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 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 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 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 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
       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 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)