quarter of each sky plane' %
prefix)
else:
window = None
psf_support = get_parameter(kwargs, 'psf_support',
max(dirty.shape[2] // 2, dirty.shape[3] // 2))
if (psf_support <= psf.shape[2] // 2) and (
(psf_support <= psf.shape[3] // 2)):
centre = [psf.shape[2] // 2, psf.shape[3] // 2]
psf.data = psf.data[..., (centre[0] - psf_support):(centre[0] +
psf_support),
(centre[1] - psf_support):(centre[1] +
psf_support)]
log.info('deconvolve_cube %s: PSF support = +/- %d pixels' %
(prefix, psf_support))
log.info('deconvolve_cube %s: PSF shape %s' %
(prefix, str(psf.data.shape)))
algorithm = get_parameter(kwargs, 'algorithm', 'msclean')
if algorithm == 'msclean':
log.info(
"deconvolve_cube %s: Multi-scale clean of each polarisation and channel separately"
% prefix)
gain = get_parameter(kwargs, 'gain', 0.7)
assert 0.0 < gain < 2.0, "Loop gain must be between 0 and 2"
thresh = get_parameter(kwargs, 'threshold', 0.0)
assert thresh >= 0.0
niter = get_parameter(kwargs, 'niter', 100)
assert niter > 0
scales = get_parameter(kwargs, 'scales', [0, 3, 10, 30])
fracthresh = get_parameter(kwargs, 'fractional_threshold', 0.01)
assert 0.0 < fracthresh < 1.0
comp_array = numpy.zeros_like(dirty.data)
residual_array = numpy.zeros_like(dirty.data)
for channel in range(dirty.data.shape[0]):
for pol in range(dirty.data.shape[1]):
if psf.data[channel, pol, :, :].max():
log.info(
"deconvolve_cube %s: Processing pol %d, channel %d" %
(prefix, pol, channel))
if window is None:
comp_array[channel, pol, :, :], residual_array[channel, pol, :, :] = \
msclean(dirty.data[channel, pol, :, :], psf.data[channel, pol, :, :],
None, gain, thresh, niter, scales, fracthresh, prefix)
else:
comp_array[channel, pol, :, :], residual_array[channel, pol, :, :] = \
msclean(dirty.data[channel, pol, :, :], psf.data[channel, pol, :, :],
window[channel, pol, :, :], gain, thresh, niter, scales, fracthresh,
prefix)
else:
log.info(
"deconvolve_cube %s: Skipping pol %d, channel %d" %
(prefix, pol, channel))
comp_image = create_image_from_array(comp_array, dirty.wcs,
dirty.polarisation_frame)
residual_image = create_image_from_array(residual_array, dirty.wcs,
dirty.polarisation_frame)
elif algorithm == 'msmfsclean' or algorithm == 'mfsmsclean' or algorithm == 'mmclean':
findpeak = get_parameter(kwargs, "findpeak", 'ARL')
log.info(
"deconvolve_cube %s: Multi-scale multi-frequency clean of each polarisation separately"
% prefix)
nmoments = get_parameter(kwargs, "nmoments", 3)
assert nmoments > 0, "Number of frequency moments must be greater than zero"
nchan = dirty.shape[0]
assert nchan > 2 * nmoments, "Require nchan %d > 2 * nmoments %d" % (
nchan, 2 * nmoments)
dirty_taylor = calculate_image_frequency_moments(dirty,
nmoments=nmoments)
psf_taylor = calculate_image_frequency_moments(psf,
nmoments=2 * nmoments)
psf_peak = numpy.max(psf_taylor.data)
dirty_taylor.data /= psf_peak
psf_taylor.data /= psf_peak
log.info("deconvolve_cube %s: Shape of Dirty moments image %s" %
(prefix, str(dirty_taylor.shape)))
log.info("deconvolve_cube %s: Shape of PSF moments image %s" %
(prefix, str(psf_taylor.shape)))
gain = get_parameter(kwargs, 'gain', 0.7)
assert 0.0 < gain < 2.0, "Loop gain must be between 0 and 2"
thresh = get_parameter(kwargs, 'threshold', 0.0)
assert thresh >= 0.0
niter = get_parameter(kwargs, 'niter', 100)
assert niter > 0
scales = get_parameter(kwargs, 'scales', [0, 3, 10, 30])
fracthresh = get_parameter(kwargs, 'fractional_threshold', 0.1)
