title: Faster way to Extract HOG of image's sliding window in Matlab
body: <p>I want to extract the HOG of every sliding window of size [wH,wW] of an image I.</p>
  
  <p>Currently what I have is:</p>
  
  <hr>
  
  <pre><code>windows = im2col(I, [wH,wW]);
  
  for i=1:step:size(windows,2)
  
      sub = reshape(windows(:,i), [wH,wW]);
  
      features(i,:) = featuresExtraction(sub);
  
  end
  </code></pre>
  
  <hr>
  
  <p>in which the featuresExtraction script will extract the HOG, etc.</p>
  
  <p>I try to run and see that it runs very very slowly. Do you have any suggestion to make it better?</p>