title: Formula for Gaussian High-pass Filter
body: <p>As far as I know, the formula to generate the Gaussian low-pass filter is:</p>
  
  <pre><code>[x y] = meshgrid(round(-N/2):round(N/2), round(-N/2):round(N/2));
  GaussianFilter = exp((-x.^2/(2*sigma^2)-y.^2/(2*sigma^2)));
  </code></pre>
  
  <p>What should the formula for the high-pass filter be in this case?</p>