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.

Montage 5                                           Dec 2016                                        MDIFFEXEC(1)