Estimate Brightness of an image Opencv

Question

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

Answer 1

I suppose, that HSV color model will be usefull in your problem, where channel V is Value:

"Value is the brightness of the color and varies with color saturation. It ranges from 0 to 100%. When the value is ’0′ the color space will be totally black. With the increase in the value, the color space brightness up and shows various colors."

So use OpenCV method cvCvtColor(const CvArr* src, CvArr* dst, int code), that converts an image from one color space to another. In your case code = CV_BGR2HSV.Than calculate histogram of third channel V.