title: cv2.resize with Python : what exactly does the interpolation methods?
body: <p>Given a 9x9 matrix representing an image (its entries are a [R, G, B]), I want to create a new resized image with size 3x3 which each entry is computed as follows : </p>
  
  <ol>
  <li><p>divide the 9x9 matrix into 9 blocks of 3x3 matrices</p></li>
  <li><p>compute the mean (component-wise) of each 3x3 matrix bloc</p></li>
  <li><p>create the 3x3 image with these means.</p></li>
  </ol>
  
  <p>So far I have used the cv2 library with Python 3.6</p>
  
  <pre><code>image_blurred = cv2.resize(original_image, (3,3), interpolation=cv2.INTER_AREA)
  </code></pre>
  
  <p>But I am not sure about what precisely <code>cv2.INTER_AREA</code> does.</p>
  
  <p>Could you give me some information about this ? (There are some information <a href="https://docs.opencv.org/2.4/modules/imgproc/doc/geometric_transformations.html#void%20resize(InputArray%20src,%20OutputArray%20dst,%20Size%20dsize,%20double%20fx,%20double%20fy,%20int%20interpolation)" rel="nofollow noreferrer">here</a> but they do not give so many details.)</p>
  
  <p>Many thanks.</p>