man > pnmsmooth(1)

Pnmsmooth User Manual(1)               General Commands Manual              Pnmsmooth User Manual(1)

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 sep‐
       arate 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 average of its width X
       height neighbors.  It is implemented as a program that invokes pnmconvol with an  appropriate
       convolution matrix.


OPTIONS
       In  addition  to  the options common to all programs based on libnetpbm (most notably -quiet,
       see  Common Options ), pnmsmooth recognizes the following command line 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 values 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 Stan‐
              dard  Output a pnmconvol -matrix option value that represents the matrix.  It does not
              invoke pnmconvol and does not produce an output image.

              Before Netpbm 10.49 (December 2009), this option is rather different.  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(1)


HISTORY
       Before  Netpbm  10.32  (February  2006), pnmsmooth did not use the modern Netpbm command line
       parser, so had an unconventional command line syntax.  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 convolu‐
       tion 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 trivial, 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  imple‐
       ment -dump was no longer available in the program).

DOCUMENT SOURCE
       This  manual  page  was  generated by the Netpbm tool 'makeman' from HTML source.  The master
       documentation is at

              http://netpbm.sourceforge.net/doc/pnmsmooth.html

netpbm documentation                      19 December 2009                  Pnmsmooth User Manual(1)