title: Estimate Brightness of an image Opencv
body: <p>I have been trying to obtain the image brightness in Opencv, and so far I have used calcHist and considered the average of the histogram values. However, I feel this is not accurate, as it does not actually determine the brightness of an image. I performed calcHist over a gray scale version of the image, and tried to differentiate between the avergae values obtained from bright images over that of moderate ones. I have not been successful so far. Could you please help me with a method or algorithm, that can be realised through OpenCv, to estimate brightness of an image? Thanks in advance.</p>