title: OpenCV - Balance brightness of two images (C++)
body: <p>I'm new in OpenCV and also in Image processing.</p>
  
  <p>I have two images in grayscale. I want to balance their brightness (both images should have very similar brightness).</p>
  
  <p>I think about <code>equalizeHist</code>, but the result doesn't depend on the second image. I also find information about histogram matching, but I don't find any working example in OpenCV.</p>
  
  <p>Could you give me a hint and example how to do that?</p>