saltfpmask

Name

saltfpmask – Mask the pixels outside the circular entrance aperture in a Fabry-Perot image. The mask value may be a specified constant or the biweight of the pixel values in a specified annulus of the image.

Usage

saltfpmask images methodout prefix/suffix/outfile maskmethod maskvalue masklogfile logfile useconfig configfile verbose

Parameters

images

String. List of FITS images to prepare. Data can be provided as a comma-separated list, or a string with a wildcard (e.g. ‘images=S20061210*.fits’), or a foreign file containing an ascii list of image filenames. For the ascii list option, the filename containing the list must be provided preceded by a ‘@’ character, e.g. 'images=@listoffiles.lis‘. The list can contain data files from multiple SALT instruments.

outimage

String. A list of images. Data can be provided as a comma-separated list, or a string with a wildcard (e.g. ‘outimages=rS20061210*.fits’), or a foreign file containing an ascii list of image filenames. For ascii list option, the filename containing the list must be provided preceded by a ‘@’ character, e.g. 'outimages=@listoffiles.lis‘. This list must be of the same size as the images argument list.

outpref

String. If the outpref string is non-zero in length and contains characters other than a blank space, it will override any value of the outimages argument. Output file names will use the name list provided in the images argument, but adding a prefix to each output file defined by outpref. An absolute or relative directory path can be included in the prefix, e.g. ‘outpref=/Volumes/data/p’.

axc

Float. Estimate of the aperture central x pixel value.

ayc

Float. Estimate of the aperture central y pixel value.

arad

Float. Estimate of the image aperture radius in pixels.

maskmethod

String. Method to determine the mask value. Either a ‘constant’ mask value or a value derived from a specified ‘region’.

maskvalue

Float. If the user chooses to mask the image with a particular value, the input the mask value.

radi

Float. Inner radius for maskvalue calculation. If the user chooses to use a mask value drawn from the bi-weight of the pixel values in a specified annulus of the image, they will imput the inner and outer radii of of the region radi and rado and the routine will calculate the mask value derived from the specified annulus.

rado

Float. Outer radius for maskvalue calculation. If the user chooses to use a mask value drawn from the bi-weight of the pixel values in a specified annulus of the image, they will imput the inner and outer radii of of the region radi and rado and the routine will calculate the mask value derived from the specified annulus.

(clobber)

Hidden boolean. If set to ‘yes’ files contained within the outpath directory will be overwritten by newly created files of the same name.

logfile

String. Name of an ascii file for storing log and error messages written by the task. The file may be new, or messages can also be appended to a pre-existing file.

verbose

Boolean. Verbose (yes) or quiet (no) execution of the routine.

Description

This program masks the pixels outside the circular entrance aperture in a Fabry-Perot image. The pixels are replaced with a specified constant or the mean of a annulus of pixels values as specificied by the user.

The program will mask all pixels beyond the radius of arad based on the center of the image being at axc, ayc. If the user selects maskmethod=’constant’, a constant value specified by maskvalue will be used for all of the pixels. If the user selects maskmethod=’region’, the mean value for all of the pixels in the region between radi to rado will be used to replace the pxiels.

Examples

1. To mask an image using input axc and axy parameters contained in the parameter file pfp.par:

   --> saltfpmask images=test.fits outimages=maskedtest.fits outpref=''
   maskmethod=r radi=500.0 rado=600.0 clobber=y logfile=salt.log verbose=yes

Time and disk requirements

Individual unbinned full frame RSS image files can be 112MB in size. It is recommended to use workstations with a minimum of 512MB RAM. On a linux machine with 2.8 Ghz processor and 2 Gb of RAM, one 2051x2051 image in 0.85 sec.

Bugs and limitations

Send feedback and bug reports to salthelp@saao.ac.za

See also

TBD