title: Matlab wiener filter for deblur
body: <p>I am using Wiener filter for deblurring an image. </p>
  
  <p><a href="http://www.mathworks.it/it/help/images/ref/deconvwnr.html" rel="nofollow">http://www.mathworks.it/it/help/images/ref/deconvwnr.html</a></p>
  
  <p>The important snippet is here:</p>
  
  <pre><code>estimated_nsr = noise_var / var(I(:));
  wnr3 = deconvwnr(blurred_noisy, PSF, estimated_nsr);
  </code></pre>
  
  <p>The problem is that deconwnr needs an estitmate of NSR calculated with the original image I.<br>
  <strong>But</strong> I don't have the original image, I have only the <code>blurred_noisy</code> image.</p>
  
  <p>What value should I pass as estmated_nsr?</p>