Name
       collapse - collapse an image along X or Y

Synopsis
       collapse [options] <in> [out]

Description
       collapse  is  used  to  create  a  1D signal from an input
       image, collapsing pixels along the X or Y  direction.  The
       default  collapsing  method  is a simple sum of all pixels
       along lines or columns. A median collapse (-m  option)  is
       done  by  keeping only the median value for each processed
       line or column. A number of lowest/highest pixels  can  be
       rejected before the median is computed, see the -r option.

       The output is an ASCII file containing  two  columns.  The
       first  column  contains the X or Y pixel position, and the
       second column contains the  collapsed  value.  The  output
       file  name  is  either provided on the command-line as the
       last argument, or will be built as:
       If the input name is inputname.fits, the  output  name  is
       inputname_line.

       You  can also request the output to be a FITS file, i.e. a
       FITS image with a  single  line.  See  the  -f  or  --fits
       option.

Options
       -d or --dir x | y
              Collapse  along the X or Y direction. Default is to
              collapse along the Y direction, i.e. the output  is
              a  line  of  pixels, each pixel being computed as a
              collapse of the column it belongs to.

       -f or --fits
              Save the result to a FITS file containing a  single
              line,  instead  of an ASCII file. This is useful as
              input if you want to `uncollapse' the image.

       -g or --gnuplot
              Activate a gnuplot output. This  option  will  only
              work  if gnuplot is installed for your user account
              and accessible from the command-line.

       -m or --median
              Collapse the image with  a  median  method,  rather
              than a simple sum.

       -r or --reject `lo hi'
              Rejects the `lo' lowest and `hi' highest pixel val-
              ues before applying a median collapse. Default  for
              these rejection parameters is zero.

       -u or --uncollapse width
              This  option actually performs a "reverse" collapse
              and will create a 2d image from a  single  line  or
              column.  This  is  useful  to subtract out from the
              initial image some row or column-specific  defects.
              With  this  option,  the  input file must be a FITS
              file, which means that you should have used the  -f
              or  --fits  option previously to save the collapsed
              image to a one-row or one-column  FITS  image.  The
              specified width indicates the size you want to give
              to this new image, in the newly created  direction.
              This option is incompatible with all others.

Examples
       Collapse  the  image  `im.fits'  along Y, with simple sum.
       Keep default output name `im_line'.
       collapse im.fits

       Collapse the image `im.fits' along X, with median collapse
       without rejection, keep default output name `im_line':
       collapse -d x -m im.fits

       Collapse the image `im.fits' along X, with median collapse
       rejecting the 80 low and 90 high pixels, naming the output
       `coll_line':
       collapse -d x -m -r `80 90' im.fits coll_line