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

       pgmabel - 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 caculation generates a negative result, the output is black.

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

       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.

              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

       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

netpbm documentation               June 2002            Pgmabel User Manual(0)