-constvariance
|
float
|
use a constant value variance
for all pixels in the data. Most likely only applicable for radio data. |
| -datafile |
string |
Name of the FITS file which
contains the image to model. |
-debugimgs
|
toggle
|
Create images of the various
search directions/intermediate states generated during the minimisation
process. This creates LOTS of images, and is for debugging purposes only.
|
| -dofit |
toggle |
Flag to tell the program to
perform a parameter sweep over the ranges specified in the lens components file.
Otherwise the source will just be projected into an image using the starting values from the components file. |
| -dumpimg |
toggle
|
Flag to have the program create
a FITS file with the best-fit image & source for each combination
of
lens model parameters. The default names of the files are
"imagedump_mainX.fits" and "sourcedump_mainX.fits", where X is just a
number which increases each time.
|
-fixlambda
|
float
|
(Obsolete) For use with the "-useconjgrad"
flag. The algorithm tries to minimise the metrix C=χ2 - λS
where S is the entropy in the source. Normally, λ is varied so that the
χ2 reaches the target chisqu. You can fix it to some value
using this flag. Setting lambda to zero diables the entropy and allows
negative values in the source.
|
| -makemag |
toggle
|
Flag to make a pixel-by-pixel
magnification map in the source and image planes as well as text files
containing sets of points whcih describe the critical line and caustic.
The output files are
called "mag_src.fits", "mag_img_inv.fits", "critline.txt" and
"caustic.txt". The output file in the
image plane is actually 1/mag just because this is easy to calculate
from the way the program stores the weights matrix. When the program
runs through many lens models, then the magnifications will be
calculated for the last lens model. Usually, you would want to do this
for a unique lens model.
|
-mask
|
string
|
File name of a FITS file which
will be used as a user-defined mask in the image. The χ2
will
be calculated only for pixels in the region specified by the mask. The
FITS mask should be a 1 or 0 (floating point is OK). A value of 0
(FALSE) means "mask this pixel" which means "don't use it in χ2
calculations". So the area you want the χ2 calculation to be
performed over should be non-zeros.
|
-maxiter
|
int |
maximum number of iterations
performed in the Max Entropy procedure for each lens model. Default is
100. |
| -nice |
int |
Set the "nice" level. By default
the program runs at whatever the nice level of the calling shell is. |
| -noisefile |
string |
File name of the pixel-by-pixel
variance (σ2) for the data. Obviously must be the same
dimesions as the data file. If not supplied, the program will use the
overall variance in the data file as a (poor) guess for the variance in
each pixel.
|
| -normalisepsfmax |
toggle
|
instead of normalising the PSF
so that the total in the PSF is 1, normalise so that the max value in
the PSF is 1. |
| -paramfile |
string
|
File name of the list of lens
model components.
|
| -pixelratio |
float |
Sets the ratio in angular size
of the pixels between the image and source planes. E.g a pixelratio of
2
means that the angular size of a pixel in the source plane is 1/2 that
of an image pixel. |
-pixelres
|
float
|
The pixel resolution of the
image in arcseconds. You must
supply this number.
|
-psffile
|
string |
Name of the FITS file which
contains the PSF for the data. It is strongly recommended that this be
an odd sized image for symmetry. |
| -srcdefaultval |
float
|
The default value (or "sky"
value) for pixels in the source plane. This is the "A" parameter in the
Skilling & Bryan terminology. Must be > 0. Should be the same order of magnitude as the variance in a blank part of your image. (i.e. in a sky-dominated optical image, if the sky value is N photons, then the noise will be sqrt(N) and the srcdefaultval should be of order N. Take care with units, because the entropy constraint is technically relevant to the number of photons received. See the recommended units of the data below in the 'tips' section.)
NOTE: as of v1.1.0, this number is subtracted from the model source before the model images is calculated, which is a departure from the definition in the Lensview paper.
The reason for this change is to accommodate high SNR images and for the entropy constraint to reflect photon statistics (where applicable).
Practically, what this means is that the srcdefaultval can be set higher without detrimental effects to the models (because parts of the source model that don't affect the image model are zeroed before projection into the image plane). Using a higher value will allow the model to be closer to the data (hence noisier). As a general rule, you want this parameter to have the same magnitude as your variance, but smaller if possible to keep unnecessary structure out of your source model.
|
| -sourcefile |
string |
Name of the fits file for the
source. This image defines the size of the source plane.
|
-targetchisqu
|
float
|
The target chisqu which the Max
Ent algorithm tries to reach. Once this value is reached (or maxiter)
the algorithm stops. If you don't know what this number is, you can't be sure you have found the best fit.
Lensview makes a guess at what the target chisqu is, but it isn't
reliable. You need to know this number.
|
-useconjgrad
|
toggle
|
(Obsolete and no longer supported.) Instead of using Skilling &
Bryan MEM, use the simple conjugate gradient method instead. Sources
generated with conj gradient tend to me more noisy than those generated
with S&B MEM. With this option and "-fixlambda 0", one can disable
the entropy constraint entirely.
|
-useminfinder
|
toggle
|
rather than do a parameter sweep
(the default), use the downhill simplex method ("amoeba") to find the best
set of parameters. In this case, the values in the parameter file are
used as the starting boundary for the simplex. This overrides -dofit.
|