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ccdsmooth - smoothing of an image map (2D or 3D)
ccdsmooth in=image
out=image [parameter=value]
ccdsmooth will smooth an image cube
through a simple convolution (no FFT). The smoothing beam must be circular/spherical,
or smoothing must be done independantly per coordinate by calling ccdsmooth
multiple times using the dir= keyword (see below).
The following
parameters are recognized in any order if the keyword is also given:
- in=in-file
- input file, in Image(5)
format [no default]
- out=out-file
- output file, will
be in Image(5)
format [no default]
- gauss=value
- Beam size (FWHM, note FWHM
= 2*sqrt(2*ln(2)
) = 2.355 * sigma) of a gaussian smoothing kernel. Note
this is size of the used smoothing kernel, NOT the resulting beam in the
output map. If this parameter is used, the parameter smooth is ignored [default:
not used].
- dir=x|y|z
- Direction of smoothing. This gives the flexibility of
smoothing in x, y and/or z separately. Note that when smoothing in more
than one coordinate the beam is forced to be circular. [default: xy].
- smooth=array
- Smoothing array, should be at least 1 number, prefarably normalized to
unity for sake for conservation of units (mass per unit square length).
The program does not normalize the beam to unity. Example is e.g. the Hanning
smoothing: "0.25,0.5,0.25". [default: 0.25,0.5,0.25]. This parameter is only used
if gauss parameter is not used.
- nsmooth=value
- Number of times the above
smoothing kernel is applied over the data, just in case you wanted to
be wasteful. [default: 1].
- bad=bad_value
- Input pixel value which to skip
in smoothing. [Default: not used]
- cut=cutoff_value
- Value at which to cutoff
the gaussian beam. [Default: 0.01]
ccdfill(1NEMO)
, snapccd(1NEMO)
,
snapsmooth(1NEMO)
, snapgrid(1NEMO)
, image(5NEMO)
With 68881 on SUN 3/50 (~16Mhz) and 200*200 map - old program (pre-V2.1)
Nbeam=17 54"
Nbeam=33 98"
Nbeam=47 140"
BugsSmoothing a map which has already been smoothed will result in an incorrect
header - shouldn't it be the simple sum of squares?? AuthorPeter Teuben Files
src/image/trans ccdsmooth.c ccdsmooth.1
29-jun-87 V1.0: Created as module from CCD program PJT
30-Jun-87 V1.1: improved 'struct' filestructure PJT
9-jul-87 V1.2: keyword 'dir' and keyword order changed PJT
1-jun-88 V2.0: new filestruct, although code is same PJT
5-feb-89 V2.2: general 3D smoothing PJT
11-sep-91 some additional comments PJT
12-mar-98 V3.1: added cut=, fixed fwhm=0.0 PJT
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