pnmconvol

Apply convolution matrix

$ pnmconvol [matrix.pgm] [input.pnm] > [output.pnm]

$ pnmconvol -matrix=[1,1,1;1,1,1;1,1,1] [input.pnm] > [output.pnm]

$ pnmconvol -matrix=[-1,-1,-1;-1,8,-1;-1,-1,-1] [input.pnm] > [output.pnm]

pnmconvol [options] convolution input

pnmconvol applies convolution matrix filters to PNM images for effects like blurring, sharpening, and edge detection. The convolution kernel can be specified as a PGM file or inline with the -matrix option.
Each output pixel is computed as the weighted sum of surrounding input pixels according to the kernel values. Part of the Netpbm toolkit for image processing.

CONVOLUTION

Matrix file or specification.

Input PNM file.

Inline matrix.

Normalize output.

Display help.

Part of Netpbm. Matrix defines effect. Slow for large kernels.

pnmconvol is part of Netpbm for convolution operations.

pamedge(1), pnmsmooth(1), netpbm(1)