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Pgmkernel User Manual(0) Pgmkernel User Manual(0) Table ContentsNAMEpgmkernel - generate a convolution kernelSYNOPSISpgmkernel[-weightw]width[height]DESCRIPTIONThis program is part of Netpbm(1).pgmkernelgenerates a convolution kernel that you can use withpnmconvol. The kernel is one where the weight of each location is inversely proportional to its distance from the center of the kernel.pgmkernelgenerates a PGM image of sizewidthbyheight(orwidthbywidthif you don't specifyheight.pgmkernelcomputes the convolution function K as follows. K(i,j) = 1 / ( 1 + w * sqrt(i^2 + j^2)) wherewis a coefficient specified via the-weightoption.iandjare measured in pixels. K is zero every- where beyond the specified kernel width and height.pgmkernelgenerates the output PGM file in the Plain (text) variation of PGM.OPTIONSThe optional-weightvalue should be a real number greater than -1. The default value is 6.0.LIMITATIONSThe computation time is proportional towidth*height. This increases rapidly with the increase of the kernel size. A better approach could be using a FFT in these cases.SEEALSOpnmconvol(1), pnmsmooth(1) pamgauss(1) pgm(1)AUTHORAlberto Accomazzi (alberto). netpbm documentation 10 December 1992 Pgmkernel User Manual(0)ATcfa.edu