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Pgmkernel User Manual(0)                              Pgmkernel User Manual(0)

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       pgmkernel - generate a convolution kernel

       pgmkernel [-weight w] width  [height ]

       This program is part of Netpbm(1).

       pgmkernel  generates  a convolution kernel that you can use with pnmconvol.  The kernel is one where the weight
       of each location is inversely proportional to its distance from the center of the kernel.

       pgmkernel generates a PGM image of size width by height (or width by width if you don't specify height.

       pgmkernel computes the convolution function K as follows.

              K(i,j) = 1 / ( 1 + w * sqrt(i^2 + j^2))

       where w is a coefficient specified via the -weight option.  i and j are measured in pixels.  K is  zero  every-
       where beyond the specified kernel width and height.

       pgmkernel generates the output PGM file in the Plain (text) variation of PGM.

       The optional -weight value should be a real number greater than -1.  The default value is 6.0.

       The  computation  time is proportional to width*height.  This increases rapidly with the increase of the kernel
       size.  A better approach could be using a FFT in these cases.

       pnmconvol(1), pnmsmooth(1) pamgauss(1) pgm(1)

       Alberto Accomazzi (

netpbm documentation           10 December 1992       Pgmkernel User Manual(0)