added green channel mean code

ppg.cpp

@@ -11,6 +11,9 @@ int DISCARD_DURATION=5;
 bool isDiscardData=true;
 int countDiscard=0;
 
+bool isBufferFull = false; //buffer variables to initialise before main();
+int sampleIdBuffer = 0;
+int BUFFER_DURATION= 5;
 
 int main(){ 
 	//Print "PPG algorithm" to terminal
@@ -71,6 +74,21 @@ int main(){
 			cv::Rect foreheadROI; //create a forehead ROI equal to the face ROI slightly moved upward.
 			foreheadROI = faceRectangles[0];
 			foreheadROI.height *= 0.3;
+
+			cv::Mat frame_forehead = frame(foreheadROI);
+			cv::Scalar avg_forehead = mean(frame_forehead); //calculates mean of object frame_forehead
+
+			//Buffer of average value for the green channel over the forehead ROI
+			cv::Mat greenSignal(1, FPS*BUFFER_DURATION, CV_64F); 
+			if (!isBufferFull)
+			{
+			greenSignal.at<double>(0, sampleIdBuffer) = avg_forehead[1] ;
+			sampleIdBuffer++;
+			if (sampleIdBuffer == FPS*BUFFER_DURATION)
+				{
+				isBufferFull = true;
+				}
+			}
 		}
 	}	
 }