title: Making darker area part of image brighter in openCV
body: <p>I am currently working on a road sign detection application on Android, using OpenCV, and found out that while processing frames in real-time, my camera often get focus on brighter parts of image, such as sky, and everything below (road, trees, and signs) is getting dark. Because of it my application is not able to detect these signs because they are too dark in this particular condition.
  Have anyone of you had to do with such problem and found decent solution? If so I would appreciate any clues to do this (especially with good performance which is important in real-time processing). </p>