title: What is the starting size of the detection window?
body: <p>When using <code>cv2.HOGDescriptor().detectMultiScale</code>, what is the starting size of the detection window used? Is it the same size as my training data?
  For example, if my training data are all 64*128 images then the detection window starts at 64*128?</p>
  <p>and how is the scaling factor used? For example, If I want to detect humans on an image of size 640*512, and I set <code>scale=1.05</code>, how is this 1.05 used?</p>