title: Why do I get a bad accuracy when using color histograms for training an SVM?
body: <p>I want to extract color histograms from the GTSRB dataset to train with them an SVM. 
  Unfortunately, I get an accuracy of only 0.18.
  I'm using OpenCV version 3.4.2.</p>
  
  <pre><code>def make_color_histo(X):
      histo_list = []
      for i in range(0, len(X)):
          hsv =cv2.cvtColor(X[i], cv2.COLOR_BGR2HSV)
          hist = cv2.calcHist([hsv], [0,1,2], None, (8,8,8), [0,180,0,256,0,256])
          hist = cv2.normalize(hist, hist)
          hist = hist.flatten()
          histo_list.append(hist)
      return histo_list
  </code></pre>
  
  <p>Am I doing something wrong in determining the color histograms?</p>