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Pamtofits User Manual(0)						 Pamtofits User Manual(0)

       pamtofits - convert a Netpbm image into FITS format

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

       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).

       -min and -max tell pamtofits what 'physical values' zero and maxval sample values, respec-
       tively, 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 physical 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 sup-
       posed to be used, since the input image doesn't	necessarily  contain  the  full  possible
       range of sample values.	It is a conservative approximation.

   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 the top left pixel, etc.).  Netpbm uses the  common
       sense, most popular arrangement: row major, top to bottom, 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.

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

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

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

       fitstopnm(1) , pam(5)


       Copyright  (C)  1989  by Wilson H. Bent (whb@hoh-2.att.com), with modifications by Alberto
       Accomazzi (alberto@cfa.harvard.edu).

netpbm documentation			25 September 2005		 Pamtofits User Manual(0)
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