NAME

       fitstopnm - convert a FITS file into a PNM image

SYNOPSIS

       fitstopnm [-image=N] [-scanmax] [-printmax] [-min=f] [-max=f] [-omaxval=N [FITSfile]

       Minimum unique abbreviation of option is acceptable.  You may use double hyphens instead of single hyphen
       to  denote  options.  You may use white space in place of the equals sign to separate an option name from
       its value.

DESCRIPTION

       This program is part of Netpbm(1).

       fitstopnm reads a FITS (Flexible Image Transport System) file as input and produces a PPM  image  if  the
       FITS file consists of 3 image planes (NAXIS = 3 and NAXIS3 = 3), or a PGM image if the FITS file consists
       of 2 image planes (NAXIS = 2), or if you specify the -image option.

       Note  that  the PPM image is highly unlikely to be a true PPM image, as it is not normal for a FITS image
       to use the third axis as R, G, and B components of the pixels.  The most common interpretation when there
       are 3 axes is that the third one is time.  So the image is instead a pseudo-PPM in which the three sample
       values of a pixel represent something other than color components,  for  example  gray  levels  at  three
       instants (this variation on PPM is common in programs such as fitstopnm that predate the PAM format).

       If  you  work  with  FITS  images  with 3 axes, you should probably always use the -image option to avoid
       getting an unwanted pseudo-PPM image.

       The program tells you what kind of PNM image it is writing.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably  -quiet,  see   Common
       Options ), fitstopnm recognizes the following command line options:

       -image=N
              This  is  for  FITS  files  with three axes.  This option says that the third axis is for multiple
              images, and the option value N tells which one you want.

       -omaxval=N

              This is the maxval that the output PNM image is to have.

              By default, the maxval is the least possible to retain all the precision of the FITS input.   That
              means  the  difference  between  the  highest and lowest sample value in the input.  If the values
              range from -5 to 100, for example, the default maxval would be 106 and each PNM sample value would
              correspond to one FITS sample value.

              For a FITS input with floating point sample values, the precision  is  essentially  unlimited,  so
              this is not possible.  In that case, the default maxval is simply 255.

              This  option  was  new  in Netpbm 10.39 (June 2007).  Before that, the output maxval is always the
              default.

       -min=float

       -max=float

              You can use these options to override the min and max values as read from the FITS header  or  the
              image data if the header has no DATAMIN and DATAMAX keywords.

       -scanmax
              Use  this  option  to  force  the  program  to  scan the data even when the header has DATAMIN and
              DATAMAX.

       -printmax
              With this option, the program just prints the min and max  values  and  quits  without  doing  its
              normal job.

              This is for use in shell programs.  Example:

                  eval 'fitstopnm -printmax $filename | \
                  awk {min = $1; max = $2} \
                        END {print "min=" min; " max=" max}'

NOTES

   Pixel Order
       You may need to pass the output of fitstopnm through pamflip -topbottom.  See pamtofits

SEE ALSO

       pamtofits(1), pamflip(1), pgm(1)

AUTHOR

       Copyright  (C)  1989 by Jef Poskanzer, with modifications by Daniel Briggs (dbriggs@nrao.edu) and Alberto
       Accomazzi (alberto@cfa.harvard.edu).

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master  documentation
       is at

              http://netpbm.sourceforge.net/doc/fitstopnm.html

netpbm documentation                             02 August 2015                         Fitstopnm User Manual(1)