home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Atari Mega Archive 1
/
Atari Mega Archive - Volume 1.iso
/
graphics
/
pbm
/
pbm_man.zoo
/
man1
/
pnmconvol.1
< prev
next >
Wrap
Text File
|
1994-08-27
|
1KB
|
67 lines
pnmconvol(1) USER COMMANDS pnmconvol(1)
NAME
pnmconvol - general MxN convolution on a portable anymap
SYNOPSIS
pnmconvol _✓c_✓o_✓n_✓v_✓o_✓l_✓u_✓t_✓i_✓o_✓n_✓f_✓i_✓l_✓e [_✓p_✓n_✓m_✓f_✓i_✓l_✓e]
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 aver-
age of the nearby pixels. The weights and the area to aver-
age 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.
Sun Release 4.0 Last change: 13 January 1991 1