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 minimum and maximum values you want.
Values out of this interval are clipped to the given extremums. Pixels
lying in the interval remain unchanged.
You can clip values outside an interval to specified values 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