title: What does clip limit mean exactly in OpenCV CLAHE?
body: <p>I have read a lot article saying that clip limit is the limit of the slope of CDF. But in OpenCV, that parameter can be set to 0~999..., I don't know the maximum of this parameter, isn't sum of the PDF equal to 1? How could the slope is greater than 1?
  Another way of saying clip limit is that is the limit to every graylevel's count, so for example, if I set tile to (8,8), there is no way that any graylevel in that tile have over 64 pixel, but if I set limit over 64, the results are still changing.
  Please enlighten me with any point of view.</p>