1Pamgauss User Manual(0)                                Pamgauss User Manual(0)
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NAME

6       pamgauss - create a two dimensional gaussian function as a PAM image
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SYNOPSIS

10       pamgauss   width   height   -sigma=number   [-maxval=number]   [-tuple‐
11       type=string]
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13       Minimum unique abbreviation of option is acceptable.  You may use  dou‐
14       ble  hyphens  instead  of single hyphen to denote options.  You may use
15       white space in place of the equals sign to separate an option name from
16       its value.
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EXAMPLES

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

26       This program is part of Netpbm(1).
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28       pamgauss  generates  a one-plane PAM image whose samples are a gaussian
29       function of their distance from the center of  the  image.   I.e.   the
30       sample  value  is  highest in the center and goes down, in a bell curve
31       shape, as you move away from the center.
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33       The values are scaled so that the volume under the surface of the  two-
34       dimensional Gaussian function is the maxval of the image.
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36       You  can  use this image as a convolution kernel with pnmconvol to blur
37       an image.  (This technique is known as Gaussian blurring).
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39       width and height are the dimensions of the image that  pamgauss  gener‐
40       ates.   Mathematically  speaking, they are the domain of the two dimen‐
41       sional gaussian function.
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43       The sum of all the samples is  equal  to  the  image's  maxval  (within
44       rounding  error).   This is true even if you clip the Gaussian function
45       by making the image too small.  If you want to be sure you get a  whole
46       Gaussian  function,  make sure that you choose a sigma and image dimen‐
47       sions so that if you made it any larger, the sample values at the edges
48       would be zero.
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50       The  output  image  is  PAM.  To make it usable with pnmconvol, specify
51       -tupletype=GRAYSCALE so pnmconvol can use it as if it  were  PGM.   You
52       must  use  the -nooffset option on pnmconvol because zero means zero in
53       the PAM that pamgauss generates.
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OPTIONS

57       -sigma=number
58              This is the sigma parameter of the Gaussian function (if it were
59              a  Gaussian  probability  function,  this  would be its standard
60              deviation).  The higher the number,  the  more  spread  out  the
61              function  is.  Normally, you want to make this number low enough
62              that the function reaches zero value before  the  edge  of  your
63              image.
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65              number is in units of pixels.
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67              This option is required.  There is no default.
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70       -maxval=number
71              This is the maxval for the output image.  It defaults to 255.
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74       -tupletype=string
75              This  is  the value of the "tuple_type" attribute of the created
76              PAM image.  It can be any string up to 255 characters.   If  you
77              don't  specify  this,  pamgauss generates a PAM with unspecified
78              tuple type.
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SEE ALSO

84       pnmconvol(1), pamtopnm(1), pgmkernel(1), pamseq(1), pam(1)
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HISTORY

88       pamgauss was new in Netpbm 10.23 (July 2004).
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92netpbm documentation              8 May 2004           Pamgauss User Manual(0)