title: HOG descriptor for pedestrian detection training
body: <p>I wonder why my HOG descriptor can't prevail the right silhouettes of the human body. I use the parameters like </p>
  
  <pre><code>CV_WRAP HOGDescriptor() : winSize(64,128), blockSize(16,16), blockStride(8,8),
          cellSize(8,8), nbins(9), derivAperture(1), winSigma(-1),
          histogramNormType(HOGDescriptor::L2Hys), L2HysThreshold(0.2), gammaCorrection(true),
          free_coef(-1.f), nlevels(HOGDescriptor::DEFAULT_NLEVELS), signedGradient(false)
      {}
  </code></pre>
  
  <p>When I plot them why I don't have correct silhouettes as the one sample shown in this <a href="http://lear.inrialpes.fr/pubs/2005/DT05/cvpr2005_talk.pdf" rel="nofollow noreferrer">discussion</a>.
  The two images are attached. Color image is my hog descriptor and gray is the one from the above link.</p>
  
  <p>What are the facts I need to look at to have correct silhouettes as shown in the image in the above discussion?</p>
  
  <p><a href="https://i.stack.imgur.com/SMFCJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SMFCJ.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/rUZUT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rUZUT.png" alt="enter image description here"></a></p>