title: Illumination invariant image
body: <p>I try to create an illumination invariant image with openCV like in this paper here: <a href="http://www.cvc.uab.es/adas/publications/alvarez_2008.pdf" rel="noreferrer">http://www.cvc.uab.es/adas/publications/alvarez_2008.pdf</a></p>
  
  <p>Has someone an idea how one can create that image from the log-log plot image in OpenCV?</p>