Brightness is not adjusting in the image

Question

I am trying to achieve this result

but what I am trying is

Mat out = imread ("F:\\image.jpg");
Mat img2 = Mat(out.size(),out.type());
cv_Gamma(out,image ,0.7);
blending_overlay(image , out , image);

and this give me the following result

and the original image is

It looks that there is a lack of brightness in my image but when I increase the brightness it still not give the required result

Edit Blending Overlay

void blending_overlay(Mat& img1 , Mat& img2 , Mat& out)
{

Mat result(img1.size(), CV_32FC3);
for(int i = 0; i < img1.size().height; ++i){
    for(int j = 0; j < img1.size().width; ++j){

        for (int c=0 ; c<img1.channels();c++){
            float target = (float)img1.at<uchar>(i, 3*j+c)/255.0 ;
            float blend =  (float)img2.at<uchar>(i, 3*j+c)/255.0 ;
            if(target > 0.5){
                result.at<float>(i, 3*j+c) = ((1 - (1-2*(target-0.5)) * (1-blend)));

                }
            else{
                result.at<float>(i, 3*j+c) = ((2*target) * blend);
                }
        }
    }
}
result.convertTo(out,CV_8UC3,255);
}

In fact I have tried every blending mode, what I understand about this is that I may multiply with a linear gradient which come from yellow to white, but how to make that gradient is not understandable for me. Any algorithm regarding this scenario would also be appreciated.

Answer 1

It seems that you need gamma correction.

Take a look here:

http://subokita.com/2013/06/18/simple-and-fast-gamma-correction-on-opencv/

and the source of link above (with source/result pictures):

http://imagingsolution.net/program/opencv/gamma-correction/