learnopencv/Photoshop-Filters-in-OpenCV/brightness.cpp

#include <iostream>
#include <string>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>

using namespace std;
using namespace cv;


void nothing(int x, void* data) {}

void brightness(Mat img) {
	

	namedWindow("image");
	int slider = 100;
	createTrackbar("val","image",&slider,150,nothing);
	Mat hsv;

	while (true) {
		cvtColor(img, hsv, COLOR_BGR2HSV);
		float val = getTrackbarPos("val","image");
		val=val/100.0;
		Mat channels[3];
		split(hsv,channels);
		Mat H = channels[0];
		H.convertTo(H,CV_32F);
		Mat S = channels[1];
		S.convertTo(S,CV_32F);
		Mat V = channels[2];
		V.convertTo(V,CV_32F);

		for (int i=0; i < H.size().height; i++){
			for (int j=0; j < H.size().width; j++){
	// scale pixel values up or down for channel 1(Saturation)
				S.at<float>(i,j) *= val;
				if (S.at<float>(i,j) > 255)
					S.at<float>(i,j) = 255;

	// scale pixel values up or down for channel 2(Value)
				V.at<float>(i,j) *= val;
				if (V.at<float>(i,j) > 255)
					V.at<float>(i,j) = 255;
			}
		}
		H.convertTo(H,CV_8U);
		S.convertTo(S,CV_8U);
		V.convertTo(V,CV_8U);

		vector<Mat> hsvChannels{H,S,V};
		Mat hsvNew;
    		merge(hsvChannels,hsvNew);

    		Mat res;
    		cvtColor(hsvNew,res,COLOR_HSV2BGR);

    		imshow("original",img);
    		imshow("image",res);

	    	if (waitKey(1) == 'q')
	    		break;
		}
	destroyAllWindows();
}

int main(){
	Mat img = imread("image.jpg");
	brightness(img);
	return 0;
}