assert 0.0 < fracthresh < 1.0
comp_array = numpy.zeros(dirty_taylor.data.shape)
residual_array = numpy.zeros(dirty_taylor.data.shape)
for pol in range(dirty_taylor.data.shape[1]):
if psf_taylor.data[0, pol, :, :].max():
log.info("deconvolve_cube %s: Processing pol %d" %
(prefix, pol))
if window is None:
comp_array[:, pol, :, :], residual_array[:, pol, :, :] = \
msmfsclean(dirty_taylor.data[:, pol, :, :], psf_taylor.data[:, pol, :, :],
None, gain, thresh, niter, scales, fracthresh, findpeak, prefix)
else:
qx = dirty.shape[3] // 4
qy = dirty.shape[2] // 4
window_taylor = numpy.zeros_like(dirty_taylor.data)
window_taylor[..., (qy + 1):3 * qy, (qx + 1):3 * qx] = 1.0
log.info(
'deconvolve_cube %s: Cleaning inner quarter of each moment plane'
% prefix)
comp_array[:, pol, :, :], residual_array[:, pol, :, :] = \
msmfsclean(dirty_taylor.data[:, pol, :, :], psf_taylor.data[:, pol, :, :],
window_taylor[0, pol, :, :], gain, thresh, niter, scales, fracthresh,
findpeak, prefix)
else:
log.info("deconvolve_cube %s: Skipping pol %d" % (prefix, pol))
comp_image = create_image_from_array(comp_array, dirty_taylor.wcs,
dirty.polarisation_frame)
residual_image = create_image_from_array(residual_array,
dirty_taylor.wcs,
dirty.polarisation_frame)
return_moments = get_parameter(kwargs, "return_moments", False)
if not return_moments:
log.info("deconvolve_cube %s: calculating spectral cubes" % prefix)
comp_image = calculate_image_from_frequency_moments(
dirty, comp_image)
residual_image = calculate_image_from_frequency_moments(
dirty, residual_image)
else:
log.info("deconvolve_cube %s: constructed moment cubes" % prefix)
elif algorithm == 'hogbom':
log.info(
"deconvolve_cube %s: Hogbom clean of each polarisation and channel separately"
% prefix)
gain = get_parameter(kwargs, 'gain', 0.7)
assert 0.0 < gain < 2.0, "Loop gain must be between 0 and 2"
thresh = get_parameter(kwargs, 'threshold', 0.0)
assert thresh >= 0.0
niter = get_parameter(kwargs, 'niter', 100)
assert niter > 0
fracthresh = get_parameter(kwargs, 'fractional_threshold', 0.1)
assert 0.0 < fracthresh < 1.0
comp_array = numpy.zeros(dirty.data.shape)
residual_array = numpy.zeros(dirty.data.shape)
for channel in range(dirty.data.shape[0]):
for pol in range(dirty.data.shape[1]):
if psf.data[channel, pol, :, :].max():
log.info(
"deconvolve_cube %s: Processing pol %d, channel %d" %
(prefix, pol, channel))
if window is None:
comp_array[channel, pol, :, :], residual_array[channel, pol, :, :] = \
hogbom(dirty.data[channel, pol, :, :], psf.data[channel, pol, :, :],
None, gain, thresh, niter, fracthresh, prefix)
else:
comp_array[channel, pol, :, :], residual_array[channel, pol, :, :] = \
hogbom(dirty.data[channel, pol, :, :], psf.data[channel, pol, :, :],
window[channel, pol, :, :], gain, thresh, niter, fracthresh, prefix)
else:
log.info(
"deconvolve_cube %s: Skipping pol %d, channel %d" %
(prefix, pol, channel))
comp_image = create_image_from_array(comp_array, dirty.wcs,
dirty.polarisation_frame)
residual_image = create_image_from_array(residual_array, dirty.wcs,
dirty.polarisation_frame)
else:
raise ValueError('deconvolve_cube %s: Unknown algorithm %s' %
(prefix, algorithm))
return comp_image, residual_image
def deconvolve_cube_complex(dirty: Image, psf: Image,
**kwargs) -> (Image, Image):
""" Clean using the complex Hogbom algorithm for polarised data (2016MNRAS.462.3483P)
The algorithm available is:
hogbom-complex: See: Pratley L. & Johnston-Hollitt M., (2016), MNRAS, 462, 3483.
