pgmkernel - generate a convolution kernel
pgmkernel [ __-weight__ ''w''? width ''height''?
Generates a portable graymap array of size width x
height (or width x width if
height is not specified) to be used as a convolution
file by pnmconvol. The data in the convolution array
K are computed according to the formula:
K(i,j) = 1 / ( 1 + w * sqrt((i-width/2)^2 +
where w is a coefficient specified via the
-weight flag, and width and height are
the X and Y filter sizes.
The output PGM file is always written out in ASCII
The optional -weight flag 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
Alberto Accomazzi (email@example.com).