Manual: fitstopnm

Fitstopnm User Manual(1)			   General Commands Manual			    Fitstopnm User Manual(1)

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 con‐
       sists 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 some‐
       thing other than color components, for example gray levels at three instants (this variation on PPM is common in pro‐
       grams 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	 un‐
       wanted 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)