This IDL facility allows the median filtering of a Healpix map.
Location in HEALPix directory tree:
MEDIAN_FILTER (InputMap, Radius, MedianMap [,ORDERING=, /RING, /NESTED, /FILL_HOLES, /DEGREES, /ARCMIN])
either an IDL array containing a full sky Healpix map to filter ('online' usage),
or the name of an external FITS file containing a full sky or cut sky map
radius of the disk on which the median is computed.
It is in Radians, unless /DEGREES or /ARCMIN are set
either an IDL variable containing on output the filtered map,
or the name of an external FITS file to contain the map. Should be of
same type of InputMap. Flagged pixels (ie, having the value
!healpix.bad_value) are left unchanged, unless /FILL_HOLES is set.
- If set, Radius is in arcmin rather than radians
- If set, Radius is in degrees rather than radians
- If set, flagged pixels are replaced with the
median of the valid pixels found within a distance Radius. If
there are any.
- Same as ORDERING='NESTED'
- Healpix map ordering, should be either 'RING' or 'NESTED'. Only
applies to 'online' usage.
- Same as ORDERING='RING'
median_filter allows the median filtering of a Healpix map. Each pixel
of the output map is the median value of the input map pixels found within a disc of given
radius centered on that pixel. Flagged
pixels can be either left unchanged or 'filled in' with that same scheme.
If the map is polarized, each of the three Stokes components is filtered
The input and output can either be arrays or FITS files, but they to be both
arrays or both FITS files.
This section lists the routines related to median_filter
- version 6.1 or more is necessary to run median_filter
Writes in 'med.fits' the median filtered map of 'map.fits' using a disc radius
of 10 arcmin
Returns in med the median filtered map of map using a disc radius
of 0.5 degrees