# pgmabel

Updated: June 2002
Index

## NAME

pgmabel: create cross section using Abel Integration for Deconvolution

## SYNOPSIS

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

You can abbreviate any option to its shortest unique prefix.

## DESCRIPTION

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 caculation generates a negative result, the output is black.

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

## OPTIONS

-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

## Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLE
SEE ALSO
HISTORY
AUTHOR