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

A bit of OpenCV C++ source code for a trivial check to differentiate between light and dark images. This is inspired by the answer above provided years ago by @ann-orlova:

const int darkness_threshold = 128; // you need to determine what threshold to use

cv::Mat mat = get_image_from_device();

cv::Mat hsv;
cv::cvtColor(mat, hsv, CV_BGR2HSV);
const auto result = cv::mean(hsv);

// cv::mean() will return 3 numbers, one for each channel:
//      0=hue
//      1=saturation
//      2=value (brightness)

if (result[2] < darkness_threshold)
{
    process_dark_image(mat);
}
else
{
    process_light_image(mat);
}