This code is based upon the deconvolve_cube code for standard Hogbom clean available in ARL.
Args:
dirty (numpy array): The dirty image, i.e., the image to be deconvolved.
psf (numpy array): The point spread-function.
window (float): Regions where clean components are allowed. If True, entire dirty Image is allowed.
algorithm (str): Cleaning algorithm: 'hogbom-complex' only.
gain (float): The "loop gain", i.e., the fraction of the brightest pixel that is removed in each iteration.
threshold (float): Cleaning stops when the maximum of the absolute deviation of the residual is less than this value.
niter (int): Maximum number of components to make if the threshold `thresh` is not hit.
fractional_threshold (float): The predefined fractional threshold at which to stop cleaning.
Returns:
comp_image: clean component image.
residual_image: residual image.
"""
assert isinstance(dirty, Image), "Type is %s" % (type(dirty))
assert isinstance(psf, Image), "Type is %s" % (type(psf))
window_shape = get_parameter(kwargs, 'window_shape', None)
if window_shape == 'quarter':
qx = dirty.shape[3] // 4
qy = dirty.shape[2] // 4
window = np.zeros_like(dirty.data)
window[..., (qy + 1):3 * qy, (qx + 1):3 * qx] = 1.0
log.info(
'deconvolve_cube_complex: Cleaning inner quarter of each sky plane'
)
else:
window = None
psf_support = get_parameter(kwargs, 'psf_support', None)
if isinstance(psf_support, int):
if (psf_support < psf.shape[2] // 2) and (
(psf_support < psf.shape[3] // 2)):
centre = [psf.shape[2] // 2, psf.shape[3] // 2]
psf.data = psf.data[..., (centre[0] - psf_support):(centre[0] +
psf_support),
(centre[1] - psf_support):(centre[1] +
psf_support)]
log.info('deconvolve_cube_complex: PSF support = +/- %d pixels' %
(psf_support))
algorithm = get_parameter(kwargs, 'algorithm', 'msclean')
if algorithm == 'hogbom-complex':
log.info(
"deconvolve_cube_complex: Hogbom-complex clean of each polarisation and channel separately"
)
gain = get_parameter(kwargs, 'gain', 0.7)
assert 0.0 < gain < 2.0, "Loop gain must be between 0 and 2"
thresh = get_parameter(kwargs, 'threshold', 0.0)
assert thresh >= 0.0
niter = get_parameter(kwargs, 'niter', 100)
assert niter > 0
fracthresh = get_parameter(kwargs, 'fractional_threshold', 0.1)
assert 0.0 <= fracthresh < 1.0
comp_array = np.zeros(dirty.data.shape)
residual_array = np.zeros(dirty.data.shape)
for channel in range(dirty.data.shape[0]):
for pol in range(dirty.data.shape[1]):
if pol == 0 or pol == 3:
if psf.data[channel, pol, :, :].max():
log.info(
"deconvolve_cube_complex: Processing pol %d, channel %d"
% (pol, channel))
if window is None:
comp_array[channel, pol, :, :], residual_array[channel, pol, :, :] = \
hogbom(dirty.data[channel, pol, :, :], psf.data[channel, pol, :, :],
None, gain, thresh, niter, fracthresh)
else:
