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  com-
       mand-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 ’uncol-
              lapse’ 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 com-
              mand-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 values before
              applying a median collapse. Default for these rejection  parame-
              ters is zero.

       -u or --uncollapse width
              This option actually performs a "reverse" collapse and will cre-
              ate 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-col-
              umn  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