title: ANTIALIAS vs BICUBIC in PIL(Python Image Library)?
body: <p>I am using PIL to resize my images, my case is to scale up the original image.</p>
  
  <p>I am confused about the algorithm used with `resample=ANTIALIAS'.</p>
  
  <p>According to the document below, <code>ANTIALIAS</code> seems to be the best while scaling down. I wonder In which case can <code>BICUBIC</code> win?(some of my test case shows bicubic is better choice)</p>
  
  <pre><code>An optional resampling filter. 
    This can be one of NEAREST (use nearest neighbour), 
    BILINEAR (linear interpolation in a 2x2 environment), 
    BICUBIC (cubic spline interpolation in a 4x4 environment), 
    or ANTIALIAS (a high-quality downsampling filter). 
  If omitted, or if the image has mode “1” or “P”, it is set NEAREST.
  </code></pre>
  
  <p>I am also confused about the <code>linear interpolation in a 2x2 environment</code> and <code>cubic spline interpolation in a 4x4 environment</code> in the document. What does it mean here?</p>
  
  <p>Thanks.</p>