# pgmabel

Updated: June 2002

Table Of Contents
## NAME

pgmabel - create cross section using Abel Integration for Deconvolution
## SYNOPSIS

**pgmabel**
[**-help**]
[**-axis** *axis*]
[**-factor** *factor*]
[**-pixsize** *pixsize*]
[**-left** | **-right**]
[**-verbose**]
[*filespec*]
## DESCRIPTION

This program is part of Netpbm.

**pgmabel** 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. **pgmabel** produces as output an image of
a cross-section of the image.
**pgmabel** does the calculation by performing the Abel Integration
for Deconvolution of an axial-symmetrical image by solving the system
of linear equations.
After integration, **pgmabel** weights all gray-values of one side
by the surface area of the calculated ring in square pixels divided by
4**factor* multiplied by the size of one pixel (*pixsize*).
With the **-verbose** option, **pgmabel** prints the weighting
factors.

Where the calculation generates a negative result, the output is black.

The computation is unstable against periodic structures with size 2 in
the vertical direction.

## OPTIONS

You can abbreviate any option to its shortest unique prefix.

**-help**
- Prints a help message.
**-axis** *axis*
- 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.
**-factor** *factor*
- User defined factor for enhancement of the output. Use a
*factor*
less than 1 for decreasing gary values. Default is 1.0.
**-pixsize** *pixsize*
- The size of a pixel for getting scale invariant. Default is 0.1.
**-left**
Calculate only the left side of the image. You cannot specify both
**left** and **right**.
**-right**
Analogous to **-left**.
**-verbose**
- print information about the calculation.

## EXAMPLE

Rotate a PGM image to get an image with a vertical axis of symmetry,
then calculate the cross section:

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

## SEE ALSO

**pnmrotate**,
**pgm**,
## HISTORY

This program was added to Netpbm in Release 10.3 (June 2002).

## AUTHOR

Volker Schmidt (lefti@voyager.boerde.de)

Copyright (C) 1997-2002 German Aerospace research establishment

## Table Of Contents