Pgmabel User Manual(0) | Pgmabel User Manual(0) |

# 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(1)

**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(1) , pgm(5) ,

# 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

June 2002 | netpbm documentation |