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Pnmsmooth User Manual(0) Pnmsmooth User Manual(0)
NAME
pnmsmooth - smooth out an image
SYNOPSIS
pnmsmooth [-width=cols] [-height=rows] [pnmfile] [-size]
Minimum unique abbreviations of options is acceptable. You may use
double hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate an option name from
its value.
DESCRIPTION
This program is part of Netpbm(1)
pnmsmooth smoothes out an image by replacing each pixel with the aver-
age of its width X height neighbors. It is implemented as a progam
that invokes pnmconvol with an appropriate convolution matrix.
OPTIONS
-width=cols
-height=rows
These options specify the dimensions of the convolution matrix.
Default dimensions are 3 wide and 3 high.
Before Netpbm 10.49 (December 2009), the maximum size of the
convolution matrix is limited by the maxval of the image such
that width * height * 2 must not exceed the maxval. (use
pamdepth to increase the maxval if necessary).
These options were new in Netpbm 10.32 (February 2006). Before
that, use -size.
-size This deprecated option exists in current Netpbm for backward
compatibility. It was obsoleted by -width and -height in Netpbm
10.32 (February 2006).
When you use this option, the first two program arguments are
the width and height, respectively, of the convolution matrix
and do the same thing as the -width and -height option values.
The third (optional) program argument is the input file name.
In reality, in old pnmsmooth, the width and height are two val-
ues of the -size option, but the modern Netpbm command syntax
paradigm doesn't allow an option with multiple values, so
instead -size is an option with no value and width and height
are program arguments. That has the fortunate effect of making
the following command mean the same in current pnmsmooth as in
old pnmsmooth:
pnmsmooth -size 5 5 infile.ppm >outfile.ppm
-dump=dumpfile
This options makes pnmsmooth only show you the convolution
matrix. It writes to Standard Output a pnmconvol -matrix option
value that represents the matrix. It does not invoke pnmconvol
and does not produce an output image.
Before Neptbm 10.49 (December 2009), this option is rather dif-
ferent. It takes a file name as a value, and it writes to that
file the convolution matrix as a PGM file (as used to be the
normal input for pnmconvol).
SEE ALSO
pnmconvol(1) , pnm(5)
HISTORY
Before Netpbm 10.32 (February 2006), pnmsmooth did not use the modern
Netpbm command line parser, so had an unconventional command line syn-
tax. Most importantly, you could not use an equal sign or double
hyphens in the options.
Before Netpbm 10.49 (December 2009), there was a -dump option. This
strange option caused pnmsmooth not to do any smoothing or produce any
output image but instead write the convolution matrix it would have
used, as PGM file such as pnmconvol used to use, to a file you specify.
The idea was you could then use that file with a separate invocation of
pnmconvol.
Then, in Netpbm 10.49, there was a rather different -dump option with a
similar purpose: It caused pnmsmooth to write to Standard Error a
string suitable as a value for the pnmconvol -matrix option (an option
that was new in Netpbm 10.49).
But in Netpbm 10.51 (June 2010), pnmconvol started using the even newer
pnmconvol -normalize option (new in 10.50), which made specifying the
convolution matrix for the kind of smoothing that pnmsmooth does triv-
ial, so -dump disappeared from pnmsmooth.
(There were also ease of implementation issues that kept us from simply
keeping the original -dump around for backward compatibility: As we
modified pnmsmooth to take advantage of the new features of pnmconvol,
which pnmsmooth uses internally, the information needed to implement
-dump was no longer available in the program).
netpbm documentation 19 December 2009 Pnmsmooth User Manual(0)
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