Manual: pamtofits

Pamtofits User Manual(1)			   General Commands Manual			    Pamtofits User Manual(1)

NAME
       pamtofits - convert a Netpbm image into FITS format

SYNOPSIS
       pamtofits [-max f] [-min f] [pamfile]

DESCRIPTION
       This program is part of Netpbm(1).

       pamtofits  reads	 a  PNM	 or PAM image as input and produces a FITS (Flexible Image Transport System) file as output.
       The resolution of the output file is either 8 bits/pixel, or 16 bits/pixel, depending on the value of maxval  in	 the
       input  file.   If the input file is a PBM or PGM image, the output file consists of a single plane image (NAXIS = 2).
       If instead the input file is a PPM image, the output file will consist of a three-plane image (NAXIS =  3,  NAXIS3  =
       3).

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

       -min and -max tell pamtofits what "physical values" zero and maxval sample values, respectively, in the	input  image
       represent.  Physical values are a FITS concept.	pamtofits sets up the BSCALE and BZERO FITS header cards to indicate
       this information.

       The default for -min is 0 and for -max is the maxval, which means if you don't specify these options, the FITS physi‐
       cal values are in fact the original Netpbm sample values.

       pamtofits always sets up the FITS header DATAMIN and DATAMAX cards to indicate that the highest physical value in the
       image  is the one corresponding to the Netpbm maxval and the lowest is that corresponding to Netpbm zero.  This isn't
       really how those cards are supposed to be used, since the input image doesn't necessarily contain the  full  possible
       range of sample values.	It is a conservative approximation.

NOTES
   Pixel Order
       The  FITS  specification	 does not specify which data in the file corresponds to which pixel in the image (i.e. which
       bytes are the top left pixel, etc.).  Netpbm uses the common sense, most popular arrangement: row major, top to	bot‐
       tom,  left  to  right.  That means in a 10 wide by 20 high image, the first 10 pixels in the file are the top row and
       the last 10 are the bottom row.	Within each row, the first pixel is the leftmost one  and  the	last  pixel  is	 the
       rightmost one.

       Netpbm  has  always  done  that,	 since it first understood the FITS format in 1989, so it is something of a de facto
       standard.  Nobody reported trouble with that until 2008.

       However, at least some versions of ImageMagick and Gimp (as seen in 2008) use bottom to top order, so if you  use  on
       of  these to display a FITS image generated by pamtofits, it will appear upside down.  To fix that, use pamflip -top‐
       bottom on the image before feeding it to pamtofits.

       Since 2008, people have noted that NASA distributes FITS files with bottom to top order.

HISTORY
       pamtofits was originally pnmtofits and did not handle PAM input.	 It was extended and renamed in Netpbm 10.30  (Octo‐
       ber 2005).

       pnmtofits was itself an extension of pgmtofits, which was added to Pbmplus in 1989.

SEE ALSO
       fitstopnm(1), pam(1)

AUTHOR
       Copyright  (C)  1989 by Wilson H. Bent (whb@hoh-2.att.com), with modifications by Alberto Accomazzi (alberto@cfa.har‐
       vard.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/pamtofits.html

netpbm documentation				      25 September 2005				    Pamtofits User Manual(1)