How to add light color to original image

edit

Do you want color all the image, or know beforehand which roi to color? Then addWeighted may be the direct solution

may be you can use HSV space :

int main (int argc,char **argv)
{
Mat img = imread("14405753399632309.png", IMREAD_ANYCOLOR);
Mat imgHSV,imgRGB;
cout << img.channels() << "\n";
cvtColor(img,imgHSV,COLOR_BGR2HSV);
for (int i = 0; i < imgHSV.rows; i++)
{
    Vec3b *ptr=(Vec3b*)imgHSV.ptr(i);
    for (int j=0;j<imgHSV.cols;j++,ptr++)
        if ((*ptr)[1]<127 )
            (*ptr)[1] *= 2;
        else
            (*ptr)[1] = 255;

}
cvtColor(imgHSV,imgRGB,COLOR_HSV2BGR);
imshow("Original ",img);
imshow("Saturate ",imgRGB);
waitKey();
return 0;
}

@LorenaGdL I had read the addweighted but why I need to source of array? Is it going to have more processing power?

@LBerger why if if ((ptr)[1]<127 ) (ptr)[1] = 2; else (ptr)[1] = 255; is needed? we need to compare what actually in the image?

TQ

@zms

      if ((ptr)[1]<127 ) // if value is less than 127
          (ptr)[1] *= 2;  // we can multiply by 2 (value would be less than 255
       else 
           (ptr)[1] = 255;// we saturate (saturate_cast is possible too  i think)

@zms: sorry, I haven't understood your last question. What is your problem with addWeighted?