Final version

ppg.cpp

@@ -2,22 +2,38 @@
 #include "opencv2/videoio.hpp"
 #include "opencv2/highgui.hpp"
 
-#include <iostream>
-
-const int FPS = 30;
+const int FPS = 15;
 bool isDiscardData = true;
 int countDiscard = 0;
 const int DISCARD_DURATION = 5;
+const int BUFFER_DURATION = 30        ;
+const int I = 1;
+
+bool isBufferFull = false;
+int sampleIdBuffer = 0;
+
+std::vector<double> greenFFTModule;
+
+template <typename T>
+cv::Mat plotGraph(std::vector<T>& vals, int YRange[2])
+{
+	auto it = minmax_element(vals.begin(), vals.end());
+	float scale = 1./ceil(*it.second - *it.first);
+	float bias = *it.first;
+	int rows = YRange[1] - YRange[0] + 1;
+	cv::Mat image = 255*cv::Mat::ones( rows, vals.size(), CV_8UC3 );
+	image.setTo(255);
+	for (int i = 0; i < (int)vals.size()-1; i++)
+	{
+		cv::line(image, cv::Point(i, rows - 1 - (vals[i] - bias)*scale*YRange[1]), cv::Point(i+1, rows - 1 - (vals[i+1] - bias)*scale*YRange[1]), cv::Scalar(255, 0, 0), 1);
+	}
+	return image;
+}
 
 int main() 
 { 
   cv::VideoCapture cap;
   cap.open(0);
-  if (!cap.isOpened())
-  {
-    std::cerr << "[ERROR] Unable to open camera!" << std::endl;
-    return -2;
-  }
   //If Haard Cascade not found: error
   cv::CascadeClassifier faceDetector;
 	if( !faceDetector.load("./haarcascade_frontalface_alt.xml"))
@@ -25,6 +41,12 @@ int main()
 	std::cerr << "[ERROR] Unable to load face cascade" << std::endl;
 	return -1;
 	};
+  cv::Rect foreheadROI;
+  if (!cap.isOpened())
+  {
+    std::cerr << "[ERROR] Unable to open camera!" << std::endl;
+    return -2;
+  }
   
   while (true)
 	{
@@ -49,18 +71,69 @@ int main()
 						
 			//Draw Rectangle around the face
 			std::vector<cv::Rect> faceRectangles;
-			faceDetector.detectMultiScale(frame, faceRectangles, 1.1, 3, 0,
-			cv::Size(20, 20));
-			cv::rectangle(frame, faceRectangles[0], cv::Scalar(0, 0, 255), 1, 1, 0);
-			//Reduce to ROI
-			cv::Rect foreheadROI;
+			faceDetector.detectMultiScale(frame, faceRectangles, 1.1, 3, 0,cv::Size(20, 20));
+			
+			if (faceRectangles.size() > 0)
+			{
 				foreheadROI = faceRectangles[0];
-			foreheadROI.height *= 0.5;
+				foreheadROI.height *= 0.3;
+				
+				cv::rectangle(frame, faceRectangles[0], cv::Scalar(0, 0, 255), 1, 1, 0);
+				cv::rectangle(frame, foreheadROI, cv::Scalar(255, 0, 0), 1, 1, 0);
+				
+				cv::Mat frame_forehead = frame(foreheadROI);
+				cv::Scalar avg_forehead = mean(frame_forehead);
+				
+				//
+				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;
+					}
+				}
+				else
+				{
+					std::vector<double> greenSignalNormalized;
+					cv::Scalar mean, stddev;
+					cv::meanStdDev(greenSignal, mean, stddev);
+					for (int l_sample=0; l_sample < FPS*BUFFER_DURATION; l_sample++)
+					{
+						greenSignalNormalized.push_back((greenSignal.at<double>(0, l_sample) - mean[0])/stddev[0]);
+					}
+					
+					
+					int range[2] = {0, (int)(FPS*BUFFER_DURATION)};
+					
+					cv::Mat greenFFT;
+					///
+					cv::dft(greenSignalNormalized,greenFFT,cv::DFT_ROWS|cv::DFT_COMPLEX_OUTPUT);
+					cv::Mat planes[] = {cv::Mat::zeros(greenSignalNormalized.size(),1, CV_64F),
+					cv::Mat::zeros(greenSignalNormalized.size(),1, CV_64F)};
+					cv::split(greenFFT, planes); //planes[0] = Re(DFT(I),
+					//planes[1] = Im(DFT(I))
+					greenFFTModule.clear();
+					for (int l=0; l < planes[1].cols; l++)
+					{
+						double moduleFFT = pow(planes[1].at<double>(0,l),2) + pow(planes[0].at<double>(0,l),2);
+						greenFFTModule.push_back(sqrt(moduleFFT));
+					}
+					// display green FFT
+					cv::imshow("FFT module green", plotGraph(greenFFTModule, range));
+					
+				}
+				
+			}
 			
 			cv::imshow("Your Face PLS", frame);
 			if (cv::waitKey(1000.0/FPS) >= 0)
 			break;
+			
 		}
+		
 	}
 	return 0;
 }