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| author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
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| committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
| commit | 1017cbebe5d5edd859e0fddad0a8600f509f4821 (patch) | |
| tree | 78bdf336648566f7a7d55f42837357dea3dd674c /pamgauss.html | |
| parent | 16f2ac126651015a376eba864a3a35f738b0b25a (diff) | |
| download | netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.gz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.xz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.zip | |
Place user guide into Subversion repository
git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@181 9d0c8265-081b-0410-96cb-a4ca84ce46f8
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diff --git a/pamgauss.html b/pamgauss.html new file mode 100644 index 00000000..cef20227 --- /dev/null +++ b/pamgauss.html @@ -0,0 +1,128 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML><HEAD><TITLE>Pamgauss User Manual</TITLE></HEAD> +<BODY> +<H1>pamgauss</H1> +Updated: 8 May 2004 +<BR> +<A HREF="#index">Table Of Contents</A> + +<A NAME="name"> </A> +<H2>NAME</H2> + +pamgauss - create a two dimensional gaussian function as a PAM image + +<A NAME="synopsis"> </A> +<H2>SYNOPSIS</H2> + +<B>pamgauss</B> +<i>width</i> +<i>height</i> +<b>-sigma=</b><i>number</i> +[<b>-maxval=</b><i>number</i>] +[<b>-tupletype=</b><i>string</i>] + + +<p>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. + + + +<A NAME="examples"> </A> +<H2>EXAMPLES</H2> + +<pre> + pamgauss 3 3 -sigma=.5 -tupletype=GRAYSCALE | pamtopnm >gauss.pgm + pnmconvol -nooffset gauss.pgm myimage.ppm >blurred.ppm +</pre> + +<A NAME="description"> </A> +<H2>DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<p><b>pamgauss</b> 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. + +<p>The values are scaled so that the area under the surface of the +two-dimensional Gaussian function is the maxval of the image. + +<p>You can use this image, converted to PGM, as a convolution kernel +with <b>pnmconvol</b> to blur an image. (This technique is known as +Gaussian blurring). + +<i>width</i> and <i>height</i> are the dimensions of the image that +<b>pamgauss</b> generates. Mathematically speaking, they are the domain +of the two dimensional gaussian function. + +<p>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. + +<p>The output image is PAM. To turn it into a PGM that you can use +with <b>pnmconvol</b>, specify <b>-tupletype=GRAYSCALE</b> and pass +the output through <b>pamtopnm</b>. You must use the <b>-nooffset</b> +option on <b>pnmconvol</b> because zero means zero in the PAM that +<b>pamgauss</b> generates. + +<A NAME="options"> </A> +<H2>DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<dl> +<dt><b>-sigma=</b><i>number</i> + +<dd>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. Normally, +you want to make this number low enough that the function reaches zero +value before the edge of your image. + +<p><i>number</i> is in units of pixels. + +<p>This option is required. There is no default. + +<dt><b>-maxval=</b><i>number</i> +<dd>This is the maxval for the output image. It defaults to 255. + +<dt><b>-tupletype=</b><i>string</i> +<dd> +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, +<b>pamgauss</b> generates a PAM with unspecified tuple type. + +</dl> + +<A NAME="seealso"> </A> +<H2>SEE ALSO</H2> + +<B><A HREF="pnmconvol.html">pnmconvol</A></B>, +<B><A HREF="pamtopnm.html">pamtopnm</A></B>, +<B><A HREF="pgmkernel.html">pgmkernel</A></B>, +<B><A HREF="pamseq.html">pamseq</A></B>, +<B><A HREF="pam.html">pam</A></B> + +<A NAME="history"> </A> +<H2>HISTORY</H2> + +<p><b>pamgauss</b> was new in Netpbm 10.23 (July 2004). + +<HR> +<A NAME="index"> </A> +<H2>Table Of Contents</H2> +<UL> +<LI><A HREF="#name">NAME</A> +<LI><A HREF="#synopsis">SYNOPSIS</A> +<LI><A HREF="#examples">SYNOPSIS</A> +<LI><A HREF="#description">DESCRIPTION</A> +<LI><A HREF="#seealso">SEE ALSO</A> +<LI><A HREF="#history">AUTHORS</A> +</UL> +</BODY> +</HTML> |