pamgauss



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]  [-tuple-
       type=string]

       Minimum unique abbreviation of option is acceptable.  You may use  dou-
       ble  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 center 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 area under the surface  of  the  two-
       dimensional Gaussian function is the maxval of the image.

       You  can use this image, converted to PGM, as a convolution kernel with
       pnmconvol to blur an image.  (This technique is known as Gaussian blur-
       ring).

       width  and  height are the dimensions of the image that pamgauss gener-
       ates.  Mathematically speaking, they are the domain of the  two  dimen-
       sional 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  dimen-
       sions so that if you made it any larger, the sample values at the edges
       would be zero.

       The output image is PAM.  To turn it into a PGM that you can  use  with
       pnmconvol,  specify  -tupletype=GRAYSCALE  and  pass the output through
       pamtopnm.  You must use the -nooffset option on pnmconvol because  zero
       means zero in the PAM that pamgauss generates.



DESCRIPTION

       This program is part of Netpbm(1).



       -sigma=number
              This is the sigma parameter of the Gaussian function (if it were
              a Gaussian probability function, this would be its the  standard
              deviation).   The  higher  the  number,  the more spread out the
              function is.  Normally, 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)

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