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Pgmmorphconv User Manual(0)                        Pgmmorphconv User Manual(0)



NAME
       pgmmorphconv - perform morphological convolutions: dilation, erosion


SYNOPSIS
       pgmmorphconv [ -erode | -dilate | -open | -close ] 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 out-
       put 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  maxi-
       mum 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 inten-
       sity 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.

       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.


SEE ALSO
       ?       pgmminkowski(1)

       ?       pnmconvol(1)

       ?       pgm(1)


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


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


       ?
               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)




AUTHORS
       Luuk van Dijk, 2001.

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



netpbm documentation            29 October 2002    Pgmmorphconv User Manual(0)