pnmtofits
Updated: 25 September 2005
Table Of Contents
NAME
pnmtofits ‐ convert a PNM image into FITS format
SYNOPSIS
pnmtofits [‐max f] [‐min f] [pnmfile]
DESCRIPTION
This program is part of Netpbm.
pnmtofits reads a PNM 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).
You can find a full description of the FITS format in As‐
tronomy &
Astrophysics Supplement Series 44 (1981), page 363.
OPTIONS
‐min and ‐max tell pnmtofits what "physical values" zero and
maxval sample
values, respectively, in the input image represent. Physical
values are a
FITS concept. pnmtofits 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 PNM sample values.
pnmtofits 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 PNM maxval and the lowest is that corre‐
sponding to PNM
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.
HISTORYpamtofits was originally pnmtofits and did not handle PAM in‐
put. It was
extended and renamed in Netpbm 10.30 (October 2005).
SEE ALSO
fitstopnm, pnm
AUTHOR
Copyright (C) 1989 by Wilson H. Bent (whb@hoh‐2.att.com), with
modifications
by Alberto Accomazzi (alberto@cfa.harvard.edu).
_________________________________________________________________
Table Of Contents
* NAME
* SYNOPSIS
* DESCRIPTION
* OPTIONS
* HISTORY
* SEE ALSO
* AUTHOR
