Pgmkernel User Manual(0) Pgmkernel User Manual(0)Table Contents ⟨#index⟩
NAMEpgmkernel - generate a convolution kernel
SYNOPSISpgmkernel [-weight w] width [height ]
DESCRIPTION
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
of PGM.
OPTIONS
The optional -weight value should be a real number greater than -1.
The default value is 6.0.
LIMITATIONS
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.
SEE ALSOpnmconvol(1), pnmsmooth(1)pamgauss(1)pgm(1)AUTHOR
Alberto Accomazzi (alberto@cfa.harvard.edu).
netpbm documentation 10 December 1992 Pgmkernel User Manual(0)
