NAME

       mDiffExec - Re-project and mosaic your images, with background rectification

SYNOPSIS

       mDiffExec [-p projdir] [-d] [-n(o-areas)] [-s statusfile] diffs.tbl template.hdr diffdir

DESCRIPTION

       Runs mDiff on all the pairs identified by mOverlaps.

OPTIONS

       -p projdir
              Specifies path to the directory containing reprojected input images.

       -d     Turns on debugging.

       -n     No-area-images flag. Creates difference image without requiring _area FITS images

       -s statusfile
              Output and errors are sent to statusfile instead of to stdout

ARGUMENTS

       diffs.tbl
              Table generated by mOverlaps for the images in projdir.

       template.hdr
              FITS header template for output files.

       diffdir
              Path to output files.

RESULT

       FITS  images representing the differences for each pair of overlapping images.  nimages is
       the total number of images successfully processed, and nfailed is  the  number  of  images
       that  failed.   The  most  likely cause of failure is that the FITS images overlapped, but
       only in areas where they contained blank pixels (especially common in  images  with  large
       degree of rotation).

MESSAGES

       OK     [struct stat="OK", count=nimages, failed=nfailed]

       ERROR  MPI initialization failed

       ERROR  Cannot open status file: statusfile

       ERROR  Cannot access diffdir

       ERROR  diffdir is not a directory

       ERROR  Invalid image metadata file: filename

       ERROR  Need columns: cntr1 cntr2 plus minus diff

       ERROR  mDiff error

EXAMPLES

       First,  diffs.tbl  is  generated  using  mOverlaps.   Then mDiff can be run on reprojected
       images, using this template.hdr.

       $ mDiffExec -n -p projdir projdir/diffs.tbl template.hdr diffdir
              [struct stat="OK", count=42, failed=0]

BUGS

       The drizzle algorithm has been implemented but has not been tested in this release.

       If a header template contains  carriage  returns  (i.e.,  created/modified  on  a  Windows
       machine),  the cfitsio library will be unable to read it properly, resulting in the error:
       [struct stat="ERROR", status=207, msg="illegal character in keyword"]

       It is best for the background correction algorithms if the area described  in  the  header
       template  completely encloses all of the input images in their entirety. If parts of input
       images are "chopped off" by  the  header  template,  the  background  correction  will  be
       affected.  We  recommend  you  use  an expanded header for the reprojection and background
       modeling steps, returning to the originally desired header size for the final  coaddition.
       The default background matching assumes that there are no non-linear background variations
       in the individual images (and therefore in the  overlap  differences).  If  there  is  any
       uncertainty  in  this  regard, it is safer to turn on the "level only" background matching
       (the "-l" flag in mBgModel.

COPYRIGHT

       2001-2015 California Institute of Technology, Pasadena, California

       If your research  uses  Montage,  please  include  the  following  acknowledgement:  "This
       research  made use of Montage. It is funded by the National Science Foundation under Grant
       Number ACI-1440620, and was previously  funded  by  the  National  Aeronautics  and  Space
       Administration's  Earth Science Technology Office, Computation Technologies Project, under
       Cooperative Agreement Number  NCC5-626  between  NASA  and  the  California  Institute  of
       Technology."

       The  Montage  distribution  includes an adaptation of the MOPEX algorithm developed at the
       Spitzer Science Center.