pgmkernel(1) General Commands Manual pgmkernel(1) NAME pgmkernel - generate a convolution kernel SYNOPSIS pgmkernel [ -weight w ] width [ height ] 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(1), pnmsmooth(1) AUTHOR Alberto Accomazzi (alberto AT cfa.edu). 10 December 1992 pgmkernel(1)
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