NAME

       mBackground - Remove a background plane from a FITS image

SYNOPSIS

       mBackground [-d level] [-n(o-areas)] [-s statusfile] in.fits out.fits A B C

       mBackground  [-t]  [-d  level]  [-n(o-areas)]  [-s statusfile] in.fits out.fits images.tbl
       corrfile.tbl

DESCRIPTION

       Remove a background plane from a FITS image.  The background  correction  applied  to  the
       image  is specified as Ax+By+C, where (x,y) is the pixel coordinate using the image center
       as the origin, and (A,B,C)  are  the  background  plane  parameters  specified  as  linear
       coefficients.

OPTIONS

       -d level
              Turns on debugging to the specified level.

       -n     Indicates  that  no  area images are present (assumes equal weighting for each data
              pixel)

       -s statusfile
              mBackground output and errors will be written to statusfile instead of stdout.

       -t     Run in table mode. Starts a group of mBackground runs in parallel, reading off  the
              same  pair  of  tables  to determine which files and background corrections to work
              with. Recommended for running only on grids or parallel processors.

ARGUMENTS

       in.fits
              Input FITS file

       out.fits
              Output FITS file

       A B C  Corrections (as given by mFitplane or mFitExec)

       images.tbl
              When run as part of a GRID processing job, mBackground requires the image  metadata
              table to retrieve the filenames of images.

       corrections.tbl
              When  run  as  part  of  a  GRID  processing  job,  mBackground requires a table of
              corrections (from mFitplane and mFitExec) to apply to the corresponding image (from
              images.tbl).

RESULT

       Output FITS image with background subtraction applied.

MESSAGES

       OK     [struct stat = "OK"]

       ERROR  No status file name given

       ERROR  Cannot open status file: statusfile

       ERROR  No debug level given

       ERROR  Debug level string is invalid: string

       ERROR  Debug level value cannot be negative

       ERROR  Invalid input file filename

       ERROR  Invalid output file filename

       ERROR  A coefficient string is not a number

       ERROR  B coefficient string is not a number

       ERROR  C coefficient string is not a number

       ERROR  Invalid image metadata file: images.tbl

       ERROR  Image table needs columns cntr and fname

       ERROR  Hit end of image table without finding file name

       ERROR  Need columns: id,a,b,c in corrections file

       ERROR  Hit end of corrections table without finding data

       ERROR  FITS library error message

       ERROR  general error message

EXAMPLES

       The  following  is  sample  output  from  mFitplane  for  a  FITS  image, in.fits: [struct
       stat="OK",  a=-0.000144415,  b=-0.000133642,   c=-31.8984,   crpix1=758.5,   crpix2=-1032,
       xmin=-758.5,   xmax=-349.5,   ymin=1032,   ymax=1498,  xcenter=-555.007,  ycenter=1265.26,
       rms=0.576727]

       We use the plane coefficients calculated by mFitplane to subtract the background from  the
       image:

       $ mBackground projdir/in.fits bg_removed/in.fits -0.000144415 -0.000133642 -31.8984
              [struct stat="OK"]

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.