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  progam  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 ⟨index.html#commonoptions⟩ ), 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