comp_array[channel, pol, :, :], residual_array[channel, pol, :, :] = \
hogbom(dirty.data[channel, pol, :, :], psf.data[channel, pol, :, :],
window[channel, pol, :, :], gain, thresh, niter, fracthresh)
else:
log.info(
"deconvolve_cube_complex: Skipping pol %d, channel %d"
% (pol, channel))
if pol == 1:
if psf.data[channel, 1:2, :, :].max():
log.info(
"deconvolve_cube_complex: Processing pol 1 and 2, channel %d"
% (channel))
if window is None:
comp_array[channel, 1, :, :], comp_array[
channel, 2, :, :], residual_array[
channel, 1, :, :], residual_array[
channel, 2, :, :] = hogbom_complex(
dirty.data[channel, 1, :, :],
dirty.data[channel, 2, :, :],
psf.data[channel, 1, :, :],
psf.data[channel, 2, :, :], None,
gain, thresh, niter, fracthresh)
else:
comp_array[channel, 1, :, :], comp_array[
channel, 2, :, :], residual_array[
channel, 1, :, :], residual_array[
channel, 2, :, :] = hogbom_complex(
dirty.data[channel, 1, :, :],
dirty.data[channel, 2, :, :],
psf.data[channel, 1, :, :],
psf.data[channel, 2, :, :],
window[channel, pol, :, :], gain,
thresh, niter, fracthresh)
else:
log.info(
"deconvolve_cube_complex: Skipping pol 1 and 2, channel %d"
% (channel))
if pol == 2:
continue
comp_image = create_image_from_array(
comp_array,
dirty.wcs,
polarisation_frame=PolarisationFrame('stokesIQUV'))
residual_image = create_image_from_array(
residual_array,
dirty.wcs,
polarisation_frame=PolarisationFrame('stokesIQUV'))
else:
raise ValueError('deconvolve_cube_complex: Unknown algorithm %s' %
algorithm)
return comp_image, residual_image
def create_test_image_from_s3(npixel=16384,
polarisation_frame=PolarisationFrame("stokesI"),
cellsize=0.000015,
frequency=numpy.array([1e8]),
channel_bandwidth=numpy.array([1e6]),
phasecentre=None,
fov=20,
flux_limit=1e-3) -> Image:
"""Create LOW test image from S3
The input catalog was generated at http://s-cubed.physics.ox.ac.uk/s3_sex using the following query::
Database: s3_sex
SQL: select * from Galaxies where (pow(10,itot_151)*1000 > 1.0) and (right_ascension between -5 and 5) and (declination between -5 and 5);;
Number of rows returned: 29966
For frequencies < 610MHz, there are three tables to use::
data/models/S3_151MHz_10deg.csv, use fov=10
data/models/S3_151MHz_20deg.csv, use fov=20
data/models/S3_151MHz_40deg.csv, use fov=40
For frequencies > 610MHz, there are three tables:
data/models/S3_1400MHz_1mJy_10deg.csv, use flux_limit>= 1e-3
data/models/S3_1400MHz_100uJy_10deg.csv, use flux_limit < 1e-3
data/models/S3_1400MHz_1mJy_18deg.csv, use flux_limit>= 1e-3
data/models/S3_1400MHz_100uJy_18deg.csv, use flux_limit < 1e-3
The component spectral index is calculated from the 610MHz and 151MHz or 1400MHz and 610MHz, and then calculated
for the specified frequencies.
If polarisation_frame is not stokesI then the image will a polarised axis but the values will be zero.
