title: Provide Integral Image to CascadeClassifier::detectMultiScale
body: <p>According to the <a href="http://docs.opencv.org/modules/objdetect/doc/cascade_classification.html#cascadeclassifier-setimage%20documentation" rel="nofollow">documentation of OpenCV Cascade Classifier</a> <code>CascadeClassifier::detectMultiScale()</code> computes the integral image of the provided image, which makes sense.</p>
  
  <p>Now wouldn't it be a nice thing to compute the integral image once for the image and <strong>provide this integral image to multiple different cascade classifiers</strong>?</p>
  
  <p>Documentation says further:</p>
  
  <blockquote>
    <p>Note</p>
    
    <p>in the old API you need to supply integral images (that can be obtained using Integral()) instead of the original image.</p>
  </blockquote>
  
  <p><strong>My question:</strong> Is there a hidden (or undocumented) way to still provide integral images to the classifier instead of grayscale images?</p>