Manual: pnmsmooth

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 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 average of its width X height neighbors.  It is im‐
       plemented 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 ), pn‐
       msmooth 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 con‐
	      volution 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 com‐
	      mand 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 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 unconven‐
       tional 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 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  invoca‐
       tion 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 disap‐
       peared from pnmsmooth.

       (There were also ease of implementation issues that kept us from simply keeping the original -dump around  for  back‐
       ward 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).

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)