Man Pages

pamgauss(1) - phpMan pamgauss(1) - phpMan

Command: man perldoc info search(apropos)  


Pamgauss User Manual(0)                                Pamgauss User Manual(0)



NAME
       pamgauss - create a two dimensional gaussian function as a PAM image


SYNOPSIS
       pamgauss width height -sigma=number [-maxval=number] [-tupletype=string]

       Minimum  unique  abbreviation  of option 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.



EXAMPLES
            pamgauss 3 3 -sigma=.5 -tupletype=GRAYSCALE | pamtopnm >gauss.pgm
            pnmconvol -nooffset gauss.pgm myimage.ppm >blurred.ppm


DESCRIPTION
       This program is part of Netpbm(1).

       pamgauss  generates a one-plane PAM image whose samples are a gaussian function of their distance from the cen-
       ter of the image.  I.e.  the sample value is highest in the center and goes down, in a bell curve shape, as you
       move away from the center.

       The values are scaled so that the volume under the surface of the two-dimensional Gaussian function is the max-
       val of the image.

       You can use this image as a convolution kernel with pnmconvol to blur an image.  (This technique  is  known  as
       Gaussian blurring).

       width  and  height  are the dimensions of the image that pamgauss generates.  Mathematically speaking, they are
       the domain of the two dimensional gaussian function.

       The sum of all the samples is equal to the image's maxval (within rounding error).  This is true  even  if  you
       clip  the  Gaussian  function  by  making the image too small.  If you want to be sure you get a whole Gaussian
       function, make sure that you choose a sigma and image dimensions so that if you made it any larger, the  sample
       values at the edges would be zero.

       The  output  image is PAM.  To make it usable with pnmconvol, specify -tupletype=GRAYSCALE so pnmconvol can use
       it as if it were PGM.  You must use the -nooffset option on pnmconvol because zero means zero in the  PAM  that
       pamgauss generates.


OPTIONS
       -sigma=number
              This  is  the sigma parameter of the Gaussian function (if it were a Gaussian probability function, this
              would be its standard deviation).  The higher the number, the more spread out  the  function  is.   Nor-
              mally,  you  want to make this number low enough that the function reaches zero value before the edge of
              your image.

              number is in units of pixels.

              This option is required.  There is no default.


       -maxval=number
              This is the maxval for the output image.  It defaults to 255.


       -tupletype=string
              This is the value of the "tuple_type" attribute of the created PAM image.  It can be any  string  up  to
              255 characters.  If you don't specify this, pamgauss generates a PAM with unspecified tuple type.




SEE ALSO
       pnmconvol(1), pamtopnm(1), pgmkernel(1), pamseq(1), pam(1)


HISTORY
       pamgauss was new in Netpbm 10.23 (July 2004).



netpbm documentation              8 May 2004           Pamgauss User Manual(0)