pgmabel

   Updated: June 2002
   Table Of Contents

NAME

   pgmabel  - create cross section using Abel Integration for De-
convolution

SYNOPSIS

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

   You can abbreviate any option to its shortest unique prefix.

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 In-
tegration 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 di-
vided by 4*factor
   multiplied by the size of one pixel (pixsize). With the  -ver-
bose 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.  De-
fault 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  establish-
ment
     _________________________________________________________________



Table Of Contents

     * NAME
     * SYNOPSIS
     * DESCRIPTION
     * OPTIONS
     * EXAMPLE
     * SEE ALSO
     * HISTORY
     * AUTHOR

UNIX/Linux commands referenced on this page:

1. as
2. which
3. size
4. factor
5. pnmrotate