pgmkernel
generate a convolution kernel
see also :
pnmconvol - pnmsmooth
Synopsis
pgmkernel
[ -weight w ] width [
height ]
add an example, a script, a trick and tips
examples
no example yet ...
... Feel free to add your own example above to help other Linux-lovers !
description
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 + (j-height/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 format.
options
The optional
-weight flag should be a real number greater than -1.
The default value is 6.0.
bugs
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 also
pnmconvol ,
pnmsmooth
author
Alberto
Accomazzi (alberto[:at:]cfa.harvard[:dot:]edu).