NAME

       pgmmorphconv - perform morphological convolutions: dilation, erosion

SYNOPSIS

       pgmmorphconv [
        -erode |
        -dilate |
        -open |
        -close |
        -gradient ] templatefile [pgmfile]

       Minimum unique abbreviation of option is acceptable.  You may use double hyphens instead of single hyphen
       to  denote  options.  You may use white space in place of the equals sign to separate an option name from
       its value.

DESCRIPTION

       This program is part of Netpbm(1).

       pgmmorphconv performs morphological convolutions on a PGM image: dilation and erosion.

       pgmmorphconv performs a "topological" convolution.  For each pixel of the input,  pgmmorphconv  generates
       an  output pixel in the same position.  To determine the intensity of the output pixel, pgmmorphconv lays
       the template image over the input image such that the middle pixel of the  template  is  over  the  input
       pixel  in  question.  pgmmorphconv looks at the input pixels underneath each white pixel in the template.
       For a dilation, the maximum intensity of all those pixels is the intensity of the output pixel.   For  an
       erosion, it is the minimum.

       Thus,  the  dilation  effect  is  that  bright areas of the input get bigger and dark areas smaller.  The
       erosion effect is the opposite.  The simplest template image would be one  with  a  white  pixel  in  the
       middle  and  the  rest black.  This would produce an output image identical to the input.  Another simple
       template image is a fully white square.  This causes bright or dark areas to expand in all directions.  A
       template image that is white on the left side and black on the right would smear the image to the right.

       The template file named by templatefile contains the template image as a PBM image.  It must have an  odd
       number  of  rows  and  an odd number of columns, so there is a definite middle pixel.  It must contain at
       least one white pixel.

       This is similar to the continuous convolution done by pnmconvol, except that with  pnmconvol  the  output
       intensity is a weighted average of nearby input pixels instead of a minimum or maximum.

       This  convolution changes the three Minkowski integrals in a predefined way, and can be used to filter an
       image to enhance certain features, to ease their automatic recognition.

OPTIONS

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

       The options -erode and -dilate obviously produce an erosion or dilation, respectively.

       The  -open  option causes pgmmorphconv to perform first an erode and then a dilate operation.  The -close
       option causes a dilate first and then an erode.  If you specify none of these options, it is the same  as
       -dilate.

       With  -gradient,  pgmmorphconv produces an image which is the difference between the eroded image and the
       dilated image.  -gradient was new in Netpbm 10.70 (March 2015).

SEE ALSO

       •

              pgmminkowski(1)

       •

              pnmconvol(1)

       •

              pgm(1)

       For more information about morphological convolutions, see e.g.

       •

               J.S. Kole, K. Michielsen, and H. De Raedt, "Morphological Image Analysis  of  Quantum  Motion  in
              Billiards", Phys. Rev. E 63, 016201-1 - 016201-7 (2001)

       •      K.  Michielsen  and H. De Raedt, "Integral-Geometry Morphological Image Analysis", Phys. Rep. 347,
              461-538 (2001).

AUTHORS

       Luuk van Dijk, 2001.

       Based on work which is Copyright (C) 1989, 1991 by Jef Poskanzer.

DOCUMENT SOURCE

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

              http://netpbm.sourceforge.net/doc/pgmmorphconv.html

netpbm documentation                              29 March 2015                      Pgmmorphconv User Manual(1)