\
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.TH "Pgmabel User Manual" 1 "June 2002" "netpbm documentation"

.SH NAME
pgmabel - create cross section using Abel Integration for Deconvolution

.UN synopsis
.SH SYNOPSIS

\fBpgmabel\fP
[\fB-help\fP]
[\fB-axis\fP \fIaxis\fP]
[\fB-factor\fP \fIfactor\fP]
[\fB-pixsize\fP \fIpixsize\fP]
[\fB-left\fP | \fB-right\fP]
[\fB-verbose\fP]
[\fIfilespec\fP]

.UN description
.SH DESCRIPTION
.PP
This program is part of
.BR "Netpbm" (1)\c
\&.
.PP
\fBpgmabel\fP reads as input a PGM image, which it assumes to be an
image of a rotational symmetric transparent object.  The image must have
a vertical symmetry axis.  \fBpgmabel\fP produces as output an image of
a cross-section of the image.

\fBpgmabel\fP does the calculation by performing the Abel Integration
for Deconvolution of an axial-symmetrical image by solving the system
of linear equations.

After integration, \fBpgmabel\fP weights all gray-values of one side
by the surface area of the calculated ring in square pixels divided by
4*\fIfactor\fP multiplied by the size of one pixel (\fIpixsize\fP).
With the \fB-verbose\fP option, \fBpgmabel\fP prints the weighting
factors.
.PP
Where the calculation generates a negative result, the output is black.
.PP
The computation is unstable against periodic structures with size 2 in
the vertical direction.

.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
\&), \fBpgmabel\fP recognizes the following
command line options:
.PP
You can abbreviate any option to its shortest unique prefix.



.TP
\fB-help\fP
Prints a help message.

.TP
\fB-axis\fP \fIaxis\fP
Position of the axis of symmetry in the image in pixels from the left
edge of the image.  Default is the center of the image.

.TP
\fB-factor\fP \fIfactor\fP
User defined factor for enhancement of the output.  Use a \fIfactor\fP
less than 1 for decreasing gary values.  Default is 1.0.

.TP
\fB-pixsize\fP \fIpixsize\fP
The size of a pixel for getting scale invariant.  Default is 0.1.

.TP
\fB-left\fP
Calculate only the left side of the image.  You cannot specify both
\fBleft\fP and \fBright\fP.

.TP
\fB-right\fP
Analogous to \fB-left\fP.

.TP
\fB-verbose\fP
print information about the calculation.



.UN example
.SH EXAMPLE
.PP
Rotate a PGM image to get an image with a vertical axis of symmetry,
then calculate the cross section:

.nf
    pnmrotate 90 file.pgm | pgmabel -axis 140 >cross_section.pgm

.fi

.UN seealso
.SH SEE ALSO
.BR "pnmrotate" (1)\c
\&,
.BR "pgm" (1)\c
\&,

.UN history
.SH HISTORY
.PP
This program was added to Netpbm in Release 10.3 (June 2002).

.UN author
.SH AUTHOR
.PP
Volker Schmidt (lefti@voyager.boerde.de)
.PP
Copyright (C) 1997-2002 German Aerospace research establishment
.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/pgmabel.html
.PP