iprocess_mask


This IDL facility provides an interface to F90 'process_mask' facility. For a given input binary mask, it can determine the angular distance in Radians of each valid (1 valued) pixel to the closest invalid (0 valued) pixel, with the option of ignoring small clusters of invalid pixels. The distance map can then be used to generate an apodized mask.

Location in HEALPix directory tree: src/idl/interfaces/iprocess_mask.pro 


FORMAT

IDL> IPROCESS_MASK, mask_in, distance_map,[ binpath=, filled_mask=, /help, hole_arcmin2=, hole_pixels=, keep_tmp_files=, /nested, ordering=, /ring, /silent, tmpdir=]


QUALIFIERS

mask_in
required input: input binary mask. It can be a FITS file, or a memory array containing the mask to process.
distance_map
optional output: double precision angular distance map in Radians. It can be a FITS file, or a memory array. It will have the same ordering as the input mask.


KEYWORDS

binpath=
full path to back-end routine default:$HEXE/process_mask, then $HEALPIX/bin/process_mask
- a binpath starting with / (or $\backslash$),   or $ is interpreted as absolute
- a binpath starting with ./ is interpreted as relative to current directory
- all other binpathes are relative to $HEALPIX

filled_mask=
optional output mask with holes smaller than hole_arcmin2 or hole_pixels filled in. Will have the same ordering as the input mask

/help
if set, prints extended help

hole_arcmin2
Minimal size (in arcmin2) of invalid regions to be kept (can be used together with hole_pixels, the result will be the largest of the two). default:0.0

hole_pixels
Minimal size (in pixels) of invalid regions to be kept (can be used together with hole_arcmin2, the result will be the largest of the two). default:0

/keep_tmp_files
if set, temporary files are not discarded at the end of the run

/nested
if set, signals that the mask read online is in NESTED scheme (does not apply to FITS file), see also /ring and Ordering

ordering=
either 'RING' or 'NESTED', ordering of online mask, see /ring and /nested

/ring
see /nested and Ordering above

/silent
if set, works silently

tmpdir=
directory in which are written temporary files default:IDL_TMPDIR (see IDL documentation)


DESCRIPTION

iprocess_mask is an interface to 'process_mask' F90 facility. It requires some disk space on which to write the parameter file and the other temporary files. Most data can be provided/generated as an external FITS file, or as a memory array.


RELATED ROUTINES

This section lists the routines related to iprocess_mask

idl
version 6.4 or more is necessary to run iprocess_mask.
process_mask
F90 facility called by iprocess_mask.
ialteralm
IDL Interface to F90 alteralm
ianafast
IDL Interface to F90 anafast and C++ anafast_cxx
ismoothing
IDL Interface to F90 smoothing
isynfast
IDL Interface to F90 synfast


EXAMPLE:

npix = nside2npix(256)
mask = replicate(1, npix) & mask[randomu(seed,100)*npix] = 0
iprocess_mask, mask, distance, /ring, /silent
mollview, distance
A binary mask in which 100 randomly located pixels are 0-valued (=invalid) is generated. Then the distance (in Radians) of the valid pixels to the closest invalid pixels is computed and plotted.

Version 3.31, 2017-01-06