scilab/modules/signal_processing/help/en_US/correlation_convolution/convol2d.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!--
   3  * Add some comments about XML file
   4 -->
   5 <refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org" xml:lang="en_US" xml:id="convol2d">
   6     <refnamediv>
   7         <refname>convol2d</refname>
   8         <refpurpose>discrete 2-D convolution, using fft. </refpurpose>
   9     </refnamediv>
  10     <refsynopsisdiv>
  11         <title>Syntax</title>
  12         <synopsis>C = convol2d(A,B)</synopsis>
  13     </refsynopsisdiv>
  14     <refsection>
  15         <title>Parameters</title>
  16         <variablelist>
  17             <varlistentry>
  18                 <term>A</term>
  19                 <listitem>
  20                     <para>
  21                         a real or complex 2-D array.
  22                     </para>
  23                 </listitem>
  24             </varlistentry>
  25             <varlistentry>
  26                 <term>B</term>
  27                 <listitem>
  28                     <para>
  29                         a real or complex 2-D array.
  30                     </para>
  31                 </listitem>
  32             </varlistentry>
  33             <varlistentry>
  34                 <term>C</term>
  35                 <listitem>
  36                     <para>
  37                         a real or complex 2-D array.
  38                     </para>
  39                 </listitem>
  40             </varlistentry>
  41         </variablelist>
  42     </refsection>
  43     <refsection>
  44         <title>Description</title>
  45         <para>
  46             <literal>convol2d</literal> uses fft to compute the full
  47             two-dimensional discrete convolution. The
  48             dimensions of the result<literal>C</literal> are given by
  49             <literal>size(A)+size(B)+1</literal>. The indices of the
  50             center element of <literal>B</literal> are defined as
  51             <literal>floor((size(B)+1)/2)</literal>.
  52         </para>
  53     </refsection>
  54     <refsection>
  55         <title>Examples</title>
  56         <programlisting role="example"><![CDATA[
  57     s = [1 2 1; 0 0 0; -1 -2 -1];//Sobel horizontal edge kernel
  58     A = zeros(10,10);A(3:7,3:7) = 1;
  59     convol2d(s,A);
  60     ]]></programlisting>
  61     </refsection>
  62     <refsection>
  63         <title>See Also</title>
  64         <simplelist type="inline">
  65             <member>
  66                 <link linkend="conv2">conv2</link>
  67             </member>
  68             <member>
  69                 <link linkend="convol">convol</link>
  70             </member>
  71         </simplelist>
  72     </refsection>
  73     <refsection>
  74         <title>Used Functions</title>
  75         <para>
  76             The  <literal>convol2d</literal> function is based on the <link linkend="fft">fft</link> builtin.
  77         </para>
  78     </refsection>
  79     <refsection>
  80         <title>History</title>
  81         <revhistory>
  82             <revision>
  83                 <revnumber>5.4.0</revnumber>
  84                 <revremark>Function convol2d introduced.</revremark>
  85             </revision>
  86         </revhistory>
  87     </refsection>
  88 </refentry>