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pnmconvol.man
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pnmconvol(1) AMIGA (13 January 1991) pnmconvol(1)
NAME
pnmconvol - general MxN convolution on a portable anymap
SYNOPSIS
pnmconvol convolutionfile [pnmfile]
DESCRIPTION
Reads two portable anymaps as input. Convolves the second
using the first, and writes a portable anymap as output.
Convolution means replacing each pixel with a weighted
average of the nearby pixels. The weights and the area to
average are determined by the convolution matrix. The
unsigned numbers in the convolution file are offset by
-maxval/2 to make signed numbers, and then normalized, so
the actual values in the convolution file are only relative.
Here is a sample convolution file; it does a simple average
of the immediate neighbors, resulting in a smoothed image:
P2
3 3
18
10 10 10
10 10 10
10 10 10
The convolution file will usually be a bitmap or graymap
instead of a pixmap, so that the same convolution gets
applied to each color component. However, if you want to
use a pixmap and do a different convolution to different
colors, you can certainly do that.
SEE ALSO
pnm(5)
AUTHOR
Copyright (C) 1989, 1991 by Jef Poskanzer.
Page 1 (printed 10/19/91)