title: error while visualizing the cascade stage features
body: <p>I have trained a boosted cascade classifier with opencv and i want to visualize the cascade stages features as shown in the tutorial here: <a href="https://docs.opencv.org/3.3.0/dc/d88/" rel="nofollow noreferrer">https://docs.opencv.org/3.3.0/dc/d88/</a>...</p>
  
  <p>The problem is that everytime i run the batch: 
  <strong>opencv_visualisation --model=sunmodel.xml --image=sunn.bmp</strong></p>
  
  <p>where sunn.bmp is actually a positive sample from the training set, and i have also resized it to <strong>24*24</strong> as the defined dimension in the training process.</p>
  
  <p><strong>I get the following error:</strong> 
  <em>the model is not an haar or lbp feature based model! please select a model that can be visualised by the software</em></p>
  
  <p>Although i am using Haar features in the training, I am also using the cascade parameter mode to be: 
  <strong>-mode ALL</strong></p>
  
  <p>Any idea what is happening?</p>
  
  <p>Many thanks in advance</p>