\
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.TH "Sgitopnm User Manual" 1 "25 April 2014" "netpbm documentation"

.SH NAME
sgitopnm - convert a SGI image file to PNM

.UN synopsis
.SH SYNOPSIS

\fBsgitopnm\fP

[\fB-verbose\fP]

[\fB-channel\fP \fIc\fP]

[\fISgiFileName\fP]


.UN description
.SH DESCRIPTION
.PP
This program is part of
.BR "Netpbm" (1)\c
\&.
.PP
\fBsgitopnm\fP reads an SGI image file as input and produces a PGM
image for a 2-dimensional (1- or 2-channel) input file, and a PPM image for
a 3-dimensional (3 or more channels) input file.
.PP
Alternatively, the program produces a PGM image of any one of the
channels in the input file.
.PP
Before Netpbm 10.67 (June 2014), \fBsgitopnm\fP does not work on 2-channel
SGI images.  It fails if you try.
.PP
If you don't specify the \fISgiFileName\fP argument, input is from
Standard Input.
.PP
Before Netpbm 10.67 (June 2014), \fBsgitopnm\fP requires its input to
be a seekable file, so for example you can't feed it from a pipe.


.UN options
.SH OPTIONS
.PP
In addition to the options common to all programs based on libnetpbm
(most notably \fB-quiet\fP, see 
.UR index.html#commonoptions
 Common Options
.UE
\&), \fBsgitopnm\fP recognizes the following
command line options:


.TP
\fB-verbose\fP
Give some information about the SGI image file.

.TP
\fB-channel\fP \fIn\fP
Extract channel \fIn\fP of the image as a PGM image.
.sp
Without this option, \fBsgitopnm\fP extracts the first 3 channels as a PPM
image or, if the input has 1 or 2 channels, extracts the first channel as a
PGM image.
.sp
A 2-channel image is grayscale plus transparency, so you can get
the transparency information with \fB-channel=2\fP.  You could then
combine them into a PAM image of tuple type GRAYSCALE_ALPHA with
\fBpamstack\fP.



.UN references
.SH REFERENCES
.PP
The SGI image format specification version 1.0 is at
ftp://ftp.sgi.com/graphics/grafica/sgiimage.html .
.PP
There is an example SGI file at 
https://github.com/ZaaLabs/ZaaIL-TestImages/tree/master/SGI .


.UN seealso
.SH SEE ALSO
.BR "pnm" (1)\c
\&,
.BR "pam" (1)\c
\&,
.BR "pnmtosgi" (1)\c
\&,
.BR "pamstack" (1)\c
\&


.UN author
.SH AUTHOR
.PP
Copyright (C) 1994 by Ingo Wilken
(\fI
Ingo.Wilken@informatik.uni-oldenburg.de\fP)
.SH DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML
source.  The master documentation is at
.IP
.B http://netpbm.sourceforge.net/doc/sgitopnm.html
.PP