pgmabel - Man Page

create cross section using Abel Integration for Deconvolution


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


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.


In addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common Options ), pgmabel recognizes the following command line options:

You can abbreviate any option to its shortest unique prefix.


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.


Calculate only the left side of the image.  You cannot specify both left and right.


Analogous to -left.


print information about the calculation.


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(1),


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


Volker Schmidt (

Copyright (C) 1997-2002 German Aerospace research establishment

Document Source

This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation is at


June 2002 netpbm documentation