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    <title>MATLAB Central Newsreader - HowTo deal with this transposition in inverse problem ie. image restoration</title>
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      <pubDate>Fri, 03 Apr 2009 07:22:02 -0400</pubDate>
      <title>HowTo deal with this transposition in inverse problem ie. image restoration</title>
      <link>http://www.mathworks.com/matlabcentral/newsreader/view_thread/248218#639934</link>
      <author>timedcy Asayaku</author>
      <description>How to deal with this transposition in inverse problem ie. image restoration&lt;br&gt;
&lt;br&gt;
For example, when minimizing || g &amp;#8211; Hf ||^2 + &amp;#955;||Qf||^2 , where image matrix f &amp; g are the true and observed value in column-lexically heaped vectors, H is block-toeplitz matrix of the convolution kernel.&lt;br&gt;
&lt;br&gt;
Then the solution is f = H^Tg/(H^TH+ &amp;#955;Q^TQ) , here H^T means the conjugate transpose matrix of H.&lt;br&gt;
&lt;br&gt;
In programming, we usually compute it in the Fourier domain.&lt;br&gt;
My question is how to deal with H^T in convolution ie H &amp; x. conv2(H,x) (here H, x is a image matrix)?&lt;br&gt;
&lt;br&gt;
And what is the relation between (H^T x) and (H x)  in frequency domain? &lt;br&gt;
&lt;br&gt;
ifftn( conj(fftn(H)) .* fftn(x) )?&lt;br&gt;
or conv2(rot90(H,2), x)&lt;br&gt;
&lt;br&gt;
this problem confused me very long long time!&lt;br&gt;
&lt;br&gt;
Can you help me ?&lt;br&gt;
&lt;br&gt;
Sincerely timedcy&lt;br&gt;
20090403</description>
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