Pgmkernel User Manual(0) Pgmkernel User Manual(0)
pgmkernel - generate a convolution kernel
This program is part of Netpbm(1).
pgmkernel generates a convolution kernel that you can use with pnmcon-
vol. 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 everywhere beyond the specified kernel
width and height.
pgmkernel generates the output PGM file in the Plain (text) variation
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 (firstname.lastname@example.org).
netpbm documentation 10 December 1992 Pgmkernel User Manual(0)
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