title: CImg cubic subpixel location
body: <p>I am trying to understand what a code is doing that uses CImg.h file of <a href="http://cimg.sourceforge.net/" rel="nofollow">C++ Image Processing Toolkit</a> for extract a value from an image.</p>
  
  <p>The function uses the following statement:</p>
  
  <pre><code>float dx(float x, float y, CImg&lt;float&gt; &amp;i) {
      float val = i.cubic_atXY(x + 0.5, y);
      return val;
  }
  </code></pre>
  
  <p>I think that it is trying to find the cubic interpolated subpixel on coordinate (x+0.5,y). I found that this functions are defined near line 12450 on the <a href="http://sourceforge.net/p/cimg/source/ci/master/tree/CImg.h" rel="nofollow">CImg.h</a> file, but I really do not not how to translate it to other code such as python.</p>
  
  <p>Someone that uses this kind of libraries is able to understand it?</p>