The DitherII Package

Andy Fruchter, 30 June 1998

DitherII is an IRAF package for the removal of cosmic rays from
dithered, undersampled images.  It is to be used in conjunction
with the Dither package which has already been distributed as
a fully supported part of the STSDAS IRAF system.  For more
information on the original Dither package see http://ra.stsci.edu/STSDAS.html .

DitherII is a being distributed on a "shared risk" basis.  It should
be regarded as "beta" test software.  DitherII has already been
tried by a number of expert users; however, it has not yet been
widely tested, and the programs are not optimized.  They are scripts
written to test concepts.  If they prove successful, then faster, sleeker
versions will be installed in the official Dither package.

In the DitherII tar file you should find the following files:

README		-- this file	
deriv.cl	-- A cl script for taking the absolute derivative of an image
deriv.hlp	-- An IRAF help file for deriv.cl
ditherII.cl	-- The package cl file
driz_cr.cl	-- A cl script for finding blemishes in dithered images
driz_cr.hlp	-- An IRAF help file for driz_cr.cl
filename.cl	-- An ancillary task used by some of the tasks in this package
fileroot.cl	-- Another ancillary task used by some of the tasks in DitherII.
mask_head.cl	-- A cl script for preparing image masks for imcombine
mask_head.hlp	-- An IRAF help file for mask_head.cl
ditherII.ps	-- A paper describing the use of the tasks in this package.  
	

Installation:

uncompress ditherII.tar.Z
tar -xvf ditherII.tar .

will create a subdirectory called ditherII and will place the files
listed above in it.  

To run DitherII from IRAF place the following two lines in your login.cl:

set ditherII = /PATH/ditherII/
task ditherII=ditherII$ditherII.cl

where /PATH is the path to the ditherII directory.

Providing direct access to the help files requires an update to the
IRAF help database.  As this is just a beta release, we are avoiding
direct installation into IRAF.  Therefore, to access a help file
use the form

dI> help ditherII$driz_cr.hlp fi+

driz_cr.hlp is naturally the help file for the task driz_cr, and fi+ tells
help to read directly from this file rather than looking in the IRAF help
database.

If you really want ditherII to be fully installed as a package, speak
to your local IRAF guru.  They can install it as part of the local
package.