:param npixel: Number of pixels
:param polarisation_frame: Polarisation frame (default PolarisationFrame("stokesI"))
:param cellsize: cellsize in radians
:param frequency:
:param channel_bandwidth: Channel width (Hz)
:param phasecentre: phasecentre (SkyCoord)
:param fov: fov 10 | 20 | 40
:param flux_limit: Minimum flux (Jy)
:return: Image
"""
ras = []
decs = []
fluxes = []
if phasecentre is None:
phasecentre = SkyCoord(ra=+180.0 * u.deg,
dec=-60.0 * u.deg,
frame='icrs',
equinox='J2000')
if polarisation_frame is None:
polarisation_frame = PolarisationFrame("stokesI")
npol = polarisation_frame.npol
nchan = len(frequency)
shape = [nchan, npol, npixel, npixel]
w = WCS(naxis=4)
# The negation in the longitude is needed by definition of RA, DEC
w.wcs.cdelt = [
-cellsize * 180.0 / numpy.pi, cellsize * 180.0 / numpy.pi, 1.0,
channel_bandwidth[0]
]
w.wcs.crpix = [npixel // 2 + 1, npixel // 2 + 1, 1.0, 1.0]
w.wcs.ctype = ["RA---SIN", "DEC--SIN", 'STOKES', 'FREQ']
w.wcs.crval = [phasecentre.ra.deg, phasecentre.dec.deg, 1.0, frequency[0]]
w.naxis = 4
w.wcs.radesys = 'ICRS'
w.wcs.equinox = 2000.0
model = create_image_from_array(numpy.zeros(shape),
w,
polarisation_frame=polarisation_frame)
if numpy.max(frequency) > 6.1E8:
if fov > 10:
fovstr = '18'
else:
fovstr = '10'
if flux_limit >= 1e-3:
csvfilename = arl_path('data/models/S3_1400MHz_1mJy_%sdeg.csv' %
fovstr)
else:
csvfilename = arl_path('data/models/S3_1400MHz_100uJy_%sdeg.csv' %
fovstr)
log.info('create_test_image_from_s3: Reading S3 sources from %s ' %
csvfilename)
else:
assert fov in [
10, 20, 40
], "Field of view invalid: use one of %s" % ([10, 20, 40])
csvfilename = arl_path('data/models/S3_151MHz_%ddeg.csv' % (fov))
log.info('create_test_image_from_s3: Reading S3 sources from %s ' %
csvfilename)
with open(csvfilename) as csvfile:
readCSV = csv.reader(csvfile, delimiter=',')
r = 0
for row in readCSV:
# Skip first row
if r > 0:
ra = float(row[4]) + phasecentre.ra.deg
dec = float(row[5]) + phasecentre.dec.deg
if numpy.max(frequency) > 6.1E9:
alpha = (float(row[11]) - float(row[10])) / numpy.log10(
1400.0 / 610.0)
flux = numpy.power(10, float(row[10])) * numpy.power(
frequency / 1.4e9, alpha)
else:
alpha = (float(row[10]) - float(row[9])) / numpy.log10(
610.0 / 151.0)
flux = numpy.power(10, float(row[9])) * numpy.power(
frequency / 1.51e8, alpha)
if flux.any() > flux_limit:
ras.append(ra)
decs.append(dec)
fluxes.append(flux)
r += 1
csvfile.close()
assert len(fluxes) > 0, "No sources found above flux limit %s" % flux_limit
log.info('create_test_image_from_s3: %d sources read' % (len(fluxes)))
p = w.sub(2).wcs_world2pix(numpy.array(ras), numpy.array(decs), 1)
total_flux = numpy.sum(fluxes)
fluxes = numpy.array(fluxes)
ip = numpy.round(p).astype('int')
ok = numpy.where((0 <= ip[0, :]) & (npixel > ip[0, :]) & (0 <= ip[1, :])
& (npixel > ip[1, :]))[0]
ps = ip[:, ok]
fluxes = fluxes[ok]
actual_flux = numpy.sum(fluxes)
log.info('create_test_image_from_s3: %d sources inside the image' %
(ps.shape[1]))
log.info(
'create_test_image_from_s3: average channel flux in S3 model = %.3f, actual average channel flux in '
'image = %.3f' %
(total_flux / float(nchan), actual_flux / float(nchan)))
for chan in range(nchan):
for iflux, flux in enumerate(fluxes):
model.data[chan, 0, ps[1, iflux], ps[0, iflux]] = flux[chan]
return model
