Name
thresh - threshold a cube/image to another cube/image or
pixel map
Synopsis
thresh [options] <in> [out]
Description
thresh uses the same operation (thresholding) to give two
different kind of results. To get rid of peaks in a cube
for example (impulse noise, etc.), just give it the mini-
mum and maximum values you want. Values out of this inter-
val are clipped to the given extremums. Pixels lying in
the interval remain unchanged.
You can clip values outside an interval to specified val-
ues by using the -c and -C options.
In binary mode, the input must be a single image, and the
output is a binary image set to 1 for a pixel lying in the
interval and 0 outside. Use it to fix bad pixel maps from
a linear gain image for example.
Default mode is : thresholding to normal pixel values.
Default output name for file infile.fits is
infile.thr.fits
Options
-b or --binary
Changes mode to binary. Input cube must have only
one image, output is a pixel map.
-h or --highcut value
Fixes the high cut value.
-l or --lowcut value
Fixes the low cut value.
-c or --assignlow pixelvalue
assigns a value for pixels which lie under lowcut.
Defaults to lowcut itself.
-C or --assignhigh pixelvalue
assigns a value for pixels which lie above highcut.
Defaults to highcut itself.
Examples
To threshold all values outside the interval [12 ; 5000]
in the file in.fits, you would use:
> thresh -l 12 -h 5000 in.fits
Output file in this case is in.thr.fits
To set all values outside the interval [15 ; 1200] to 0 in
the file in.fits, and to output it into a file named
thd.fits, you would use:
> thresh -l 15 -c 0 -h 1200 -C 0 in.fits thd.fits
Files
Input files shall all comply with FITS format.
See Also
flat